Пакет: xz

XZDIFF(1)			   XZ Utils			     XZDIFF(1)



NAME
       xzcmp, xzdiff, lzcmp, lzdiff - compare compressed files

SYNOPSIS
       xzcmp [option...]  file1 [file2]
       xzdiff ...
       lzcmp ...
       lzdiff ...

DESCRIPTION
       xzcmp  and  xzdiff  compare uncompressed contents of two files.	Uncom‐
       pressed data and options are passed to cmp(1) or diff(1) unless	--help
       or --version is specified.

       If  both	 file1 and file2 are specified, they can be uncompressed files
       or files in formats that xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1)  can decompress.	The required decompression commands are deter‐
       mined from the filename suffixes of file1 and file2.  A	file  with  an
       unknown suffix is assumed to be either uncompressed or in a format that
       xz(1) can decompress.

       If only one filename is provided, file1 must have a suffix  of  a  sup‐
       ported compression format and the name for file2 is assumed to be file1
       with the compression format suffix removed.

       The commands lzcmp and lzdiff are provided for  backward	 compatibility
       with LZMA Utils.

EXIT STATUS
       If  a  decompression error occurs, the exit status is 2.	 Otherwise the
       exit status of cmp(1) or diff(1) is used.

SEE ALSO
       cmp(1), diff(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1)



Tukaani				  2024-02-13			     XZDIFF(1)

XZ(1)				   XZ Utils				 XZ(1)



NAME
       xz,  unxz,  xzcat, lzma, unlzma, lzcat - Compress or decompress .xz and
       .lzma files

SYNOPSIS
       xz [option...]  [file...]

COMMAND ALIASES
       unxz is equivalent to xz --decompress.
       xzcat is equivalent to xz --decompress --stdout.
       lzma is equivalent to xz --format=lzma.
       unlzma is equivalent to xz --format=lzma --decompress.
       lzcat is equivalent to xz --format=lzma --decompress --stdout.

       When writing scripts that need to decompress files, it  is  recommended
       to  always use the name xz with appropriate arguments (xz -d or xz -dc)
       instead of the names unxz and xzcat.

DESCRIPTION
       xz is a general-purpose data compression tool with command line	syntax
       similar	to  gzip(1)  and  bzip2(1).  The native file format is the .xz
       format, but the legacy .lzma format used by LZMA	 Utils	and  raw  com‐
       pressed	streams	 with  no container format headers are also supported.
       In addition, decompression of the .lz format used by lzip is supported.

       xz compresses or decompresses each file according to the selected oper‐
       ation mode.  If no files are given or file is -, xz reads from standard
       input and writes the processed data to standard output.	xz will refuse
       (display	 an error and skip the file) to write compressed data to stan‐
       dard output if it is a terminal.	 Similarly, xz	will  refuse  to  read
       compressed data from standard input if it is a terminal.

       Unless  --stdout	 is specified, files other than - are written to a new
       file whose name is derived from the source file name:

       •  When compressing, the suffix of  the	target	file  format  (.xz  or
	  .lzma)  is  appended	to the source filename to get the target file‐
	  name.

       •  When decompressing, the .xz, .lzma, or .lz suffix  is	 removed  from
	  the  filename	 to  get  the target filename.	xz also recognizes the
	  suffixes .txz and .tlz, and replaces them with the .tar suffix.

       If the target file already exists, an error is displayed and  the  file
       is skipped.

       Unless  writing	to standard output, xz will display a warning and skip
       the file if any of the following applies:

       •  File is not a regular file.  Symbolic links are  not	followed,  and
	  thus they are not considered to be regular files.

       •  File has more than one hard link.

       •  File has setuid, setgid, or sticky bit set.

       •  The  operation  mode	is  set to compress and the file already has a
	  suffix of the target file format (.xz or .txz	 when  compressing  to
	  the .xz format, and .lzma or .tlz when compressing to the .lzma for‐
	  mat).

       •  The operation mode is set to decompress and the file doesn't have  a
	  suffix of any of the supported file formats (.xz, .txz, .lzma, .tlz,
	  or .lz).

       After successfully compressing or decompressing the file, xz copies the
       owner,  group, permissions, access time, and modification time from the
       source file to the target file.	If copying the group fails,  the  per‐
       missions are modified so that the target file doesn't become accessible
       to users who didn't have permission to  access  the  source  file.   xz
       doesn't support copying other metadata like access control lists or ex‐
       tended attributes yet.

       Once the target file has been successfully closed, the source  file  is
       removed	unless --keep was specified.  The source file is never removed
       if the output is written to standard output or if an error occurs.

       Sending SIGINFO or SIGUSR1 to the xz process makes  it  print  progress
       information  to	standard  error.  This has only limited use since when
       standard error is a terminal, using --verbose will display an automati‐
       cally updating progress indicator.

   Memory usage
       The  memory  usage of xz varies from a few hundred kilobytes to several
       gigabytes depending on the compression  settings.   The	settings  used
       when compressing a file determine the memory requirements of the decom‐
       pressor.	 Typically the decompressor needs 5 % to 20 % of the amount of
       memory that the compressor needed when creating the file.  For example,
       decompressing a file created with xz -9 currently  requires  65 MiB  of
       memory.	 Still,	 it is possible to have .xz files that require several
       gigabytes of memory to decompress.

       Especially users of older systems may  find  the	 possibility  of  very
       large  memory  usage  annoying.	To prevent uncomfortable surprises, xz
       has a built-in memory usage limiter,  which  is	disabled  by  default.
       While  some operating systems provide ways to limit the memory usage of
       processes, relying on it wasn't deemed to be flexible enough (for exam‐
       ple, using ulimit(1) to limit virtual memory tends to cripple mmap(2)).

       The  memory  usage  limiter can be enabled with the command line option
       --memlimit=limit.  Often it is more convenient to enable the limiter by
       default	by  setting the environment variable XZ_DEFAULTS, for example,
       XZ_DEFAULTS=--memlimit=150MiB.  It is possible to set the limits	 sepa‐
       rately  for  compression	 and  decompression  by	 using --memlimit-com‐
       press=limit and --memlimit-decompress=limit.  Using these  two  options
       outside	XZ_DEFAULTS is rarely useful because a single run of xz cannot
       do both compression  and	 decompression	and  --memlimit=limit  (or  -M
       limit) is shorter to type on the command line.

       If  the specified memory usage limit is exceeded when decompressing, xz
       will display an error and decompressing the file	 will  fail.   If  the
       limit  is  exceeded when compressing, xz will try to scale the settings
       down so that the limit is no longer exceeded (except when using	--for‐
       mat=raw	or --no-adjust).  This way the operation won't fail unless the
       limit is very small.  The scaling of the settings is done in steps that
       don't match the compression level presets, for example, if the limit is
       only slightly less than the amount required for	xz  -9,	 the  settings
       will be scaled down only a little, not all the way down to xz -8.

   Concatenation and padding with .xz files
       It is possible to concatenate .xz files as is.  xz will decompress such
       files as if they were a single .xz file.

       It is possible to insert padding between the concatenated parts or  af‐
       ter the last part.  The padding must consist of null bytes and the size
       of the padding must be a multiple of four bytes.	 This can  be  useful,
       for  example,  if the .xz file is stored on a medium that measures file
       sizes in 512-byte blocks.

       Concatenation and padding are not  allowed  with	 .lzma	files  or  raw
       streams.

OPTIONS
   Integer suffixes and special values
       In  most places where an integer argument is expected, an optional suf‐
       fix is supported to easily indicate large integers.  There must	be  no
       space between the integer and the suffix.

       KiB    Multiply	the integer by 1,024 (2^10).  Ki, k, kB, K, and KB are
	      accepted as synonyms for KiB.

       MiB    Multiply the integer by 1,048,576 (2^20).	 Mi, m, M, and MB  are
	      accepted as synonyms for MiB.

       GiB    Multiply	the integer by 1,073,741,824 (2^30).  Gi, g, G, and GB
	      are accepted as synonyms for GiB.

       The special value max can be used to indicate the maximum integer value
       supported by the option.

   Operation mode
       If  multiple  operation	mode options are given, the last one takes ef‐
       fect.

       -z, --compress
	      Compress.	 This is the default operation mode when no  operation
	      mode  option is specified and no other operation mode is implied
	      from the command name (for example, unxz implies --decompress).

	      After successful compression, the source file is removed	unless
	      writing to standard output or --keep was specified.

       -d, --decompress, --uncompress
	      Decompress.   After successful decompression, the source file is
	      removed unless writing to standard output or --keep  was	speci‐
	      fied.

       -t, --test
	      Test  the integrity of compressed files.	This option is equiva‐
	      lent to --decompress --stdout except that the decompressed  data
	      is  discarded  instead  of being written to standard output.  No
	      files are created or removed.

       -l, --list
	      Print information about compressed files.	 No uncompressed  out‐
	      put  is  produced, and no files are created or removed.  In list
	      mode, the program cannot read the compressed data from  standard
	      input or from other unseekable sources.

	      The  default  listing  shows  basic information about files, one
	      file per line.  To get more detailed information, use  also  the
	      --verbose	 option.   For	even  more  information, use --verbose
	      twice, but note that this may be slow, because getting  all  the
	      extra  information  requires  many  seeks.  The width of verbose
	      output exceeds 80 characters, so piping the output to, for exam‐
	      ple,  less -S  may  be  convenient  if  the  terminal isn't wide
	      enough.

	      The exact output may vary between xz versions and different  lo‐
	      cales.   For  machine-readable  output, --robot --list should be
	      used.

   Operation modifiers
       -k, --keep
	      Don't delete the input files.

	      Since xz 5.2.6, this option also makes xz compress or decompress
	      even if the input is a symbolic link to a regular file, has more
	      than one hard link, or has the setuid,  setgid,  or  sticky  bit
	      set.   The setuid, setgid, and sticky bits are not copied to the
	      target file.  In	earlier	 versions  this	 was  only  done  with
	      --force.

       -f, --force
	      This option has several effects:

	      •	 If the target file already exists, delete it before compress‐
		 ing or decompressing.

	      •	 Compress or decompress even if the input is a	symbolic  link
		 to  a	regular	 file, has more than one hard link, or has the
		 setuid, setgid, or sticky bit set.  The setuid,  setgid,  and
		 sticky bits are not copied to the target file.

	      •	 When  used with --decompress --stdout and xz cannot recognize
		 the type of the source file, copy the source file  as	is  to
		 standard  output.   This allows xzcat --force to be used like
		 cat(1) for files that have not been compressed with xz.  Note
		 that in future, xz might support new compressed file formats,
		 which may make xz decompress more types of files  instead  of
		 copying  them	as is to standard output.  --format=format can
		 be used to restrict xz to decompress only a single file  for‐
		 mat.

       -c, --stdout, --to-stdout
	      Write the compressed or decompressed data to standard output in‐
	      stead of a file.	This implies --keep.

       --single-stream
	      Decompress only the first .xz stream, and silently ignore possi‐
	      ble  remaining  input  data following the stream.	 Normally such
	      trailing garbage makes xz display an error.

	      xz never decompresses more than one stream from .lzma  files  or
	      raw  streams, but this option still makes xz ignore the possible
	      trailing data after the .lzma file or raw stream.

	      This option has no effect if the operation mode is not  --decom‐
	      press or --test.

       --no-sparse
	      Disable  creation of sparse files.  By default, if decompressing
	      into a regular file, xz tries to make the file sparse if the de‐
	      compressed  data	contains  long	sequences of binary zeros.  It
	      also works when writing to standard output as long  as  standard
	      output  is  connected  to	 a regular file and certain additional
	      conditions are met to make it safe.  Creating sparse  files  may
	      save  disk  space and speed up the decompression by reducing the
	      amount of disk I/O.

       -S .suf, --suffix=.suf
	      When compressing, use .suf as the suffix for the target file in‐
	      stead  of	 .xz  or .lzma.	 If not writing to standard output and
	      the source file already has the suffix .suf, a warning  is  dis‐
	      played and the file is skipped.

	      When  decompressing, recognize files with the suffix .suf in ad‐
	      dition to files with the .xz, .txz, .lzma, .tlz, or .lz  suffix.
	      If the source file has the suffix .suf, the suffix is removed to
	      get the target filename.

	      When compressing or decompressing	 raw  streams  (--format=raw),
	      the  suffix  must always be specified unless writing to standard
	      output, because there is no default suffix for raw streams.

       --files[=file]
	      Read the filenames to process from file;	if  file  is  omitted,
	      filenames	 are read from standard input.	Filenames must be ter‐
	      minated with the newline character.  A dash (-) is  taken	 as  a
	      regular  filename; it doesn't mean standard input.  If filenames
	      are given also as command line arguments, they are processed be‐
	      fore the filenames read from file.

       --files0[=file]
	      This  is	identical  to --files[=file] except that each filename
	      must be terminated with the null character.

   Basic file format and compression options
       -F format, --format=format
	      Specify the file format to compress or decompress:

	      auto   This is the default.  When compressing, auto  is  equiva‐
		     lent  to xz.  When decompressing, the format of the input
		     file is automatically detected.  Note  that  raw  streams
		     (created with --format=raw) cannot be auto-detected.

	      xz     Compress to the .xz file format, or accept only .xz files
		     when decompressing.

	      lzma, alone
		     Compress to the legacy .lzma file format, or accept  only
		     .lzma  files  when	 decompressing.	  The alternative name
		     alone is provided for backwards compatibility  with  LZMA
		     Utils.

	      lzip   Accept only .lz files when decompressing.	Compression is
		     not supported.

		     The .lz format version 0 and the unextended version 1 are
		     supported.	 Version 0 files were produced by lzip 1.3 and
		     older.  Such files aren't common but may  be  found  from
		     file  archives  as a few source packages were released in
		     this format.  People might have  old  personal  files  in
		     this  format  too.	  Decompression support for the format
		     version 0 was removed in lzip 1.18.

		     lzip 1.4 and later create files in the format version  1.
		     The  sync	flush marker extension to the format version 1
		     was added in lzip 1.6.  This extension is rarely used and
		     isn't supported by xz (diagnosed as corrupt input).

	      raw    Compress  or  uncompress a raw stream (no headers).  This
		     is meant for advanced users only.	To decode raw streams,
		     you need use --format=raw and explicitly specify the fil‐
		     ter chain, which normally would have been stored  in  the
		     container headers.

       -C check, --check=check
	      Specify  the  type  of the integrity check.  The check is calcu‐
	      lated from the uncompressed data and stored  in  the  .xz	 file.
	      This  option  has	 an  effect only when compressing into the .xz
	      format; the .lzma format doesn't support integrity checks.   The
	      integrity check (if any) is verified when the .xz file is decom‐
	      pressed.

	      Supported check types:

	      none   Don't calculate an integrity check at all.	 This is  usu‐
		     ally  a  bad  idea.  This can be useful when integrity of
		     the data is verified by other means anyway.

	      crc32  Calculate CRC32  using  the  polynomial  from  IEEE-802.3
		     (Ethernet).

	      crc64  Calculate CRC64 using the polynomial from ECMA-182.  This
		     is the default, since it is slightly better than CRC32 at
		     detecting	damaged files and the speed difference is neg‐
		     ligible.

	      sha256 Calculate SHA-256.	 This is somewhat  slower  than	 CRC32
		     and CRC64.

	      Integrity	 of the .xz headers is always verified with CRC32.  It
	      is not possible to change or disable it.

       --ignore-check
	      Don't verify the integrity check of the compressed data when de‐
	      compressing.   The CRC32 values in the .xz headers will still be
	      verified normally.

	      Do not use this option unless you know what you are doing.  Pos‐
	      sible reasons to use this option:

	      •	 Trying to recover data from a corrupt .xz file.

	      •	 Speeding  up decompression.  This matters mostly with SHA-256
		 or with files that have compressed extremely well.  It's rec‐
		 ommended  to  not use this option for this purpose unless the
		 file integrity is verified externally in some other way.

       -0 ... -9
	      Select a compression preset level.  The default is -6.  If  mul‐
	      tiple  preset  levels  are specified, the last one takes effect.
	      If a custom filter chain was already specified, setting  a  com‐
	      pression preset level clears the custom filter chain.

	      The  differences	between	 the presets are more significant than
	      with gzip(1) and bzip2(1).  The  selected	 compression  settings
	      determine	 the memory requirements of the decompressor, thus us‐
	      ing a too high preset level might make it painful to  decompress
	      the  file	 on an old system with little RAM.  Specifically, it's
	      not a good idea to blindly use -9 for everything like  it	 often
	      is with gzip(1) and bzip2(1).

	      -0 ... -3
		     These  are somewhat fast presets.	-0 is sometimes faster
		     than gzip -9 while compressing much better.   The	higher
		     ones  often have speed comparable to bzip2(1) with compa‐
		     rable or better compression ratio, although  the  results
		     depend a lot on the type of data being compressed.

	      -4 ... -6
		     Good  to very good compression while keeping decompressor
		     memory usage reasonable even for old systems.  -6 is  the
		     default,  which is usually a good choice for distributing
		     files that need to be decompressible even on systems with
		     only  16 MiB  RAM.	  (-5e or -6e may be worth considering
		     too.  See --extreme.)

	      -7 ... -9
		     These are like -6 but with higher compressor  and	decom‐
		     pressor  memory requirements.  These are useful only when
		     compressing files bigger than 8 MiB, 16 MiB, and  32 MiB,
		     respectively.

	      On the same hardware, the decompression speed is approximately a
	      constant number of bytes of  compressed  data  per  second.   In
	      other  words,  the better the compression, the faster the decom‐
	      pression will usually be.	 This also means that  the  amount  of
	      uncompressed output produced per second can vary a lot.

	      The following table summarises the features of the presets:

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem -0;256 KiB;0;3 MiB;1 MiB -1;1 MiB;1;9
		     MiB;2 MiB -2;2 MiB;2;17 MiB;3 MiB -3;4 MiB;3;32 MiB;5 MiB
		     -4;4 MiB;4;48 MiB;5 MiB  -5;8  MiB;5;94  MiB;9  MiB  -6;8
		     MiB;6;94  MiB;9  MiB  -7;16  MiB;6;186  MiB;17  MiB -8;32
		     MiB;6;370 MiB;33 MiB -9;64 MiB;6;674 MiB;65 MiB

	      Column descriptions:

	      •	 DictSize is the LZMA2 dictionary size.	 It is waste of memory
		 to  use a dictionary bigger than the size of the uncompressed
		 file.	This is why it is good to avoid using the  presets  -7
		 ...  -9 when there's no real need for them.  At -6 and lower,
		 the amount of memory wasted is usually low enough to not mat‐
		 ter.

	      •	 CompCPU  is a simplified representation of the LZMA2 settings
		 that affect compression speed.	 The dictionary	 size  affects
		 speed too, so while CompCPU is the same for levels -6 ... -9,
		 higher levels still tend to be a little slower.  To get  even
		 slower and thus possibly better compression, see --extreme.

	      •	 CompMem  contains  the	 compressor memory requirements in the
		 single-threaded mode.	It may vary slightly between  xz  ver‐
		 sions.

	      •	 DecMem	 contains  the decompressor memory requirements.  That
		 is, the compression settings determine	 the  memory  require‐
		 ments of the decompressor.  The exact decompressor memory us‐
		 age is slightly more than the LZMA2 dictionary size, but  the
		 values	 in  the  table	 have been rounded up to the next full
		 MiB.

	      Memory requirements of the multi-threaded mode are significantly
	      higher  than that of the single-threaded mode.  With the default
	      value of --block-size, each thread needs 3*3*DictSize plus Comp‐
	      Mem  or  DecMem.	For example, four threads with preset -6 needs
	      660–670 MiB of memory.

       -e, --extreme
	      Use a slower variant of the selected  compression	 preset	 level
	      (-0 ... -9) to hopefully get a little bit better compression ra‐
	      tio, but with bad luck this can also make it worse.   Decompres‐
	      sor  memory  usage  is not affected, but compressor memory usage
	      increases a little at preset levels -0 ... -3.

	      Since there are two presets  with	 dictionary  sizes  4 MiB  and
	      8 MiB,  the  presets  -3e	 and  -5e use slightly faster settings
	      (lower CompCPU) than -4e and -6e, respectively.  That way no two
	      presets are identical.

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem  -0e;256  KiB;8;4  MiB;1  MiB	 -1e;1
		     MiB;8;13	MiB;2  MiB  -2e;2  MiB;8;25  MiB;3  MiB	 -3e;4
		     MiB;7;48  MiB;5  MiB  -4e;4  MiB;8;48  MiB;5  MiB	 -5e;8
		     MiB;7;94  MiB;9  MiB  -6e;8  MiB;8;94  MiB;9  MiB	-7e;16
		     MiB;8;186 MiB;17 MiB -8e;32 MiB;8;370 MiB;33  MiB	-9e;64
		     MiB;8;674 MiB;65 MiB

	      For  example,  there  are a total of four presets that use 8 MiB
	      dictionary, whose order from the fastest to the slowest  is  -5,
	      -6, -5e, and -6e.

       --fast
       --best These  are  somewhat  misleading	aliases for -0 and -9, respec‐
	      tively.  These are provided  only	 for  backwards	 compatibility
	      with LZMA Utils.	Avoid using these options.

       --block-size=size
	      When  compressing	 to  the .xz format, split the input data into
	      blocks of size bytes.  The blocks are  compressed	 independently
	      from each other, which helps with multi-threading and makes lim‐
	      ited random-access decompression possible.  This option is typi‐
	      cally  used to override the default block size in multi-threaded
	      mode, but this option can be used in single-threaded mode too.

	      In multi-threaded mode about three times size bytes will be  al‐
	      located  in each thread for buffering input and output.  The de‐
	      fault size is three times the LZMA2 dictionary size  or  1  MiB,
	      whichever is more.  Typically a good value is 2–4 times the size
	      of the LZMA2 dictionary or at least 1 MiB.  Using size less than
	      the LZMA2 dictionary size is waste of RAM because then the LZMA2
	      dictionary buffer will never get fully used.  In	multi-threaded
	      mode,  the  sizes of the blocks are stored in the block headers.
	      This size information is required for multi-threaded  decompres‐
	      sion.

	      In  single-threaded  mode no block splitting is done by default.
	      Setting this option doesn't affect memory usage.	No size infor‐
	      mation is stored in block headers, thus files created in single-
	      threaded mode won't be identical	to  files  created  in	multi-
	      threaded	mode.  The lack of size information also means that xz
	      won't be able decompress the files in multi-threaded mode.

       --block-list=items
	      When compressing to the .xz format, start a new  block  with  an
	      optional custom filter chain after the given intervals of uncom‐
	      pressed data.

	      The items are a comma-separated list.  Each item consists of  an
	      optional filter chain number between 0 and 9 followed by a colon
	      (:) and a required size of uncompressed data.  Omitting an  item
	      (two  or more consecutive commas) is a shorthand to use the size
	      and filters of the previous item.

	      If the input file is bigger than the sum of the sizes in	items,
	      the  last item is repeated until the end of the file.  A special
	      value of 0 may be used as the last size  to  indicate  that  the
	      rest of the file should be encoded as a single block.

	      An  alternative  filter chain for each block can be specified in
	      combination with the --filters1=filters  ...  --filters9=filters
	      options.	 These options define filter chains with an identifier
	      between 1–9.  Filter chain 0 can be used to refer to the default
	      filter  chain,  which  is	 the  same  as not specifying a filter
	      chain.  The filter chain identifier can be used before  the  un‐
	      compressed  size,	 followed by a colon (:).  For example, if one
	      specifies	 --block-list=1:2MiB,3:2MiB,2:4MiB,,2MiB,0:4MiB	  then
	      blocks will be created using:

	      •	 The filter chain specified by --filters1 and 2 MiB input

	      •	 The filter chain specified by --filters3 and 2 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The default filter chain and 2 MiB input

	      •	 The  default filter chain and 4 MiB input for every block un‐
		 til end of input.

	      If one specifies a size that exceeds the	encoder's  block  size
	      (either  the  default value in threaded mode or the value speci‐
	      fied with --block-size=size), the encoder will create additional
	      blocks while keeping the boundaries specified in items.  For ex‐
	      ample,	  if	  one	    specifies	    --block-size=10MiB
	      --block-list=5MiB,10MiB,8MiB,12MiB,24MiB	and  the input file is
	      80 MiB, one will get 11 blocks: 5, 10, 8, 10, 2, 10, 10, 4,  10,
	      10, and 1 MiB.

	      In multi-threaded mode the sizes of the blocks are stored in the
	      block headers.  This isn't done in single-threaded mode, so  the
	      encoded  output won't be identical to that of the multi-threaded
	      mode.

       --flush-timeout=timeout
	      When compressing, if more than timeout milliseconds (a  positive
	      integer)	has  passed  since the previous flush and reading more
	      input would block, all the pending input data  is	 flushed  from
	      the  encoder  and made available in the output stream.  This can
	      be useful if xz is used to compress data that is streamed over a
	      network.	 Small	timeout	 values make the data available at the
	      receiving end with a small delay, but large timeout values  give
	      better compression ratio.

	      This  feature  is disabled by default.  If this option is speci‐
	      fied more than once, the last one	 takes	effect.	  The  special
	      timeout  value  of 0 can be used to explicitly disable this fea‐
	      ture.

	      This feature is not available on non-POSIX systems.

	      This feature is still experimental.  Currently xz is  unsuitable
	      for  decompressing  the  stream  in real time due to how xz does
	      buffering.

       --memlimit-compress=limit
	      Set a memory usage limit for compression.	  If  this  option  is
	      specified multiple times, the last one takes effect.

	      If the compression settings exceed the limit, xz will attempt to
	      adjust the settings downwards so that the limit is no longer ex‐
	      ceeded  and display a notice that automatic adjustment was done.
	      The adjustments are done in this order: reducing the  number  of
	      threads, switching to single-threaded mode if even one thread in
	      multi-threaded mode exceeds the limit, and finally reducing  the
	      LZMA2 dictionary size.

	      When  compressing	 with  --format=raw or if --no-adjust has been
	      specified, only the number of threads may be  reduced  since  it
	      can be done without affecting the compressed output.

	      If  the  limit cannot be met even with the adjustments described
	      above, an error is displayed and xz will exit with  exit	status
	      1.

	      The limit can be specified in multiple ways:

	      •	 The  limit can be an absolute value in bytes.	Using an inte‐
		 ger suffix like MiB can be useful.  Example:  --memlimit-com‐
		 press=80MiB

	      •	 The  limit can be specified as a percentage of total physical
		 memory (RAM).	This can be useful especially when setting the
		 XZ_DEFAULTS  environment  variable  in a shell initialization
		 script that is shared between different computers.  That  way
		 the  limit  is automatically bigger on systems with more mem‐
		 ory.  Example: --memlimit-compress=70%

	      •	 The limit can be reset back to its default value  by  setting
		 it  to	 0.  This is currently equivalent to setting the limit
		 to max (no memory usage limit).

	      For 32-bit xz there is a special case: if	 the  limit  would  be
	      over 4020 MiB, the limit is set to 4020 MiB.  On MIPS32 2000 MiB
	      is used instead.	(The values 0 and max aren't affected by this.
	      A similar feature doesn't exist for decompression.)  This can be
	      helpful when a 32-bit executable has  access  to	4 GiB  address
	      space  (2	 GiB on MIPS32) while hopefully doing no harm in other
	      situations.

	      See also the section Memory usage.

       --memlimit-decompress=limit
	      Set a memory usage limit for decompression.  This	 also  affects
	      the  --list  mode.  If the operation is not possible without ex‐
	      ceeding the limit, xz will display an  error  and	 decompressing
	      the  file will fail.  See --memlimit-compress=limit for possible
	      ways to specify the limit.

       --memlimit-mt-decompress=limit
	      Set a memory usage limit for multi-threaded decompression.  This
	      can  only	 affect the number of threads; this will never make xz
	      refuse to decompress a file.  If limit is too low to  allow  any
	      multi-threading,	the  limit  is ignored and xz will continue in
	      single-threaded mode.  Note that if  also	 --memlimit-decompress
	      is used, it will always apply to both single-threaded and multi-
	      threaded modes, and so the effective limit  for  multi-threading
	      will  never  be higher than the limit set with --memlimit-decom‐
	      press.

	      In contrast to the other	memory	usage  limit  options,	--mem‐
	      limit-mt-decompress=limit	 has  a system-specific default limit.
	      xz --info-memory can be used to see the current value.

	      This option and its default  value  exist	 because  without  any
	      limit  the  threaded decompressor could end up allocating an in‐
	      sane amount of memory with some input  files.   If  the  default
	      limit is too low on your system, feel free to increase the limit
	      but never set it to a value larger than the amount of usable RAM
	      as  with	appropriate  input  files  xz will attempt to use that
	      amount of memory even with a low number of threads.  Running out
	      of  memory  or  swapping	will not improve decompression perfor‐
	      mance.

	      See --memlimit-compress=limit for possible ways to  specify  the
	      limit.   Setting limit to 0 resets the limit to the default sys‐
	      tem-specific value.

       -M limit, --memlimit=limit, --memory=limit
	      This  is	equivalent  to	specifying   --memlimit-compress=limit
	      --memlimit-decompress=limit --memlimit-mt-decompress=limit.

       --no-adjust
	      Display  an  error  and exit if the memory usage limit cannot be
	      met without adjusting settings that affect the  compressed  out‐
	      put.   That is, this prevents xz from switching the encoder from
	      multi-threaded mode to single-threaded mode  and	from  reducing
	      the  LZMA2  dictionary  size.  Even when this option is used the
	      number of threads may be reduced to meet the memory usage	 limit
	      as that won't affect the compressed output.

	      Automatic adjusting is always disabled when creating raw streams
	      (--format=raw).

       -T threads, --threads=threads
	      Specify the number of worker threads to use.  Setting threads to
	      a special value 0 makes xz use up to as many threads as the pro‐
	      cessor(s) on the system support.	The actual number  of  threads
	      can  be  fewer  than threads if the input file is not big enough
	      for threading with the given settings or if using	 more  threads
	      would exceed the memory usage limit.

	      The  single-threaded and multi-threaded compressors produce dif‐
	      ferent output.  Single-threaded compressor will give the	small‐
	      est  file	 size but only the output from the multi-threaded com‐
	      pressor can be decompressed  using  multiple  threads.   Setting
	      threads to 1 will use the single-threaded mode.  Setting threads
	      to any other value, including 0,	will  use  the	multi-threaded
	      compressor even if the system supports only one hardware thread.
	      (xz 5.2.x used single-threaded mode in this situation.)

	      To use multi-threaded mode with only one thread, set threads  to
	      +1.   The	 +  prefix  has no effect with values other than 1.  A
	      memory usage limit can still make xz switch  to  single-threaded
	      mode  unless  --no-adjust is used.  Support for the + prefix was
	      added in xz 5.4.0.

	      If an automatic number of threads has been requested and no mem‐
	      ory  usage  limit has been specified, then a system-specific de‐
	      fault soft limit will be used to possibly limit  the  number  of
	      threads.	 It is a soft limit in sense that it is ignored if the
	      number of threads becomes one, thus a soft limit will never stop
	      xz  from	compressing or decompressing.  This default soft limit
	      will not make xz switch  from  multi-threaded  mode  to  single-
	      threaded	 mode.	  The  active  limits  can  be	seen  with  xz
	      --info-memory.

	      Currently the only threading method is to split the  input  into
	      blocks and compress them independently from each other.  The de‐
	      fault block size depends on the compression  level  and  can  be
	      overridden with the --block-size=size option.

	      Threaded decompression only works on files that contain multiple
	      blocks with size information in block headers.  All large enough
	      files compressed in multi-threaded mode meet this condition, but
	      files  compressed	 in  single-threaded  mode   don't   even   if
	      --block-size=size has been used.

	      The  default  value for threads is 0.  In xz 5.4.x and older the
	      default is 1.

   Custom compressor filter chains
       A custom filter chain allows specifying the compression settings in de‐
       tail  instead  of  relying  on  the settings associated to the presets.
       When a custom filter chain is specified, preset options (-0 ... -9  and
       --extreme)  earlier on the command line are forgotten.  If a preset op‐
       tion is specified after one or more custom filter  chain	 options,  the
       new  preset  takes effect and the custom filter chain options specified
       earlier are forgotten.

       A filter chain is comparable to piping on the command line.  When  com‐
       pressing, the uncompressed input goes to the first filter, whose output
       goes to the next filter (if any).  The output of the last  filter  gets
       written	to  the compressed file.  The maximum number of filters in the
       chain is four, but typically a filter chain has only one	 or  two  fil‐
       ters.

       Many filters have limitations on where they can be in the filter chain:
       some filters can work only as the last filter in the chain,  some  only
       as  a non-last filter, and some work in any position in the chain.  De‐
       pending on the filter, this limitation is either inherent to the filter
       design or exists to prevent security issues.

       A  custom filter chain can be specified in two different ways.  The op‐
       tions --filters=filters and --filters1=filters  ...  --filters9=filters
       allow specifying an entire filter chain in one option using the liblzma
       filter string syntax.  Alternatively, a filter chain can	 be  specified
       by  using  one  or more individual filter options in the order they are
       wanted in the filter chain.  That is, the order of the individual  fil‐
       ter  options is significant!  When decoding raw streams (--format=raw),
       the filter chain must be specified in the same order as it  was	speci‐
       fied  when compressing.	Any individual filter or preset options speci‐
       fied before the full chain option (--filters=filters) will  be  forgot‐
       ten.  Individual filters specified after the full chain option will re‐
       set the filter chain.

       Both the full and individual filter options  take  filter-specific  op‐
       tions  as a comma-separated list.  Extra commas in options are ignored.
       Every option has a default value, so specify those you want to change.

       To see the whole filter chain and options, use xz  -vv  (that  is,  use
       --verbose twice).  This works also for viewing the filter chain options
       used by presets.

       --filters=filters
	      Specify the full filter chain or a preset in  a  single  option.
	      Each filter can be separated by spaces or two dashes (--).  fil‐
	      ters may need to be quoted on the shell command line  so	it  is
	      parsed  as  a  single option.  To denote options, use : or =.  A
	      preset can be prefixed with a - and followed with zero  or  more
	      flags.   The  only supported flag is e to apply the same options
	      as --extreme.

       --filters1=filters ... --filters9=filters
	      Specify up to nine additional filter chains  that	 can  be  used
	      with --block-list.

	      For  example,  when compressing an archive with executable files
	      followed by text files, the executable part could use  a	filter
	      chain with a BCJ filter and the text part only the LZMA2 filter.

       --filters-help
	      Display  a  help	message	 describing how to specify presets and
	      custom filter chains in the --filters and --filters1=filters ...
	      --filters9=filters options, and exit successfully.

       --lzma1[=options]
       --lzma2[=options]
	      Add  LZMA1  or  LZMA2 filter to the filter chain.	 These filters
	      can be used only as the last filter in the chain.

	      LZMA1 is a legacy filter, which is supported almost  solely  due
	      to  the  legacy  .lzma  file  format, which supports only LZMA1.
	      LZMA2 is an updated version of LZMA1 to fix some	practical  is‐
	      sues  of	LZMA1.	 The .xz format uses LZMA2 and doesn't support
	      LZMA1 at all.  Compression speed and ratios of LZMA1  and	 LZMA2
	      are practically the same.

	      LZMA1 and LZMA2 share the same set of options:

	      preset=preset
		     Reset  all LZMA1 or LZMA2 options to preset.  Preset con‐
		     sist of an integer, which may be followed by  single-let‐
		     ter  preset  modifiers.   The integer can be from 0 to 9,
		     matching the command line options -0 ...  -9.   The  only
		     supported	modifier  is  currently e, which matches --ex‐
		     treme.  If no preset is specified, the default values  of
		     LZMA1 or LZMA2 options are taken from the preset 6.

	      dict=size
		     Dictionary (history buffer) size indicates how many bytes
		     of the recently processed uncompressed data  is  kept  in
		     memory.   The  algorithm tries to find repeating byte se‐
		     quences (matches) in the uncompressed data,  and  replace
		     them with references to the data currently in the dictio‐
		     nary.  The bigger	the  dictionary,  the  higher  is  the
		     chance to find a match.  Thus, increasing dictionary size
		     usually improves compression ratio, but a dictionary big‐
		     ger than the uncompressed file is waste of memory.

		     Typical  dictionary  size	is from 64 KiB to 64 MiB.  The
		     minimum is 4 KiB.	The maximum for	 compression  is  cur‐
		     rently 1.5 GiB (1536 MiB).	 The decompressor already sup‐
		     ports dictionaries up to one byte less than 4 GiB,	 which
		     is the maximum for the LZMA1 and LZMA2 stream formats.

		     Dictionary	 size and match finder (mf) together determine
		     the memory usage of the LZMA1 or LZMA2 encoder.  The same
		     (or bigger) dictionary size is required for decompressing
		     that was used when compressing, thus the memory usage  of
		     the  decoder  is  determined  by the dictionary size used
		     when compressing.	The .xz headers store  the  dictionary
		     size  either  as 2^n or 2^n + 2^(n-1), so these sizes are
		     somewhat preferred for compression.  Other sizes will get
		     rounded up when stored in the .xz headers.

	      lc=lc  Specify  the number of literal context bits.  The minimum
		     is 0 and the maximum is 4; the default is	3.   In	 addi‐
		     tion, the sum of lc and lp must not exceed 4.

		     All  bytes	 that cannot be encoded as matches are encoded
		     as literals.  That is, literals are  simply  8-bit	 bytes
		     that are encoded one at a time.

		     The  literal  coding makes an assumption that the highest
		     lc bits of the previous uncompressed byte correlate  with
		     the  next byte.  For example, in typical English text, an
		     upper-case letter is often followed by a lower-case  let‐
		     ter,  and	a lower-case letter is usually followed by an‐
		     other lower-case letter.  In the US-ASCII character  set,
		     the highest three bits are 010 for upper-case letters and
		     011 for lower-case letters.  When lc is at least  3,  the
		     literal coding can take advantage of this property in the
		     uncompressed data.

		     The default value (3) is usually good.  If you want maxi‐
		     mum compression, test lc=4.  Sometimes it helps a little,
		     and sometimes it makes compression worse.	If it makes it
		     worse, test lc=2 too.

	      lp=lp  Specify the number of literal position bits.  The minimum
		     is 0 and the maximum is 4; the default is 0.

		     Lp affects what kind of  alignment	 in  the  uncompressed
		     data is assumed when encoding literals.  See pb below for
		     more information about alignment.

	      pb=pb  Specify the number of position bits.  The	minimum	 is  0
		     and the maximum is 4; the default is 2.

		     Pb	 affects  what	kind  of alignment in the uncompressed
		     data is assumed in general.  The default means  four-byte
		     alignment (2^pb=2^2=4), which is often a good choice when
		     there's no better guess.

		     When the alignment is known, setting pb  accordingly  may
		     reduce  the  file	size a little.	For example, with text
		     files having one-byte  alignment  (US-ASCII,  ISO-8859-*,
		     UTF-8),  setting  pb=0  can improve compression slightly.
		     For UTF-16 text, pb=1 is a good choice.  If the alignment
		     is	 an  odd  number  like 3 bytes, pb=0 might be the best
		     choice.

		     Even though the assumed alignment can be adjusted with pb
		     and  lp,  LZMA1  and  LZMA2  still slightly favor 16-byte
		     alignment.	 It might be worth taking  into	 account  when
		     designing	file  formats that are likely to be often com‐
		     pressed with LZMA1 or LZMA2.

	      mf=mf  Match finder has a major effect on encoder speed,	memory
		     usage,  and  compression ratio.  Usually Hash Chain match
		     finders are faster than Binary Tree match	finders.   The
		     default  depends  on the preset: 0 uses hc3, 1–3 use hc4,
		     and the rest use bt4.

		     The following match finders are  supported.   The	memory
		     usage  formulas below are rough approximations, which are
		     closest to the reality when dict is a power of two.

		     hc3    Hash Chain with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 7.5 (if dict <= 16 MiB);
			    dict * 5.5 + 64 MiB (if dict > 16 MiB)

		     hc4    Hash Chain with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 7.5 (if dict <= 32 MiB);
			    dict * 6.5 (if dict > 32 MiB)

		     bt2    Binary Tree with 2-byte hashing
			    Minimum value for nice: 2
			    Memory usage: dict * 9.5

		     bt3    Binary Tree with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 11.5 (if dict <= 16 MiB);
			    dict * 9.5 + 64 MiB (if dict > 16 MiB)

		     bt4    Binary Tree with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 11.5 (if dict <= 32 MiB);
			    dict * 10.5 (if dict > 32 MiB)

	      mode=mode
		     Compression mode specifies the method to analyze the data
		     produced  by  the match finder.  Supported modes are fast
		     and normal.  The default is fast for presets 0–3 and nor‐
		     mal for presets 4–9.

		     Usually  fast  is	used with Hash Chain match finders and
		     normal with Binary Tree match finders.  This is also what
		     the presets do.

	      nice=nice
		     Specify  what  is	considered  to	be a nice length for a
		     match.  Once a match of at least nice bytes is found, the
		     algorithm stops looking for possibly better matches.

		     Nice can be 2–273 bytes.  Higher values tend to give bet‐
		     ter compression ratio at the expense of speed.   The  de‐
		     fault depends on the preset.

	      depth=depth
		     Specify  the  maximum  search  depth in the match finder.
		     The default is the special value of 0,  which  makes  the
		     compressor determine a reasonable depth from mf and nice.

		     Reasonable depth for Hash Chains is 4–100 and 16–1000 for
		     Binary Trees.  Using very high values for depth can  make
		     the  encoder  extremely slow with some files.  Avoid set‐
		     ting the depth over 1000 unless you are prepared  to  in‐
		     terrupt  the  compression	in  case  it is taking far too
		     long.

	      When decoding raw streams (--format=raw), LZMA2 needs  only  the
	      dictionary size.	LZMA1 needs also lc, lp, and pb.

       --x86[=options]
       --arm[=options]
       --armthumb[=options]
       --arm64[=options]
       --powerpc[=options]
       --ia64[=options]
       --sparc[=options]
       --riscv[=options]
	      Add  a branch/call/jump (BCJ) filter to the filter chain.	 These
	      filters can be used only as a  non-last  filter  in  the	filter
	      chain.

	      A	 BCJ filter converts relative addresses in the machine code to
	      their absolute counterparts.  This doesn't change	 the  size  of
	      the  data	 but  it increases redundancy, which can help LZMA2 to
	      produce 0–15 % smaller .xz file.	The BCJ filters are always re‐
	      versible,	 so  using a BCJ filter for wrong type of data doesn't
	      cause any data loss, although it may make the compression	 ratio
	      slightly	worse.	 The  BCJ filters are very fast and use an in‐
	      significant amount of memory.

	      These BCJ filters have known problems related to the compression
	      ratio:

	      •	 Some  types of files containing executable code (for example,
		 object files, static libraries,  and  Linux  kernel  modules)
		 have  the  addresses  in  the instructions filled with filler
		 values.  These BCJ filters will still do the address  conver‐
		 sion, which will make the compression worse with these files.

	      •	 If a BCJ filter is applied on an archive, it is possible that
		 it makes the compression ratio worse than  not	 using	a  BCJ
		 filter.   For example, if there are similar or even identical
		 executables then filtering will likely make  the  files  less
		 similar  and thus compression is worse.  The contents of non-
		 executable files in the same  archive	can  matter  too.   In
		 practice  one has to try with and without a BCJ filter to see
		 which is better in each situation.

	      Different instruction sets have different	 alignment:  the  exe‐
	      cutable  file must be aligned to a multiple of this value in the
	      input data to make the filter work.

		     tab(;); l n l l n l.  Filter;Alignment;Notes x86;1;32-bit
		     or	  64-bit  x86  ARM;4;  ARM-Thumb;2;  ARM64;4;4096-byte
		     alignment is best PowerPC;4;Big endian only IA-64;16;Ita‐
		     nium SPARC;4; RISC-V;2;

	      Since  the  BCJ-filtered	data is usually compressed with LZMA2,
	      the compression ratio may be improved slightly if the LZMA2  op‐
	      tions are set to match the alignment of the selected BCJ filter.
	      Examples:

	      •	 IA-64 filter has 16-byte alignment so pb=4,lp=4,lc=0 is  good
		 with LZMA2 (2^4=16).

	      •	 RISC-V	 code  has  2-byte  or	4-byte	alignment depending on
		 whether the file contains 16-bit compressed instructions (the
		 C   extension).    When   16-bit   instructions   are	 used,
		 pb=2,lp=1,lc=3 or pb=1,lp=1,lc=3 is good.   When  16-bit  in‐
		 structions aren't present, pb=2,lp=2,lc=2 is the best.	 read‐
		 elf -h can be used to check if "RVC" appears on  the  "Flags"
		 line.

	      •	 ARM64 is always 4-byte aligned so pb=2,lp=2,lc=2 is the best.

	      •	 The  x86  filter is an exception.  It's usually good to stick
		 to LZMA2's defaults (pb=2,lp=0,lc=3) when compressing x86 ex‐
		 ecutables.

	      All BCJ filters support the same options:

	      start=offset
		     Specify the start offset that is used when converting be‐
		     tween relative and absolute addresses.  The  offset  must
		     be a multiple of the alignment of the filter (see the ta‐
		     ble above).  The default is zero.	In practice,  the  de‐
		     fault is good; specifying a custom offset is almost never
		     useful.

       --delta[=options]
	      Add the Delta filter to the filter chain.	 The Delta filter  can
	      be only used as a non-last filter in the filter chain.

	      Currently	 only simple byte-wise delta calculation is supported.
	      It can be useful when  compressing,  for	example,  uncompressed
	      bitmap  images or uncompressed PCM audio.	 However, special pur‐
	      pose algorithms may give significantly better results than Delta
	      +	 LZMA2.	  This is true especially with audio, which compresses
	      faster and better, for example, with flac(1).

	      Supported options:

	      dist=distance
		     Specify the distance of the delta calculation  in	bytes.
		     distance must be 1–256.  The default is 1.

		     For example, with dist=2 and eight-byte input A1 B1 A2 B3
		     A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

   Other options
       -q, --quiet
	      Suppress warnings and notices.  Specify this twice  to  suppress
	      errors too.  This option has no effect on the exit status.  That
	      is, even if a warning was suppressed, the exit status  to	 indi‐
	      cate a warning is still used.

       -v, --verbose
	      Be  verbose.   If	 standard error is connected to a terminal, xz
	      will display a progress indicator.  Specifying  --verbose	 twice
	      will give even more verbose output.

	      The progress indicator shows the following information:

	      •	 Completion  percentage is shown if the size of the input file
		 is known.  That is, the percentage cannot be shown in pipes.

	      •	 Amount of compressed data produced (compressing) or  consumed
		 (decompressing).

	      •	 Amount	 of  uncompressed  data consumed (compressing) or pro‐
		 duced (decompressing).

	      •	 Compression ratio, which is calculated by dividing the amount
		 of  compressed	 data processed so far by the amount of uncom‐
		 pressed data processed so far.

	      •	 Compression or decompression speed.  This is measured as  the
		 amount	 of  uncompressed  data consumed (compression) or pro‐
		 duced (decompression) per second.  It is shown	 after	a  few
		 seconds have passed since xz started processing the file.

	      •	 Elapsed time in the format M:SS or H:MM:SS.

	      •	 Estimated  remaining  time is shown only when the size of the
		 input file is known and a  couple  of	seconds	 have  already
		 passed	 since	xz  started  processing the file.  The time is
		 shown in a less precise format which never  has  any  colons,
		 for example, 2 min 30 s.

	      When  standard  error  is not a terminal, --verbose will make xz
	      print the filename, compressed size, uncompressed size, compres‐
	      sion  ratio,  and	 possibly also the speed and elapsed time on a
	      single line to standard error after compressing or decompressing
	      the file.	 The speed and elapsed time are included only when the
	      operation took at least a few seconds.  If the operation	didn't
	      finish,  for example, due to user interruption, also the comple‐
	      tion percentage is printed if the size  of  the  input  file  is
	      known.

       -Q, --no-warn
	      Don't set the exit status to 2 even if a condition worth a warn‐
	      ing was detected.	 This  option  doesn't	affect	the  verbosity
	      level,  thus  both  --quiet and --no-warn have to be used to not
	      display warnings and to not alter the exit status.

       --robot
	      Print messages in a machine-parsable format.  This  is  intended
	      to  ease	writing	 frontends  that want to use xz instead of li‐
	      blzma, which may be the case with various scripts.   The	output
	      with  this  option  enabled  is meant to be stable across xz re‐
	      leases.  See the section ROBOT MODE for details.

       --info-memory
	      Display, in human-readable  format,  how	much  physical	memory
	      (RAM)  and  how  many processor threads xz thinks the system has
	      and the memory usage limits for compression  and	decompression,
	      and exit successfully.

       -h, --help
	      Display  a  help	message	 describing the most commonly used op‐
	      tions, and exit successfully.

       -H, --long-help
	      Display a help message describing all features of xz,  and  exit
	      successfully

       -V, --version
	      Display  the  version number of xz and liblzma in human readable
	      format.  To get machine-parsable output, specify --robot	before
	      --version.

ROBOT MODE
       The robot mode is activated with the --robot option.  It makes the out‐
       put of xz easier to parse by other programs.  Currently --robot is sup‐
       ported  only  together  with --list, --filters-help, --info-memory, and
       --version.  It will be supported for compression and  decompression  in
       the future.

   List mode
       xz --robot --list uses tab-separated output.  The first column of every
       line has a string that indicates the type of the information  found  on
       that line:

       name   This is always the first line when starting to list a file.  The
	      second column on the line is the filename.

       file   This line contains overall information about the .xz file.  This
	      line is always printed after the name line.

       stream This line type is used only when --verbose was specified.	 There
	      are as many stream lines as there are streams in the .xz file.

       block  This line type is used only when --verbose was specified.	 There
	      are  as  many  block  lines as there are blocks in the .xz file.
	      The block lines are shown after all the stream lines;  different
	      line types are not interleaved.

       summary
	      This  line type is used only when --verbose was specified twice.
	      This line is printed after all block lines.  Like the file line,
	      the  summary  line  contains  overall  information about the .xz
	      file.

       totals This line is always the very last line of the list  output.   It
	      shows the total counts and sizes.

       The columns of the file lines:
	      2.  Number of streams in the file
	      3.  Total number of blocks in the stream(s)
	      4.  Compressed size of the file
	      5.  Uncompressed size of the file
	      6.  Compression  ratio,  for  example,  0.123.  If ratio is over
		  9.999, three dashes (---) are displayed instead of  the  ra‐
		  tio.
	      7.  Comma-separated  list of integrity check names.  The follow‐
		  ing strings are used for the known check types: None, CRC32,
		  CRC64,  and  SHA-256.	 For unknown check types, Unknown-N is
		  used, where N is the Check ID as a decimal  number  (one  or
		  two digits).
	      8.  Total size of stream padding in the file

       The columns of the stream lines:
	      2.  Stream number (the first stream is 1)
	      3.  Number of blocks in the stream
	      4.  Compressed start offset
	      5.  Uncompressed start offset
	      6.  Compressed size (does not include stream padding)
	      7.  Uncompressed size
	      8.  Compression ratio
	      9.  Name of the integrity check
	      10. Size of stream padding

       The columns of the block lines:
	      2.  Number of the stream containing this block
	      3.  Block	 number	 relative  to the beginning of the stream (the
		  first block is 1)
	      4.  Block number relative to the beginning of the file
	      5.  Compressed start offset relative to  the  beginning  of  the
		  file
	      6.  Uncompressed	start  offset relative to the beginning of the
		  file
	      7.  Total compressed size of the block (includes headers)
	      8.  Uncompressed size
	      9.  Compression ratio
	      10. Name of the integrity check

       If --verbose was specified twice, additional columns  are  included  on
       the  block lines.  These are not displayed with a single --verbose, be‐
       cause getting this information requires many  seeks  and	 can  thus  be
       slow:
	      11. Value of the integrity check in hexadecimal
	      12. Block header size
	      13. Block	 flags:	 c  indicates that compressed size is present,
		  and u indicates that uncompressed size is present.   If  the
		  flag	is  not	 set,  a dash (-) is shown instead to keep the
		  string length fixed.	New flags may be added to the  end  of
		  the string in the future.
	      14. Size	of  the	 actual compressed data in the block (this ex‐
		  cludes the block header, block padding, and check fields)
	      15. Amount of memory (in	bytes)	required  to  decompress  this
		  block with this xz version
	      16. Filter  chain.   Note	 that most of the options used at com‐
		  pression time cannot be known, because only the options that
		  are needed for decompression are stored in the .xz headers.

       The columns of the summary lines:
	      2.  Amount of memory (in bytes) required to decompress this file
		  with this xz version
	      3.  yes or no indicating if all block  headers  have  both  com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      4.  Minimum xz version required to decompress the file

       The columns of the totals line:
	      2.  Number of streams
	      3.  Number of blocks
	      4.  Compressed size
	      5.  Uncompressed size
	      6.  Average compression ratio
	      7.  Comma-separated  list	 of  integrity	check  names that were
		  present in the files
	      8.  Stream padding size
	      9.  Number of files.  This is here to keep the order of the ear‐
		  lier columns the same as on file lines.

       If  --verbose  was  specified twice, additional columns are included on
       the totals line:
	      10. Maximum amount of memory (in bytes) required	to  decompress
		  the files with this xz version
	      11. yes  or  no  indicating  if all block headers have both com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      12. Minimum xz version required to decompress the file

       Future versions may add new line types and new columns can be added  to
       the existing line types, but the existing columns won't be changed.

   Filters help
       xz --robot --filters-help prints the supported filters in the following
       format:

       filter:option=<value>,option=<value>...

       filter Name of the filter

       option Name of a filter specific option

       value  Numeric value ranges appear as <min-max>.	 String value  choices
	      are shown within < > and separated by a | character.

       Each filter is printed on its own line.

   Memory limit information
       xz  --robot  --info-memory prints a single line with multiple tab-sepa‐
       rated columns:

       1.  Total amount of physical memory (RAM) in bytes.

       2.  Memory usage limit for compression in bytes	(--memlimit-compress).
	   A  special  value of 0 indicates the default setting which for sin‐
	   gle-threaded mode is the same as no limit.

       3.  Memory usage limit for decompression	 in  bytes  (--memlimit-decom‐
	   press).   A	special value of 0 indicates the default setting which
	   for single-threaded mode is the same as no limit.

       4.  Since xz 5.3.4alpha: Memory usage for multi-threaded	 decompression
	   in  bytes (--memlimit-mt-decompress).  This is never zero because a
	   system-specific default value shown in the column 5 is used	if  no
	   limit  has  been  specified explicitly.  This is also never greater
	   than the value in the column 3 even if  a  larger  value  has  been
	   specified with --memlimit-mt-decompress.

       5.  Since  xz  5.3.4alpha: A system-specific default memory usage limit
	   that is used to limit the number of threads when  compressing  with
	   an  automatic  number  of threads (--threads=0) and no memory usage
	   limit has been specified (--memlimit-compress).  This is also  used
	   as the default value for --memlimit-mt-decompress.

       6.  Since xz 5.3.4alpha: Number of available processor threads.

       In  the	future,	 the  output of xz --robot --info-memory may have more
       columns, but never more than a single line.

   Version
       xz --robot --version prints the version number of xz and liblzma in the
       following format:

       XZ_VERSION=XYYYZZZS
       LIBLZMA_VERSION=XYYYZZZS

       X      Major version.

       YYY    Minor  version.  Even numbers are stable.	 Odd numbers are alpha
	      or beta versions.

       ZZZ    Patch level for stable releases or just a counter	 for  develop‐
	      ment releases.

       S      Stability.  0 is alpha, 1 is beta, and 2 is stable.  S should be
	      always 2 when YYY is even.

       XYYYZZZS are the same on both lines if xz and liblzma are from the same
       XZ Utils release.

       Examples: 4.999.9beta is 49990091 and 5.0.0 is 50000002.

EXIT STATUS
       0      All is good.

       1      An error occurred.

       2      Something	 worth	a  warning  occurred, but no actual errors oc‐
	      curred.

       Notices (not warnings or errors) printed on standard error don't affect
       the exit status.

ENVIRONMENT
       xz  parses  space-separated lists of options from the environment vari‐
       ables XZ_DEFAULTS and XZ_OPT, in this order, before parsing the options
       from  the command line.	Note that only options are parsed from the en‐
       vironment variables; all non-options are silently ignored.  Parsing  is
       done  with getopt_long(3) which is used also for the command line argu‐
       ments.

       XZ_DEFAULTS
	      User-specific or system-wide default options.  Typically this is
	      set in a shell initialization script to enable xz's memory usage
	      limiter by default.  Excluding shell initialization scripts  and
	      similar  special	cases,	scripts must never set or unset XZ_DE‐
	      FAULTS.

       XZ_OPT This is for passing options to xz when it is not possible to set
	      the  options  directly on the xz command line.  This is the case
	      when xz is run by a script or tool, for example, GNU tar(1):

		     XZ_OPT=-2v tar caf foo.tar.xz foo

	      Scripts may use XZ_OPT, for example, to set script-specific  de‐
	      fault  compression  options.   It	 is still recommended to allow
	      users to override XZ_OPT if that is reasonable.  For example, in
	      sh(1) scripts one may use something like this:

		     XZ_OPT=${XZ_OPT-"-7e"}
		     export XZ_OPT

LZMA UTILS COMPATIBILITY
       The  command  line  syntax of xz is practically a superset of lzma, un‐
       lzma, and lzcat as found from LZMA Utils 4.32.x.	 In most cases, it  is
       possible	 to replace LZMA Utils with XZ Utils without breaking existing
       scripts.	 There are some incompatibilities though, which may  sometimes
       cause problems.

   Compression preset levels
       The  numbering  of the compression level presets is not identical in xz
       and LZMA Utils.	The most important difference is how dictionary	 sizes
       are  mapped  to different presets.  Dictionary size is roughly equal to
       the decompressor memory usage.

	      tab(;); c c c c n n.  Level;xz;LZMA Utils	 -0;256	 KiB;N/A  -1;1
	      MiB;64  KiB  -2;2 MiB;1 MiB -3;4 MiB;512 KiB -4;4 MiB;1 MiB -5;8
	      MiB;2 MiB -6;8 MiB;4 MiB -7;16 MiB;8 MiB -8;32 MiB;16 MiB	 -9;64
	      MiB;32 MiB

       The dictionary size differences affect the compressor memory usage too,
       but there are some other differences between LZMA Utils and  XZ	Utils,
       which make the difference even bigger:

	      tab(;);  c  c  c c n n.  Level;xz;LZMA Utils 4.32.x -0;3 MiB;N/A
	      -1;9 MiB;2 MiB -2;17 MiB;12 MiB -3;32 MiB;12  MiB	 -4;48	MiB;16
	      MiB  -5;94  MiB;26 MiB -6;94 MiB;45 MiB -7;186 MiB;83 MiB -8;370
	      MiB;159 MiB -9;674 MiB;311 MiB

       The default preset level in LZMA Utils is -7 while in XZ	 Utils	it  is
       -6, so both use an 8 MiB dictionary by default.

   Streamed vs. non-streamed .lzma files
       The  uncompressed  size	of the file can be stored in the .lzma header.
       LZMA Utils does that when compressing regular files.   The  alternative
       is  to  mark  that  uncompressed size is unknown and use end-of-payload
       marker to indicate where the decompressor should stop.  LZMA Utils uses
       this  method when uncompressed size isn't known, which is the case, for
       example, in pipes.

       xz supports decompressing .lzma files with  or  without	end-of-payload
       marker,	but  all  .lzma	 files	created	 by xz will use end-of-payload
       marker and have uncompressed  size  marked  as  unknown	in  the	 .lzma
       header.	 This may be a problem in some uncommon situations.  For exam‐
       ple, a .lzma decompressor in an embedded device might  work  only  with
       files  that have known uncompressed size.  If you hit this problem, you
       need to use LZMA Utils or LZMA SDK to create .lzma files with known un‐
       compressed size.

   Unsupported .lzma files
       The .lzma format allows lc values up to 8, and lp values up to 4.  LZMA
       Utils can decompress files with any lc and lp, but always creates files
       with  lc=3  and	lp=0.  Creating files with other lc and lp is possible
       with xz and with LZMA SDK.

       The implementation of the LZMA1 filter in liblzma requires that the sum
       of  lc  and lp must not exceed 4.  Thus, .lzma files, which exceed this
       limitation, cannot be decompressed with xz.

       LZMA Utils creates only .lzma files which have a dictionary size of 2^n
       (a power of 2) but accepts files with any dictionary size.  liblzma ac‐
       cepts only .lzma files which have a dictionary size of  2^n  or	2^n  +
       2^(n-1).	  This	is  to	decrease  false positives when detecting .lzma
       files.

       These limitations shouldn't be a problem in practice, since practically
       all  .lzma  files  have been compressed with settings that liblzma will
       accept.

   Trailing garbage
       When decompressing, LZMA Utils silently	ignore	everything  after  the
       first  .lzma  stream.   In  most	 situations, this is a bug.  This also
       means that LZMA Utils don't support  decompressing  concatenated	 .lzma
       files.

       If  there  is  data left after the first .lzma stream, xz considers the
       file to be corrupt unless --single-stream was used.  This may break ob‐
       scure scripts which have assumed that trailing garbage is ignored.

NOTES
   Compressed output may vary
       The  exact  compressed output produced from the same uncompressed input
       file may vary between XZ Utils versions even if compression options are
       identical.  This is because the encoder can be improved (faster or bet‐
       ter compression) without affecting the file  format.   The  output  can
       vary  even  between  different  builds of the same XZ Utils version, if
       different build options are used.

       The above means that once --rsyncable has been implemented, the result‐
       ing  files won't necessarily be rsyncable unless both old and new files
       have been compressed with the same xz version.	This  problem  can  be
       fixed if a part of the encoder implementation is frozen to keep rsynca‐
       ble output stable across xz versions.

   Embedded .xz decompressors
       Embedded .xz decompressor implementations like XZ Embedded don't neces‐
       sarily support files created with integrity check types other than none
       and  crc32.   Since  the	 default  is  --check=crc64,  you   must   use
       --check=none or --check=crc32 when creating files for embedded systems.

       Outside	embedded systems, all .xz format decompressors support all the
       check types, or at least are able to decompress the file without	 veri‐
       fying the integrity check if the particular check is not supported.

       XZ  Embedded supports BCJ filters, but only with the default start off‐
       set.

EXAMPLES
   Basics
       Compress the file foo into foo.xz using the default  compression	 level
       (-6), and remove foo if compression is successful:

	      xz foo

       Decompress  bar.xz  into bar and don't remove bar.xz even if decompres‐
       sion is successful:

	      xz -dk bar.xz

       Create baz.tar.xz with the preset -4e (-4 --extreme), which  is	slower
       than  the  default -6, but needs less memory for compression and decom‐
       pression (48 MiB and 5 MiB, respectively):

	      tar cf - baz | xz -4e > baz.tar.xz

       A mix of compressed and uncompressed files can be decompressed to stan‐
       dard output with a single command:

	      xz -dcf a.txt b.txt.xz c.txt d.txt.lzma > abcd.txt

   Parallel compression of many files
       On  GNU	and *BSD, find(1) and xargs(1) can be used to parallelize com‐
       pression of many files:

	      find . -type f \! -name '*.xz' -print0 \
		  | xargs -0r -P4 -n16 xz -T1

       The -P option to xargs(1) sets the number  of  parallel	xz  processes.
       The best value for the -n option depends on how many files there are to
       be compressed.  If there are only a couple of files, the	 value	should
       probably be 1; with tens of thousands of files, 100 or even more may be
       appropriate to reduce the number of xz  processes  that	xargs(1)  will
       eventually create.

       The option -T1 for xz is there to force it to single-threaded mode, be‐
       cause xargs(1) is used to control the amount of parallelization.

   Robot mode
       Calculate how many bytes have been saved	 in  total  after  compressing
       multiple files:

	      xz --robot --list *.xz | awk '/^totals/{print $5-$4}'

       A  script may want to know that it is using new enough xz.  The follow‐
       ing sh(1) script checks that the version number of the xz  tool	is  at
       least  5.0.0.   This method is compatible with old beta versions, which
       didn't support the --robot option:

	      if ! eval "$(xz --robot --version 2> /dev/null)" ||
		      [ "$XZ_VERSION" -lt 50000002 ]; then
		  echo "Your xz is too old."
	      fi
	      unset XZ_VERSION LIBLZMA_VERSION

       Set a memory usage limit for decompression using XZ_OPT, but if a limit
       has already been set, don't increase it:

	      NEWLIM=$((123 << 20))  # 123 MiB
	      OLDLIM=$(xz --robot --info-memory | cut -f3)
	      if [ $OLDLIM -eq 0 -o $OLDLIM -gt $NEWLIM ]; then
		  XZ_OPT="$XZ_OPT --memlimit-decompress=$NEWLIM"
		  export XZ_OPT
	      fi

   Custom compressor filter chains
       The  simplest  use for custom filter chains is customizing a LZMA2 pre‐
       set.  This can be useful, because the presets cover only	 a  subset  of
       the potentially useful combinations of compression settings.

       The  CompCPU columns of the tables from the descriptions of the options
       -0 ... -9 and --extreme are  useful  when  customizing  LZMA2  presets.
       Here are the relevant parts collected from those two tables:

	      tab(;);  c  c n n.  Preset;CompCPU -0;0 -1;1 -2;2 -3;3 -4;4 -5;5
	      -6;6 -5e;7 -6e;8

       If you know that a file requires somewhat big dictionary (for  example,
       32 MiB)	to  compress well, but you want to compress it quicker than xz
       -8 would do, a preset with a low CompCPU value (for example, 1) can  be
       modified to use a bigger dictionary:

	      xz --lzma2=preset=1,dict=32MiB foo.tar

       With  certain  files,  the above command may be faster than xz -6 while
       compressing significantly better.  However, it must be emphasized  that
       only some files benefit from a big dictionary while keeping the CompCPU
       value low.  The most obvious situation, where a big dictionary can help
       a  lot,	is  an archive containing very similar files of at least a few
       megabytes each.	The dictionary size has	 to  be	 significantly	bigger
       than  any  individual file to allow LZMA2 to take full advantage of the
       similarities between consecutive files.

       If very high compressor and decompressor memory usage is fine, and  the
       file  being compressed is at least several hundred megabytes, it may be
       useful to use an even bigger dictionary than the	 64  MiB  that	xz  -9
       would use:

	      xz -vv --lzma2=dict=192MiB big_foo.tar

       Using -vv (--verbose --verbose) like in the above example can be useful
       to see the memory requirements of the compressor and decompressor.  Re‐
       member that using a dictionary bigger than the size of the uncompressed
       file is waste of memory, so the above command isn't  useful  for	 small
       files.

       Sometimes  the  compression  time  doesn't matter, but the decompressor
       memory usage has to be kept low, for example, to make  it  possible  to
       decompress  the file on an embedded system.  The following command uses
       -6e (-6 --extreme) as a base and sets the dictionary  to	 only  64 KiB.
       The  resulting  file  can  be decompressed with XZ Embedded (that's why
       there is --check=crc32) using about 100 KiB of memory.

	      xz --check=crc32 --lzma2=preset=6e,dict=64KiB foo

       If you want to squeeze out as many bytes	 as  possible,	adjusting  the
       number  of  literal  context bits (lc) and number of position bits (pb)
       can sometimes help.  Adjusting the number of literal position bits (lp)
       might help too, but usually lc and pb are more important.  For example,
       a source code archive contains mostly US-ASCII text, so something  like
       the following might give slightly (like 0.1 %) smaller file than xz -6e
       (try also without lc=4):

	      xz --lzma2=preset=6e,pb=0,lc=4 source_code.tar

       Using another filter together with LZMA2 can improve  compression  with
       certain file types.  For example, to compress a x86-32 or x86-64 shared
       library using the x86 BCJ filter:

	      xz --x86 --lzma2 libfoo.so

       Note that the order of the filter options is significant.  If --x86  is
       specified after --lzma2, xz will give an error, because there cannot be
       any filter after LZMA2, and also because the x86 BCJ filter  cannot  be
       used as the last filter in the chain.

       The  Delta filter together with LZMA2 can give good results with bitmap
       images.	It should usually beat PNG, which has a few more advanced fil‐
       ters than simple delta but uses Deflate for the actual compression.

       The  image  has to be saved in uncompressed format, for example, as un‐
       compressed TIFF.	 The distance parameter of the Delta filter is set  to
       match  the number of bytes per pixel in the image.  For example, 24-bit
       RGB bitmap needs dist=3, and it is also good to pass pb=0 to  LZMA2  to
       accommodate the three-byte alignment:

	      xz --delta=dist=3 --lzma2=pb=0 foo.tiff

       If  multiple  images  have been put into a single archive (for example,
       .tar), the Delta filter will work on that too as	 long  as  all	images
       have the same number of bytes per pixel.

SEE ALSO
       xzdec(1),   xzdiff(1),	xzgrep(1),   xzless(1),	  xzmore(1),  gzip(1),
       bzip2(1), 7z(1)

       XZ Utils: <https://tukaani.org/xz/>
       XZ Embedded: <https://tukaani.org/xz/embedded.html>
       LZMA SDK: <https://7-zip.org/sdk.html>



Tukaani				  2024-12-30				 XZ(1)

XZDIFF(1)			   XZ Utils			     XZDIFF(1)



NAME
       xzcmp, xzdiff, lzcmp, lzdiff - compare compressed files

SYNOPSIS
       xzcmp [option...]  file1 [file2]
       xzdiff ...
       lzcmp ...
       lzdiff ...

DESCRIPTION
       xzcmp  and  xzdiff  compare uncompressed contents of two files.	Uncom‐
       pressed data and options are passed to cmp(1) or diff(1) unless	--help
       or --version is specified.

       If  both	 file1 and file2 are specified, they can be uncompressed files
       or files in formats that xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1)  can decompress.	The required decompression commands are deter‐
       mined from the filename suffixes of file1 and file2.  A	file  with  an
       unknown suffix is assumed to be either uncompressed or in a format that
       xz(1) can decompress.

       If only one filename is provided, file1 must have a suffix  of  a  sup‐
       ported compression format and the name for file2 is assumed to be file1
       with the compression format suffix removed.

       The commands lzcmp and lzdiff are provided for  backward	 compatibility
       with LZMA Utils.

EXIT STATUS
       If  a  decompression error occurs, the exit status is 2.	 Otherwise the
       exit status of cmp(1) or diff(1) is used.

SEE ALSO
       cmp(1), diff(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1)



Tukaani				  2024-02-13			     XZDIFF(1)

XZDEC(1)			   XZ Utils			      XZDEC(1)



NAME
       xzdec, lzmadec - Small .xz and .lzma decompressors

SYNOPSIS
       xzdec [option...]  [file...]
       lzmadec [option...]  [file...]

DESCRIPTION
       xzdec is a liblzma-based decompression-only tool for .xz (and only .xz)
       files.  xzdec is intended to work as a drop-in replacement for xz(1) in
       the  most  common  situations where a script has been written to use xz
       --decompress --stdout (and possibly a few other commonly used  options)
       to decompress .xz files.	 lzmadec is identical to xzdec except that lz‐
       madec supports .lzma files instead of .xz files.

       To reduce the size of the  executable,  xzdec  doesn't  support	multi‐
       threading  or  localization,  and doesn't read options from XZ_DEFAULTS
       and XZ_OPT environment variables.  xzdec doesn't support displaying in‐
       termediate progress information: sending SIGINFO to xzdec does nothing,
       but sending  SIGUSR1  terminates	 the  process  instead	of  displaying
       progress information.

OPTIONS
       -d, --decompress, --uncompress
	      Ignored for xz(1) compatibility.	xzdec supports only decompres‐
	      sion.

       -k, --keep
	      Ignored for xz(1) compatibility.	xzdec never creates or removes
	      any files.

       -c, --stdout, --to-stdout
	      Ignored for xz(1) compatibility.	xzdec always writes the decom‐
	      pressed data to standard output.

       -q, --quiet
	      Specifying this once does nothing since xzdec never displays any
	      warnings or notices.  Specify this twice to suppress errors.

       -Q, --no-warn
	      Ignored for xz(1) compatibility.	xzdec never uses the exit sta‐
	      tus 2.

       -h, --help
	      Display a help message and exit successfully.

       -V, --version
	      Display the version number of xzdec and liblzma.

EXIT STATUS
       0      All was good.

       1      An error occurred.

       xzdec doesn't have any warning messages like xz(1) has, thus  the  exit
       status 2 is not used by xzdec.

NOTES
       Use  xz(1)  instead of xzdec or lzmadec for normal everyday use.	 xzdec
       or lzmadec are meant only for situations where it is important to  have
       a smaller decompressor than the full-featured xz(1).

       xzdec  and  lzmadec are not really that small.  The size can be reduced
       further by dropping features from liblzma at  compile  time,  but  that
       shouldn't  usually  be done for executables distributed in typical non-
       embedded operating system distributions.	 If you need a truly small .xz
       decompressor, consider using XZ Embedded.

SEE ALSO
       xz(1)

       XZ Embedded: <https://tukaani.org/xz/embedded.html>



Tukaani				  2024-04-08			      XZDEC(1)

XZDEC(1)			   XZ Utils			      XZDEC(1)



NAME
       xzdec, lzmadec - Small .xz and .lzma decompressors

SYNOPSIS
       xzdec [option...]  [file...]
       lzmadec [option...]  [file...]

DESCRIPTION
       xzdec is a liblzma-based decompression-only tool for .xz (and only .xz)
       files.  xzdec is intended to work as a drop-in replacement for xz(1) in
       the  most  common  situations where a script has been written to use xz
       --decompress --stdout (and possibly a few other commonly used  options)
       to decompress .xz files.	 lzmadec is identical to xzdec except that lz‐
       madec supports .lzma files instead of .xz files.

       To reduce the size of the  executable,  xzdec  doesn't  support	multi‐
       threading  or  localization,  and doesn't read options from XZ_DEFAULTS
       and XZ_OPT environment variables.  xzdec doesn't support displaying in‐
       termediate progress information: sending SIGINFO to xzdec does nothing,
       but sending  SIGUSR1  terminates	 the  process  instead	of  displaying
       progress information.

OPTIONS
       -d, --decompress, --uncompress
	      Ignored for xz(1) compatibility.	xzdec supports only decompres‐
	      sion.

       -k, --keep
	      Ignored for xz(1) compatibility.	xzdec never creates or removes
	      any files.

       -c, --stdout, --to-stdout
	      Ignored for xz(1) compatibility.	xzdec always writes the decom‐
	      pressed data to standard output.

       -q, --quiet
	      Specifying this once does nothing since xzdec never displays any
	      warnings or notices.  Specify this twice to suppress errors.

       -Q, --no-warn
	      Ignored for xz(1) compatibility.	xzdec never uses the exit sta‐
	      tus 2.

       -h, --help
	      Display a help message and exit successfully.

       -V, --version
	      Display the version number of xzdec and liblzma.

EXIT STATUS
       0      All was good.

       1      An error occurred.

       xzdec doesn't have any warning messages like xz(1) has, thus  the  exit
       status 2 is not used by xzdec.

NOTES
       Use  xz(1)  instead of xzdec or lzmadec for normal everyday use.	 xzdec
       or lzmadec are meant only for situations where it is important to  have
       a smaller decompressor than the full-featured xz(1).

       xzdec  and  lzmadec are not really that small.  The size can be reduced
       further by dropping features from liblzma at  compile  time,  but  that
       shouldn't  usually  be done for executables distributed in typical non-
       embedded operating system distributions.	 If you need a truly small .xz
       decompressor, consider using XZ Embedded.

SEE ALSO
       xz(1)

       XZ Embedded: <https://tukaani.org/xz/embedded.html>



Tukaani				  2024-04-08			      XZDEC(1)

XZ(1)				   XZ Utils				 XZ(1)



NAME
       xz,  unxz,  xzcat, lzma, unlzma, lzcat - Compress or decompress .xz and
       .lzma files

SYNOPSIS
       xz [option...]  [file...]

COMMAND ALIASES
       unxz is equivalent to xz --decompress.
       xzcat is equivalent to xz --decompress --stdout.
       lzma is equivalent to xz --format=lzma.
       unlzma is equivalent to xz --format=lzma --decompress.
       lzcat is equivalent to xz --format=lzma --decompress --stdout.

       When writing scripts that need to decompress files, it  is  recommended
       to  always use the name xz with appropriate arguments (xz -d or xz -dc)
       instead of the names unxz and xzcat.

DESCRIPTION
       xz is a general-purpose data compression tool with command line	syntax
       similar	to  gzip(1)  and  bzip2(1).  The native file format is the .xz
       format, but the legacy .lzma format used by LZMA	 Utils	and  raw  com‐
       pressed	streams	 with  no container format headers are also supported.
       In addition, decompression of the .lz format used by lzip is supported.

       xz compresses or decompresses each file according to the selected oper‐
       ation mode.  If no files are given or file is -, xz reads from standard
       input and writes the processed data to standard output.	xz will refuse
       (display	 an error and skip the file) to write compressed data to stan‐
       dard output if it is a terminal.	 Similarly, xz	will  refuse  to  read
       compressed data from standard input if it is a terminal.

       Unless  --stdout	 is specified, files other than - are written to a new
       file whose name is derived from the source file name:

       •  When compressing, the suffix of  the	target	file  format  (.xz  or
	  .lzma)  is  appended	to the source filename to get the target file‐
	  name.

       •  When decompressing, the .xz, .lzma, or .lz suffix  is	 removed  from
	  the  filename	 to  get  the target filename.	xz also recognizes the
	  suffixes .txz and .tlz, and replaces them with the .tar suffix.

       If the target file already exists, an error is displayed and  the  file
       is skipped.

       Unless  writing	to standard output, xz will display a warning and skip
       the file if any of the following applies:

       •  File is not a regular file.  Symbolic links are  not	followed,  and
	  thus they are not considered to be regular files.

       •  File has more than one hard link.

       •  File has setuid, setgid, or sticky bit set.

       •  The  operation  mode	is  set to compress and the file already has a
	  suffix of the target file format (.xz or .txz	 when  compressing  to
	  the .xz format, and .lzma or .tlz when compressing to the .lzma for‐
	  mat).

       •  The operation mode is set to decompress and the file doesn't have  a
	  suffix of any of the supported file formats (.xz, .txz, .lzma, .tlz,
	  or .lz).

       After successfully compressing or decompressing the file, xz copies the
       owner,  group, permissions, access time, and modification time from the
       source file to the target file.	If copying the group fails,  the  per‐
       missions are modified so that the target file doesn't become accessible
       to users who didn't have permission to  access  the  source  file.   xz
       doesn't support copying other metadata like access control lists or ex‐
       tended attributes yet.

       Once the target file has been successfully closed, the source  file  is
       removed	unless --keep was specified.  The source file is never removed
       if the output is written to standard output or if an error occurs.

       Sending SIGINFO or SIGUSR1 to the xz process makes  it  print  progress
       information  to	standard  error.  This has only limited use since when
       standard error is a terminal, using --verbose will display an automati‐
       cally updating progress indicator.

   Memory usage
       The  memory  usage of xz varies from a few hundred kilobytes to several
       gigabytes depending on the compression  settings.   The	settings  used
       when compressing a file determine the memory requirements of the decom‐
       pressor.	 Typically the decompressor needs 5 % to 20 % of the amount of
       memory that the compressor needed when creating the file.  For example,
       decompressing a file created with xz -9 currently  requires  65 MiB  of
       memory.	 Still,	 it is possible to have .xz files that require several
       gigabytes of memory to decompress.

       Especially users of older systems may  find  the	 possibility  of  very
       large  memory  usage  annoying.	To prevent uncomfortable surprises, xz
       has a built-in memory usage limiter,  which  is	disabled  by  default.
       While  some operating systems provide ways to limit the memory usage of
       processes, relying on it wasn't deemed to be flexible enough (for exam‐
       ple, using ulimit(1) to limit virtual memory tends to cripple mmap(2)).

       The  memory  usage  limiter can be enabled with the command line option
       --memlimit=limit.  Often it is more convenient to enable the limiter by
       default	by  setting the environment variable XZ_DEFAULTS, for example,
       XZ_DEFAULTS=--memlimit=150MiB.  It is possible to set the limits	 sepa‐
       rately  for  compression	 and  decompression  by	 using --memlimit-com‐
       press=limit and --memlimit-decompress=limit.  Using these  two  options
       outside	XZ_DEFAULTS is rarely useful because a single run of xz cannot
       do both compression  and	 decompression	and  --memlimit=limit  (or  -M
       limit) is shorter to type on the command line.

       If  the specified memory usage limit is exceeded when decompressing, xz
       will display an error and decompressing the file	 will  fail.   If  the
       limit  is  exceeded when compressing, xz will try to scale the settings
       down so that the limit is no longer exceeded (except when using	--for‐
       mat=raw	or --no-adjust).  This way the operation won't fail unless the
       limit is very small.  The scaling of the settings is done in steps that
       don't match the compression level presets, for example, if the limit is
       only slightly less than the amount required for	xz  -9,	 the  settings
       will be scaled down only a little, not all the way down to xz -8.

   Concatenation and padding with .xz files
       It is possible to concatenate .xz files as is.  xz will decompress such
       files as if they were a single .xz file.

       It is possible to insert padding between the concatenated parts or  af‐
       ter the last part.  The padding must consist of null bytes and the size
       of the padding must be a multiple of four bytes.	 This can  be  useful,
       for  example,  if the .xz file is stored on a medium that measures file
       sizes in 512-byte blocks.

       Concatenation and padding are not  allowed  with	 .lzma	files  or  raw
       streams.

OPTIONS
   Integer suffixes and special values
       In  most places where an integer argument is expected, an optional suf‐
       fix is supported to easily indicate large integers.  There must	be  no
       space between the integer and the suffix.

       KiB    Multiply	the integer by 1,024 (2^10).  Ki, k, kB, K, and KB are
	      accepted as synonyms for KiB.

       MiB    Multiply the integer by 1,048,576 (2^20).	 Mi, m, M, and MB  are
	      accepted as synonyms for MiB.

       GiB    Multiply	the integer by 1,073,741,824 (2^30).  Gi, g, G, and GB
	      are accepted as synonyms for GiB.

       The special value max can be used to indicate the maximum integer value
       supported by the option.

   Operation mode
       If  multiple  operation	mode options are given, the last one takes ef‐
       fect.

       -z, --compress
	      Compress.	 This is the default operation mode when no  operation
	      mode  option is specified and no other operation mode is implied
	      from the command name (for example, unxz implies --decompress).

	      After successful compression, the source file is removed	unless
	      writing to standard output or --keep was specified.

       -d, --decompress, --uncompress
	      Decompress.   After successful decompression, the source file is
	      removed unless writing to standard output or --keep  was	speci‐
	      fied.

       -t, --test
	      Test  the integrity of compressed files.	This option is equiva‐
	      lent to --decompress --stdout except that the decompressed  data
	      is  discarded  instead  of being written to standard output.  No
	      files are created or removed.

       -l, --list
	      Print information about compressed files.	 No uncompressed  out‐
	      put  is  produced, and no files are created or removed.  In list
	      mode, the program cannot read the compressed data from  standard
	      input or from other unseekable sources.

	      The  default  listing  shows  basic information about files, one
	      file per line.  To get more detailed information, use  also  the
	      --verbose	 option.   For	even  more  information, use --verbose
	      twice, but note that this may be slow, because getting  all  the
	      extra  information  requires  many  seeks.  The width of verbose
	      output exceeds 80 characters, so piping the output to, for exam‐
	      ple,  less -S  may  be  convenient  if  the  terminal isn't wide
	      enough.

	      The exact output may vary between xz versions and different  lo‐
	      cales.   For  machine-readable  output, --robot --list should be
	      used.

   Operation modifiers
       -k, --keep
	      Don't delete the input files.

	      Since xz 5.2.6, this option also makes xz compress or decompress
	      even if the input is a symbolic link to a regular file, has more
	      than one hard link, or has the setuid,  setgid,  or  sticky  bit
	      set.   The setuid, setgid, and sticky bits are not copied to the
	      target file.  In	earlier	 versions  this	 was  only  done  with
	      --force.

       -f, --force
	      This option has several effects:

	      •	 If the target file already exists, delete it before compress‐
		 ing or decompressing.

	      •	 Compress or decompress even if the input is a	symbolic  link
		 to  a	regular	 file, has more than one hard link, or has the
		 setuid, setgid, or sticky bit set.  The setuid,  setgid,  and
		 sticky bits are not copied to the target file.

	      •	 When  used with --decompress --stdout and xz cannot recognize
		 the type of the source file, copy the source file  as	is  to
		 standard  output.   This allows xzcat --force to be used like
		 cat(1) for files that have not been compressed with xz.  Note
		 that in future, xz might support new compressed file formats,
		 which may make xz decompress more types of files  instead  of
		 copying  them	as is to standard output.  --format=format can
		 be used to restrict xz to decompress only a single file  for‐
		 mat.

       -c, --stdout, --to-stdout
	      Write the compressed or decompressed data to standard output in‐
	      stead of a file.	This implies --keep.

       --single-stream
	      Decompress only the first .xz stream, and silently ignore possi‐
	      ble  remaining  input  data following the stream.	 Normally such
	      trailing garbage makes xz display an error.

	      xz never decompresses more than one stream from .lzma  files  or
	      raw  streams, but this option still makes xz ignore the possible
	      trailing data after the .lzma file or raw stream.

	      This option has no effect if the operation mode is not  --decom‐
	      press or --test.

       --no-sparse
	      Disable  creation of sparse files.  By default, if decompressing
	      into a regular file, xz tries to make the file sparse if the de‐
	      compressed  data	contains  long	sequences of binary zeros.  It
	      also works when writing to standard output as long  as  standard
	      output  is  connected  to	 a regular file and certain additional
	      conditions are met to make it safe.  Creating sparse  files  may
	      save  disk  space and speed up the decompression by reducing the
	      amount of disk I/O.

       -S .suf, --suffix=.suf
	      When compressing, use .suf as the suffix for the target file in‐
	      stead  of	 .xz  or .lzma.	 If not writing to standard output and
	      the source file already has the suffix .suf, a warning  is  dis‐
	      played and the file is skipped.

	      When  decompressing, recognize files with the suffix .suf in ad‐
	      dition to files with the .xz, .txz, .lzma, .tlz, or .lz  suffix.
	      If the source file has the suffix .suf, the suffix is removed to
	      get the target filename.

	      When compressing or decompressing	 raw  streams  (--format=raw),
	      the  suffix  must always be specified unless writing to standard
	      output, because there is no default suffix for raw streams.

       --files[=file]
	      Read the filenames to process from file;	if  file  is  omitted,
	      filenames	 are read from standard input.	Filenames must be ter‐
	      minated with the newline character.  A dash (-) is  taken	 as  a
	      regular  filename; it doesn't mean standard input.  If filenames
	      are given also as command line arguments, they are processed be‐
	      fore the filenames read from file.

       --files0[=file]
	      This  is	identical  to --files[=file] except that each filename
	      must be terminated with the null character.

   Basic file format and compression options
       -F format, --format=format
	      Specify the file format to compress or decompress:

	      auto   This is the default.  When compressing, auto  is  equiva‐
		     lent  to xz.  When decompressing, the format of the input
		     file is automatically detected.  Note  that  raw  streams
		     (created with --format=raw) cannot be auto-detected.

	      xz     Compress to the .xz file format, or accept only .xz files
		     when decompressing.

	      lzma, alone
		     Compress to the legacy .lzma file format, or accept  only
		     .lzma  files  when	 decompressing.	  The alternative name
		     alone is provided for backwards compatibility  with  LZMA
		     Utils.

	      lzip   Accept only .lz files when decompressing.	Compression is
		     not supported.

		     The .lz format version 0 and the unextended version 1 are
		     supported.	 Version 0 files were produced by lzip 1.3 and
		     older.  Such files aren't common but may  be  found  from
		     file  archives  as a few source packages were released in
		     this format.  People might have  old  personal  files  in
		     this  format  too.	  Decompression support for the format
		     version 0 was removed in lzip 1.18.

		     lzip 1.4 and later create files in the format version  1.
		     The  sync	flush marker extension to the format version 1
		     was added in lzip 1.6.  This extension is rarely used and
		     isn't supported by xz (diagnosed as corrupt input).

	      raw    Compress  or  uncompress a raw stream (no headers).  This
		     is meant for advanced users only.	To decode raw streams,
		     you need use --format=raw and explicitly specify the fil‐
		     ter chain, which normally would have been stored  in  the
		     container headers.

       -C check, --check=check
	      Specify  the  type  of the integrity check.  The check is calcu‐
	      lated from the uncompressed data and stored  in  the  .xz	 file.
	      This  option  has	 an  effect only when compressing into the .xz
	      format; the .lzma format doesn't support integrity checks.   The
	      integrity check (if any) is verified when the .xz file is decom‐
	      pressed.

	      Supported check types:

	      none   Don't calculate an integrity check at all.	 This is  usu‐
		     ally  a  bad  idea.  This can be useful when integrity of
		     the data is verified by other means anyway.

	      crc32  Calculate CRC32  using  the  polynomial  from  IEEE-802.3
		     (Ethernet).

	      crc64  Calculate CRC64 using the polynomial from ECMA-182.  This
		     is the default, since it is slightly better than CRC32 at
		     detecting	damaged files and the speed difference is neg‐
		     ligible.

	      sha256 Calculate SHA-256.	 This is somewhat  slower  than	 CRC32
		     and CRC64.

	      Integrity	 of the .xz headers is always verified with CRC32.  It
	      is not possible to change or disable it.

       --ignore-check
	      Don't verify the integrity check of the compressed data when de‐
	      compressing.   The CRC32 values in the .xz headers will still be
	      verified normally.

	      Do not use this option unless you know what you are doing.  Pos‐
	      sible reasons to use this option:

	      •	 Trying to recover data from a corrupt .xz file.

	      •	 Speeding  up decompression.  This matters mostly with SHA-256
		 or with files that have compressed extremely well.  It's rec‐
		 ommended  to  not use this option for this purpose unless the
		 file integrity is verified externally in some other way.

       -0 ... -9
	      Select a compression preset level.  The default is -6.  If  mul‐
	      tiple  preset  levels  are specified, the last one takes effect.
	      If a custom filter chain was already specified, setting  a  com‐
	      pression preset level clears the custom filter chain.

	      The  differences	between	 the presets are more significant than
	      with gzip(1) and bzip2(1).  The  selected	 compression  settings
	      determine	 the memory requirements of the decompressor, thus us‐
	      ing a too high preset level might make it painful to  decompress
	      the  file	 on an old system with little RAM.  Specifically, it's
	      not a good idea to blindly use -9 for everything like  it	 often
	      is with gzip(1) and bzip2(1).

	      -0 ... -3
		     These  are somewhat fast presets.	-0 is sometimes faster
		     than gzip -9 while compressing much better.   The	higher
		     ones  often have speed comparable to bzip2(1) with compa‐
		     rable or better compression ratio, although  the  results
		     depend a lot on the type of data being compressed.

	      -4 ... -6
		     Good  to very good compression while keeping decompressor
		     memory usage reasonable even for old systems.  -6 is  the
		     default,  which is usually a good choice for distributing
		     files that need to be decompressible even on systems with
		     only  16 MiB  RAM.	  (-5e or -6e may be worth considering
		     too.  See --extreme.)

	      -7 ... -9
		     These are like -6 but with higher compressor  and	decom‐
		     pressor  memory requirements.  These are useful only when
		     compressing files bigger than 8 MiB, 16 MiB, and  32 MiB,
		     respectively.

	      On the same hardware, the decompression speed is approximately a
	      constant number of bytes of  compressed  data  per  second.   In
	      other  words,  the better the compression, the faster the decom‐
	      pression will usually be.	 This also means that  the  amount  of
	      uncompressed output produced per second can vary a lot.

	      The following table summarises the features of the presets:

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem -0;256 KiB;0;3 MiB;1 MiB -1;1 MiB;1;9
		     MiB;2 MiB -2;2 MiB;2;17 MiB;3 MiB -3;4 MiB;3;32 MiB;5 MiB
		     -4;4 MiB;4;48 MiB;5 MiB  -5;8  MiB;5;94  MiB;9  MiB  -6;8
		     MiB;6;94  MiB;9  MiB  -7;16  MiB;6;186  MiB;17  MiB -8;32
		     MiB;6;370 MiB;33 MiB -9;64 MiB;6;674 MiB;65 MiB

	      Column descriptions:

	      •	 DictSize is the LZMA2 dictionary size.	 It is waste of memory
		 to  use a dictionary bigger than the size of the uncompressed
		 file.	This is why it is good to avoid using the  presets  -7
		 ...  -9 when there's no real need for them.  At -6 and lower,
		 the amount of memory wasted is usually low enough to not mat‐
		 ter.

	      •	 CompCPU  is a simplified representation of the LZMA2 settings
		 that affect compression speed.	 The dictionary	 size  affects
		 speed too, so while CompCPU is the same for levels -6 ... -9,
		 higher levels still tend to be a little slower.  To get  even
		 slower and thus possibly better compression, see --extreme.

	      •	 CompMem  contains  the	 compressor memory requirements in the
		 single-threaded mode.	It may vary slightly between  xz  ver‐
		 sions.

	      •	 DecMem	 contains  the decompressor memory requirements.  That
		 is, the compression settings determine	 the  memory  require‐
		 ments of the decompressor.  The exact decompressor memory us‐
		 age is slightly more than the LZMA2 dictionary size, but  the
		 values	 in  the  table	 have been rounded up to the next full
		 MiB.

	      Memory requirements of the multi-threaded mode are significantly
	      higher  than that of the single-threaded mode.  With the default
	      value of --block-size, each thread needs 3*3*DictSize plus Comp‐
	      Mem  or  DecMem.	For example, four threads with preset -6 needs
	      660–670 MiB of memory.

       -e, --extreme
	      Use a slower variant of the selected  compression	 preset	 level
	      (-0 ... -9) to hopefully get a little bit better compression ra‐
	      tio, but with bad luck this can also make it worse.   Decompres‐
	      sor  memory  usage  is not affected, but compressor memory usage
	      increases a little at preset levels -0 ... -3.

	      Since there are two presets  with	 dictionary  sizes  4 MiB  and
	      8 MiB,  the  presets  -3e	 and  -5e use slightly faster settings
	      (lower CompCPU) than -4e and -6e, respectively.  That way no two
	      presets are identical.

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem  -0e;256  KiB;8;4  MiB;1  MiB	 -1e;1
		     MiB;8;13	MiB;2  MiB  -2e;2  MiB;8;25  MiB;3  MiB	 -3e;4
		     MiB;7;48  MiB;5  MiB  -4e;4  MiB;8;48  MiB;5  MiB	 -5e;8
		     MiB;7;94  MiB;9  MiB  -6e;8  MiB;8;94  MiB;9  MiB	-7e;16
		     MiB;8;186 MiB;17 MiB -8e;32 MiB;8;370 MiB;33  MiB	-9e;64
		     MiB;8;674 MiB;65 MiB

	      For  example,  there  are a total of four presets that use 8 MiB
	      dictionary, whose order from the fastest to the slowest  is  -5,
	      -6, -5e, and -6e.

       --fast
       --best These  are  somewhat  misleading	aliases for -0 and -9, respec‐
	      tively.  These are provided  only	 for  backwards	 compatibility
	      with LZMA Utils.	Avoid using these options.

       --block-size=size
	      When  compressing	 to  the .xz format, split the input data into
	      blocks of size bytes.  The blocks are  compressed	 independently
	      from each other, which helps with multi-threading and makes lim‐
	      ited random-access decompression possible.  This option is typi‐
	      cally  used to override the default block size in multi-threaded
	      mode, but this option can be used in single-threaded mode too.

	      In multi-threaded mode about three times size bytes will be  al‐
	      located  in each thread for buffering input and output.  The de‐
	      fault size is three times the LZMA2 dictionary size  or  1  MiB,
	      whichever is more.  Typically a good value is 2–4 times the size
	      of the LZMA2 dictionary or at least 1 MiB.  Using size less than
	      the LZMA2 dictionary size is waste of RAM because then the LZMA2
	      dictionary buffer will never get fully used.  In	multi-threaded
	      mode,  the  sizes of the blocks are stored in the block headers.
	      This size information is required for multi-threaded  decompres‐
	      sion.

	      In  single-threaded  mode no block splitting is done by default.
	      Setting this option doesn't affect memory usage.	No size infor‐
	      mation is stored in block headers, thus files created in single-
	      threaded mode won't be identical	to  files  created  in	multi-
	      threaded	mode.  The lack of size information also means that xz
	      won't be able decompress the files in multi-threaded mode.

       --block-list=items
	      When compressing to the .xz format, start a new  block  with  an
	      optional custom filter chain after the given intervals of uncom‐
	      pressed data.

	      The items are a comma-separated list.  Each item consists of  an
	      optional filter chain number between 0 and 9 followed by a colon
	      (:) and a required size of uncompressed data.  Omitting an  item
	      (two  or more consecutive commas) is a shorthand to use the size
	      and filters of the previous item.

	      If the input file is bigger than the sum of the sizes in	items,
	      the  last item is repeated until the end of the file.  A special
	      value of 0 may be used as the last size  to  indicate  that  the
	      rest of the file should be encoded as a single block.

	      An  alternative  filter chain for each block can be specified in
	      combination with the --filters1=filters  ...  --filters9=filters
	      options.	 These options define filter chains with an identifier
	      between 1–9.  Filter chain 0 can be used to refer to the default
	      filter  chain,  which  is	 the  same  as not specifying a filter
	      chain.  The filter chain identifier can be used before  the  un‐
	      compressed  size,	 followed by a colon (:).  For example, if one
	      specifies	 --block-list=1:2MiB,3:2MiB,2:4MiB,,2MiB,0:4MiB	  then
	      blocks will be created using:

	      •	 The filter chain specified by --filters1 and 2 MiB input

	      •	 The filter chain specified by --filters3 and 2 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The default filter chain and 2 MiB input

	      •	 The  default filter chain and 4 MiB input for every block un‐
		 til end of input.

	      If one specifies a size that exceeds the	encoder's  block  size
	      (either  the  default value in threaded mode or the value speci‐
	      fied with --block-size=size), the encoder will create additional
	      blocks while keeping the boundaries specified in items.  For ex‐
	      ample,	  if	  one	    specifies	    --block-size=10MiB
	      --block-list=5MiB,10MiB,8MiB,12MiB,24MiB	and  the input file is
	      80 MiB, one will get 11 blocks: 5, 10, 8, 10, 2, 10, 10, 4,  10,
	      10, and 1 MiB.

	      In multi-threaded mode the sizes of the blocks are stored in the
	      block headers.  This isn't done in single-threaded mode, so  the
	      encoded  output won't be identical to that of the multi-threaded
	      mode.

       --flush-timeout=timeout
	      When compressing, if more than timeout milliseconds (a  positive
	      integer)	has  passed  since the previous flush and reading more
	      input would block, all the pending input data  is	 flushed  from
	      the  encoder  and made available in the output stream.  This can
	      be useful if xz is used to compress data that is streamed over a
	      network.	 Small	timeout	 values make the data available at the
	      receiving end with a small delay, but large timeout values  give
	      better compression ratio.

	      This  feature  is disabled by default.  If this option is speci‐
	      fied more than once, the last one	 takes	effect.	  The  special
	      timeout  value  of 0 can be used to explicitly disable this fea‐
	      ture.

	      This feature is not available on non-POSIX systems.

	      This feature is still experimental.  Currently xz is  unsuitable
	      for  decompressing  the  stream  in real time due to how xz does
	      buffering.

       --memlimit-compress=limit
	      Set a memory usage limit for compression.	  If  this  option  is
	      specified multiple times, the last one takes effect.

	      If the compression settings exceed the limit, xz will attempt to
	      adjust the settings downwards so that the limit is no longer ex‐
	      ceeded  and display a notice that automatic adjustment was done.
	      The adjustments are done in this order: reducing the  number  of
	      threads, switching to single-threaded mode if even one thread in
	      multi-threaded mode exceeds the limit, and finally reducing  the
	      LZMA2 dictionary size.

	      When  compressing	 with  --format=raw or if --no-adjust has been
	      specified, only the number of threads may be  reduced  since  it
	      can be done without affecting the compressed output.

	      If  the  limit cannot be met even with the adjustments described
	      above, an error is displayed and xz will exit with  exit	status
	      1.

	      The limit can be specified in multiple ways:

	      •	 The  limit can be an absolute value in bytes.	Using an inte‐
		 ger suffix like MiB can be useful.  Example:  --memlimit-com‐
		 press=80MiB

	      •	 The  limit can be specified as a percentage of total physical
		 memory (RAM).	This can be useful especially when setting the
		 XZ_DEFAULTS  environment  variable  in a shell initialization
		 script that is shared between different computers.  That  way
		 the  limit  is automatically bigger on systems with more mem‐
		 ory.  Example: --memlimit-compress=70%

	      •	 The limit can be reset back to its default value  by  setting
		 it  to	 0.  This is currently equivalent to setting the limit
		 to max (no memory usage limit).

	      For 32-bit xz there is a special case: if	 the  limit  would  be
	      over 4020 MiB, the limit is set to 4020 MiB.  On MIPS32 2000 MiB
	      is used instead.	(The values 0 and max aren't affected by this.
	      A similar feature doesn't exist for decompression.)  This can be
	      helpful when a 32-bit executable has  access  to	4 GiB  address
	      space  (2	 GiB on MIPS32) while hopefully doing no harm in other
	      situations.

	      See also the section Memory usage.

       --memlimit-decompress=limit
	      Set a memory usage limit for decompression.  This	 also  affects
	      the  --list  mode.  If the operation is not possible without ex‐
	      ceeding the limit, xz will display an  error  and	 decompressing
	      the  file will fail.  See --memlimit-compress=limit for possible
	      ways to specify the limit.

       --memlimit-mt-decompress=limit
	      Set a memory usage limit for multi-threaded decompression.  This
	      can  only	 affect the number of threads; this will never make xz
	      refuse to decompress a file.  If limit is too low to  allow  any
	      multi-threading,	the  limit  is ignored and xz will continue in
	      single-threaded mode.  Note that if  also	 --memlimit-decompress
	      is used, it will always apply to both single-threaded and multi-
	      threaded modes, and so the effective limit  for  multi-threading
	      will  never  be higher than the limit set with --memlimit-decom‐
	      press.

	      In contrast to the other	memory	usage  limit  options,	--mem‐
	      limit-mt-decompress=limit	 has  a system-specific default limit.
	      xz --info-memory can be used to see the current value.

	      This option and its default  value  exist	 because  without  any
	      limit  the  threaded decompressor could end up allocating an in‐
	      sane amount of memory with some input  files.   If  the  default
	      limit is too low on your system, feel free to increase the limit
	      but never set it to a value larger than the amount of usable RAM
	      as  with	appropriate  input  files  xz will attempt to use that
	      amount of memory even with a low number of threads.  Running out
	      of  memory  or  swapping	will not improve decompression perfor‐
	      mance.

	      See --memlimit-compress=limit for possible ways to  specify  the
	      limit.   Setting limit to 0 resets the limit to the default sys‐
	      tem-specific value.

       -M limit, --memlimit=limit, --memory=limit
	      This  is	equivalent  to	specifying   --memlimit-compress=limit
	      --memlimit-decompress=limit --memlimit-mt-decompress=limit.

       --no-adjust
	      Display  an  error  and exit if the memory usage limit cannot be
	      met without adjusting settings that affect the  compressed  out‐
	      put.   That is, this prevents xz from switching the encoder from
	      multi-threaded mode to single-threaded mode  and	from  reducing
	      the  LZMA2  dictionary  size.  Even when this option is used the
	      number of threads may be reduced to meet the memory usage	 limit
	      as that won't affect the compressed output.

	      Automatic adjusting is always disabled when creating raw streams
	      (--format=raw).

       -T threads, --threads=threads
	      Specify the number of worker threads to use.  Setting threads to
	      a special value 0 makes xz use up to as many threads as the pro‐
	      cessor(s) on the system support.	The actual number  of  threads
	      can  be  fewer  than threads if the input file is not big enough
	      for threading with the given settings or if using	 more  threads
	      would exceed the memory usage limit.

	      The  single-threaded and multi-threaded compressors produce dif‐
	      ferent output.  Single-threaded compressor will give the	small‐
	      est  file	 size but only the output from the multi-threaded com‐
	      pressor can be decompressed  using  multiple  threads.   Setting
	      threads to 1 will use the single-threaded mode.  Setting threads
	      to any other value, including 0,	will  use  the	multi-threaded
	      compressor even if the system supports only one hardware thread.
	      (xz 5.2.x used single-threaded mode in this situation.)

	      To use multi-threaded mode with only one thread, set threads  to
	      +1.   The	 +  prefix  has no effect with values other than 1.  A
	      memory usage limit can still make xz switch  to  single-threaded
	      mode  unless  --no-adjust is used.  Support for the + prefix was
	      added in xz 5.4.0.

	      If an automatic number of threads has been requested and no mem‐
	      ory  usage  limit has been specified, then a system-specific de‐
	      fault soft limit will be used to possibly limit  the  number  of
	      threads.	 It is a soft limit in sense that it is ignored if the
	      number of threads becomes one, thus a soft limit will never stop
	      xz  from	compressing or decompressing.  This default soft limit
	      will not make xz switch  from  multi-threaded  mode  to  single-
	      threaded	 mode.	  The  active  limits  can  be	seen  with  xz
	      --info-memory.

	      Currently the only threading method is to split the  input  into
	      blocks and compress them independently from each other.  The de‐
	      fault block size depends on the compression  level  and  can  be
	      overridden with the --block-size=size option.

	      Threaded decompression only works on files that contain multiple
	      blocks with size information in block headers.  All large enough
	      files compressed in multi-threaded mode meet this condition, but
	      files  compressed	 in  single-threaded  mode   don't   even   if
	      --block-size=size has been used.

	      The  default  value for threads is 0.  In xz 5.4.x and older the
	      default is 1.

   Custom compressor filter chains
       A custom filter chain allows specifying the compression settings in de‐
       tail  instead  of  relying  on  the settings associated to the presets.
       When a custom filter chain is specified, preset options (-0 ... -9  and
       --extreme)  earlier on the command line are forgotten.  If a preset op‐
       tion is specified after one or more custom filter  chain	 options,  the
       new  preset  takes effect and the custom filter chain options specified
       earlier are forgotten.

       A filter chain is comparable to piping on the command line.  When  com‐
       pressing, the uncompressed input goes to the first filter, whose output
       goes to the next filter (if any).  The output of the last  filter  gets
       written	to  the compressed file.  The maximum number of filters in the
       chain is four, but typically a filter chain has only one	 or  two  fil‐
       ters.

       Many filters have limitations on where they can be in the filter chain:
       some filters can work only as the last filter in the chain,  some  only
       as  a non-last filter, and some work in any position in the chain.  De‐
       pending on the filter, this limitation is either inherent to the filter
       design or exists to prevent security issues.

       A  custom filter chain can be specified in two different ways.  The op‐
       tions --filters=filters and --filters1=filters  ...  --filters9=filters
       allow specifying an entire filter chain in one option using the liblzma
       filter string syntax.  Alternatively, a filter chain can	 be  specified
       by  using  one  or more individual filter options in the order they are
       wanted in the filter chain.  That is, the order of the individual  fil‐
       ter  options is significant!  When decoding raw streams (--format=raw),
       the filter chain must be specified in the same order as it  was	speci‐
       fied  when compressing.	Any individual filter or preset options speci‐
       fied before the full chain option (--filters=filters) will  be  forgot‐
       ten.  Individual filters specified after the full chain option will re‐
       set the filter chain.

       Both the full and individual filter options  take  filter-specific  op‐
       tions  as a comma-separated list.  Extra commas in options are ignored.
       Every option has a default value, so specify those you want to change.

       To see the whole filter chain and options, use xz  -vv  (that  is,  use
       --verbose twice).  This works also for viewing the filter chain options
       used by presets.

       --filters=filters
	      Specify the full filter chain or a preset in  a  single  option.
	      Each filter can be separated by spaces or two dashes (--).  fil‐
	      ters may need to be quoted on the shell command line  so	it  is
	      parsed  as  a  single option.  To denote options, use : or =.  A
	      preset can be prefixed with a - and followed with zero  or  more
	      flags.   The  only supported flag is e to apply the same options
	      as --extreme.

       --filters1=filters ... --filters9=filters
	      Specify up to nine additional filter chains  that	 can  be  used
	      with --block-list.

	      For  example,  when compressing an archive with executable files
	      followed by text files, the executable part could use  a	filter
	      chain with a BCJ filter and the text part only the LZMA2 filter.

       --filters-help
	      Display  a  help	message	 describing how to specify presets and
	      custom filter chains in the --filters and --filters1=filters ...
	      --filters9=filters options, and exit successfully.

       --lzma1[=options]
       --lzma2[=options]
	      Add  LZMA1  or  LZMA2 filter to the filter chain.	 These filters
	      can be used only as the last filter in the chain.

	      LZMA1 is a legacy filter, which is supported almost  solely  due
	      to  the  legacy  .lzma  file  format, which supports only LZMA1.
	      LZMA2 is an updated version of LZMA1 to fix some	practical  is‐
	      sues  of	LZMA1.	 The .xz format uses LZMA2 and doesn't support
	      LZMA1 at all.  Compression speed and ratios of LZMA1  and	 LZMA2
	      are practically the same.

	      LZMA1 and LZMA2 share the same set of options:

	      preset=preset
		     Reset  all LZMA1 or LZMA2 options to preset.  Preset con‐
		     sist of an integer, which may be followed by  single-let‐
		     ter  preset  modifiers.   The integer can be from 0 to 9,
		     matching the command line options -0 ...  -9.   The  only
		     supported	modifier  is  currently e, which matches --ex‐
		     treme.  If no preset is specified, the default values  of
		     LZMA1 or LZMA2 options are taken from the preset 6.

	      dict=size
		     Dictionary (history buffer) size indicates how many bytes
		     of the recently processed uncompressed data  is  kept  in
		     memory.   The  algorithm tries to find repeating byte se‐
		     quences (matches) in the uncompressed data,  and  replace
		     them with references to the data currently in the dictio‐
		     nary.  The bigger	the  dictionary,  the  higher  is  the
		     chance to find a match.  Thus, increasing dictionary size
		     usually improves compression ratio, but a dictionary big‐
		     ger than the uncompressed file is waste of memory.

		     Typical  dictionary  size	is from 64 KiB to 64 MiB.  The
		     minimum is 4 KiB.	The maximum for	 compression  is  cur‐
		     rently 1.5 GiB (1536 MiB).	 The decompressor already sup‐
		     ports dictionaries up to one byte less than 4 GiB,	 which
		     is the maximum for the LZMA1 and LZMA2 stream formats.

		     Dictionary	 size and match finder (mf) together determine
		     the memory usage of the LZMA1 or LZMA2 encoder.  The same
		     (or bigger) dictionary size is required for decompressing
		     that was used when compressing, thus the memory usage  of
		     the  decoder  is  determined  by the dictionary size used
		     when compressing.	The .xz headers store  the  dictionary
		     size  either  as 2^n or 2^n + 2^(n-1), so these sizes are
		     somewhat preferred for compression.  Other sizes will get
		     rounded up when stored in the .xz headers.

	      lc=lc  Specify  the number of literal context bits.  The minimum
		     is 0 and the maximum is 4; the default is	3.   In	 addi‐
		     tion, the sum of lc and lp must not exceed 4.

		     All  bytes	 that cannot be encoded as matches are encoded
		     as literals.  That is, literals are  simply  8-bit	 bytes
		     that are encoded one at a time.

		     The  literal  coding makes an assumption that the highest
		     lc bits of the previous uncompressed byte correlate  with
		     the  next byte.  For example, in typical English text, an
		     upper-case letter is often followed by a lower-case  let‐
		     ter,  and	a lower-case letter is usually followed by an‐
		     other lower-case letter.  In the US-ASCII character  set,
		     the highest three bits are 010 for upper-case letters and
		     011 for lower-case letters.  When lc is at least  3,  the
		     literal coding can take advantage of this property in the
		     uncompressed data.

		     The default value (3) is usually good.  If you want maxi‐
		     mum compression, test lc=4.  Sometimes it helps a little,
		     and sometimes it makes compression worse.	If it makes it
		     worse, test lc=2 too.

	      lp=lp  Specify the number of literal position bits.  The minimum
		     is 0 and the maximum is 4; the default is 0.

		     Lp affects what kind of  alignment	 in  the  uncompressed
		     data is assumed when encoding literals.  See pb below for
		     more information about alignment.

	      pb=pb  Specify the number of position bits.  The	minimum	 is  0
		     and the maximum is 4; the default is 2.

		     Pb	 affects  what	kind  of alignment in the uncompressed
		     data is assumed in general.  The default means  four-byte
		     alignment (2^pb=2^2=4), which is often a good choice when
		     there's no better guess.

		     When the alignment is known, setting pb  accordingly  may
		     reduce  the  file	size a little.	For example, with text
		     files having one-byte  alignment  (US-ASCII,  ISO-8859-*,
		     UTF-8),  setting  pb=0  can improve compression slightly.
		     For UTF-16 text, pb=1 is a good choice.  If the alignment
		     is	 an  odd  number  like 3 bytes, pb=0 might be the best
		     choice.

		     Even though the assumed alignment can be adjusted with pb
		     and  lp,  LZMA1  and  LZMA2  still slightly favor 16-byte
		     alignment.	 It might be worth taking  into	 account  when
		     designing	file  formats that are likely to be often com‐
		     pressed with LZMA1 or LZMA2.

	      mf=mf  Match finder has a major effect on encoder speed,	memory
		     usage,  and  compression ratio.  Usually Hash Chain match
		     finders are faster than Binary Tree match	finders.   The
		     default  depends  on the preset: 0 uses hc3, 1–3 use hc4,
		     and the rest use bt4.

		     The following match finders are  supported.   The	memory
		     usage  formulas below are rough approximations, which are
		     closest to the reality when dict is a power of two.

		     hc3    Hash Chain with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 7.5 (if dict <= 16 MiB);
			    dict * 5.5 + 64 MiB (if dict > 16 MiB)

		     hc4    Hash Chain with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 7.5 (if dict <= 32 MiB);
			    dict * 6.5 (if dict > 32 MiB)

		     bt2    Binary Tree with 2-byte hashing
			    Minimum value for nice: 2
			    Memory usage: dict * 9.5

		     bt3    Binary Tree with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 11.5 (if dict <= 16 MiB);
			    dict * 9.5 + 64 MiB (if dict > 16 MiB)

		     bt4    Binary Tree with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 11.5 (if dict <= 32 MiB);
			    dict * 10.5 (if dict > 32 MiB)

	      mode=mode
		     Compression mode specifies the method to analyze the data
		     produced  by  the match finder.  Supported modes are fast
		     and normal.  The default is fast for presets 0–3 and nor‐
		     mal for presets 4–9.

		     Usually  fast  is	used with Hash Chain match finders and
		     normal with Binary Tree match finders.  This is also what
		     the presets do.

	      nice=nice
		     Specify  what  is	considered  to	be a nice length for a
		     match.  Once a match of at least nice bytes is found, the
		     algorithm stops looking for possibly better matches.

		     Nice can be 2–273 bytes.  Higher values tend to give bet‐
		     ter compression ratio at the expense of speed.   The  de‐
		     fault depends on the preset.

	      depth=depth
		     Specify  the  maximum  search  depth in the match finder.
		     The default is the special value of 0,  which  makes  the
		     compressor determine a reasonable depth from mf and nice.

		     Reasonable depth for Hash Chains is 4–100 and 16–1000 for
		     Binary Trees.  Using very high values for depth can  make
		     the  encoder  extremely slow with some files.  Avoid set‐
		     ting the depth over 1000 unless you are prepared  to  in‐
		     terrupt  the  compression	in  case  it is taking far too
		     long.

	      When decoding raw streams (--format=raw), LZMA2 needs  only  the
	      dictionary size.	LZMA1 needs also lc, lp, and pb.

       --x86[=options]
       --arm[=options]
       --armthumb[=options]
       --arm64[=options]
       --powerpc[=options]
       --ia64[=options]
       --sparc[=options]
       --riscv[=options]
	      Add  a branch/call/jump (BCJ) filter to the filter chain.	 These
	      filters can be used only as a  non-last  filter  in  the	filter
	      chain.

	      A	 BCJ filter converts relative addresses in the machine code to
	      their absolute counterparts.  This doesn't change	 the  size  of
	      the  data	 but  it increases redundancy, which can help LZMA2 to
	      produce 0–15 % smaller .xz file.	The BCJ filters are always re‐
	      versible,	 so  using a BCJ filter for wrong type of data doesn't
	      cause any data loss, although it may make the compression	 ratio
	      slightly	worse.	 The  BCJ filters are very fast and use an in‐
	      significant amount of memory.

	      These BCJ filters have known problems related to the compression
	      ratio:

	      •	 Some  types of files containing executable code (for example,
		 object files, static libraries,  and  Linux  kernel  modules)
		 have  the  addresses  in  the instructions filled with filler
		 values.  These BCJ filters will still do the address  conver‐
		 sion, which will make the compression worse with these files.

	      •	 If a BCJ filter is applied on an archive, it is possible that
		 it makes the compression ratio worse than  not	 using	a  BCJ
		 filter.   For example, if there are similar or even identical
		 executables then filtering will likely make  the  files  less
		 similar  and thus compression is worse.  The contents of non-
		 executable files in the same  archive	can  matter  too.   In
		 practice  one has to try with and without a BCJ filter to see
		 which is better in each situation.

	      Different instruction sets have different	 alignment:  the  exe‐
	      cutable  file must be aligned to a multiple of this value in the
	      input data to make the filter work.

		     tab(;); l n l l n l.  Filter;Alignment;Notes x86;1;32-bit
		     or	  64-bit  x86  ARM;4;  ARM-Thumb;2;  ARM64;4;4096-byte
		     alignment is best PowerPC;4;Big endian only IA-64;16;Ita‐
		     nium SPARC;4; RISC-V;2;

	      Since  the  BCJ-filtered	data is usually compressed with LZMA2,
	      the compression ratio may be improved slightly if the LZMA2  op‐
	      tions are set to match the alignment of the selected BCJ filter.
	      Examples:

	      •	 IA-64 filter has 16-byte alignment so pb=4,lp=4,lc=0 is  good
		 with LZMA2 (2^4=16).

	      •	 RISC-V	 code  has  2-byte  or	4-byte	alignment depending on
		 whether the file contains 16-bit compressed instructions (the
		 C   extension).    When   16-bit   instructions   are	 used,
		 pb=2,lp=1,lc=3 or pb=1,lp=1,lc=3 is good.   When  16-bit  in‐
		 structions aren't present, pb=2,lp=2,lc=2 is the best.	 read‐
		 elf -h can be used to check if "RVC" appears on  the  "Flags"
		 line.

	      •	 ARM64 is always 4-byte aligned so pb=2,lp=2,lc=2 is the best.

	      •	 The  x86  filter is an exception.  It's usually good to stick
		 to LZMA2's defaults (pb=2,lp=0,lc=3) when compressing x86 ex‐
		 ecutables.

	      All BCJ filters support the same options:

	      start=offset
		     Specify the start offset that is used when converting be‐
		     tween relative and absolute addresses.  The  offset  must
		     be a multiple of the alignment of the filter (see the ta‐
		     ble above).  The default is zero.	In practice,  the  de‐
		     fault is good; specifying a custom offset is almost never
		     useful.

       --delta[=options]
	      Add the Delta filter to the filter chain.	 The Delta filter  can
	      be only used as a non-last filter in the filter chain.

	      Currently	 only simple byte-wise delta calculation is supported.
	      It can be useful when  compressing,  for	example,  uncompressed
	      bitmap  images or uncompressed PCM audio.	 However, special pur‐
	      pose algorithms may give significantly better results than Delta
	      +	 LZMA2.	  This is true especially with audio, which compresses
	      faster and better, for example, with flac(1).

	      Supported options:

	      dist=distance
		     Specify the distance of the delta calculation  in	bytes.
		     distance must be 1–256.  The default is 1.

		     For example, with dist=2 and eight-byte input A1 B1 A2 B3
		     A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

   Other options
       -q, --quiet
	      Suppress warnings and notices.  Specify this twice  to  suppress
	      errors too.  This option has no effect on the exit status.  That
	      is, even if a warning was suppressed, the exit status  to	 indi‐
	      cate a warning is still used.

       -v, --verbose
	      Be  verbose.   If	 standard error is connected to a terminal, xz
	      will display a progress indicator.  Specifying  --verbose	 twice
	      will give even more verbose output.

	      The progress indicator shows the following information:

	      •	 Completion  percentage is shown if the size of the input file
		 is known.  That is, the percentage cannot be shown in pipes.

	      •	 Amount of compressed data produced (compressing) or  consumed
		 (decompressing).

	      •	 Amount	 of  uncompressed  data consumed (compressing) or pro‐
		 duced (decompressing).

	      •	 Compression ratio, which is calculated by dividing the amount
		 of  compressed	 data processed so far by the amount of uncom‐
		 pressed data processed so far.

	      •	 Compression or decompression speed.  This is measured as  the
		 amount	 of  uncompressed  data consumed (compression) or pro‐
		 duced (decompression) per second.  It is shown	 after	a  few
		 seconds have passed since xz started processing the file.

	      •	 Elapsed time in the format M:SS or H:MM:SS.

	      •	 Estimated  remaining  time is shown only when the size of the
		 input file is known and a  couple  of	seconds	 have  already
		 passed	 since	xz  started  processing the file.  The time is
		 shown in a less precise format which never  has  any  colons,
		 for example, 2 min 30 s.

	      When  standard  error  is not a terminal, --verbose will make xz
	      print the filename, compressed size, uncompressed size, compres‐
	      sion  ratio,  and	 possibly also the speed and elapsed time on a
	      single line to standard error after compressing or decompressing
	      the file.	 The speed and elapsed time are included only when the
	      operation took at least a few seconds.  If the operation	didn't
	      finish,  for example, due to user interruption, also the comple‐
	      tion percentage is printed if the size  of  the  input  file  is
	      known.

       -Q, --no-warn
	      Don't set the exit status to 2 even if a condition worth a warn‐
	      ing was detected.	 This  option  doesn't	affect	the  verbosity
	      level,  thus  both  --quiet and --no-warn have to be used to not
	      display warnings and to not alter the exit status.

       --robot
	      Print messages in a machine-parsable format.  This  is  intended
	      to  ease	writing	 frontends  that want to use xz instead of li‐
	      blzma, which may be the case with various scripts.   The	output
	      with  this  option  enabled  is meant to be stable across xz re‐
	      leases.  See the section ROBOT MODE for details.

       --info-memory
	      Display, in human-readable  format,  how	much  physical	memory
	      (RAM)  and  how  many processor threads xz thinks the system has
	      and the memory usage limits for compression  and	decompression,
	      and exit successfully.

       -h, --help
	      Display  a  help	message	 describing the most commonly used op‐
	      tions, and exit successfully.

       -H, --long-help
	      Display a help message describing all features of xz,  and  exit
	      successfully

       -V, --version
	      Display  the  version number of xz and liblzma in human readable
	      format.  To get machine-parsable output, specify --robot	before
	      --version.

ROBOT MODE
       The robot mode is activated with the --robot option.  It makes the out‐
       put of xz easier to parse by other programs.  Currently --robot is sup‐
       ported  only  together  with --list, --filters-help, --info-memory, and
       --version.  It will be supported for compression and  decompression  in
       the future.

   List mode
       xz --robot --list uses tab-separated output.  The first column of every
       line has a string that indicates the type of the information  found  on
       that line:

       name   This is always the first line when starting to list a file.  The
	      second column on the line is the filename.

       file   This line contains overall information about the .xz file.  This
	      line is always printed after the name line.

       stream This line type is used only when --verbose was specified.	 There
	      are as many stream lines as there are streams in the .xz file.

       block  This line type is used only when --verbose was specified.	 There
	      are  as  many  block  lines as there are blocks in the .xz file.
	      The block lines are shown after all the stream lines;  different
	      line types are not interleaved.

       summary
	      This  line type is used only when --verbose was specified twice.
	      This line is printed after all block lines.  Like the file line,
	      the  summary  line  contains  overall  information about the .xz
	      file.

       totals This line is always the very last line of the list  output.   It
	      shows the total counts and sizes.

       The columns of the file lines:
	      2.  Number of streams in the file
	      3.  Total number of blocks in the stream(s)
	      4.  Compressed size of the file
	      5.  Uncompressed size of the file
	      6.  Compression  ratio,  for  example,  0.123.  If ratio is over
		  9.999, three dashes (---) are displayed instead of  the  ra‐
		  tio.
	      7.  Comma-separated  list of integrity check names.  The follow‐
		  ing strings are used for the known check types: None, CRC32,
		  CRC64,  and  SHA-256.	 For unknown check types, Unknown-N is
		  used, where N is the Check ID as a decimal  number  (one  or
		  two digits).
	      8.  Total size of stream padding in the file

       The columns of the stream lines:
	      2.  Stream number (the first stream is 1)
	      3.  Number of blocks in the stream
	      4.  Compressed start offset
	      5.  Uncompressed start offset
	      6.  Compressed size (does not include stream padding)
	      7.  Uncompressed size
	      8.  Compression ratio
	      9.  Name of the integrity check
	      10. Size of stream padding

       The columns of the block lines:
	      2.  Number of the stream containing this block
	      3.  Block	 number	 relative  to the beginning of the stream (the
		  first block is 1)
	      4.  Block number relative to the beginning of the file
	      5.  Compressed start offset relative to  the  beginning  of  the
		  file
	      6.  Uncompressed	start  offset relative to the beginning of the
		  file
	      7.  Total compressed size of the block (includes headers)
	      8.  Uncompressed size
	      9.  Compression ratio
	      10. Name of the integrity check

       If --verbose was specified twice, additional columns  are  included  on
       the  block lines.  These are not displayed with a single --verbose, be‐
       cause getting this information requires many  seeks  and	 can  thus  be
       slow:
	      11. Value of the integrity check in hexadecimal
	      12. Block header size
	      13. Block	 flags:	 c  indicates that compressed size is present,
		  and u indicates that uncompressed size is present.   If  the
		  flag	is  not	 set,  a dash (-) is shown instead to keep the
		  string length fixed.	New flags may be added to the  end  of
		  the string in the future.
	      14. Size	of  the	 actual compressed data in the block (this ex‐
		  cludes the block header, block padding, and check fields)
	      15. Amount of memory (in	bytes)	required  to  decompress  this
		  block with this xz version
	      16. Filter  chain.   Note	 that most of the options used at com‐
		  pression time cannot be known, because only the options that
		  are needed for decompression are stored in the .xz headers.

       The columns of the summary lines:
	      2.  Amount of memory (in bytes) required to decompress this file
		  with this xz version
	      3.  yes or no indicating if all block  headers  have  both  com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      4.  Minimum xz version required to decompress the file

       The columns of the totals line:
	      2.  Number of streams
	      3.  Number of blocks
	      4.  Compressed size
	      5.  Uncompressed size
	      6.  Average compression ratio
	      7.  Comma-separated  list	 of  integrity	check  names that were
		  present in the files
	      8.  Stream padding size
	      9.  Number of files.  This is here to keep the order of the ear‐
		  lier columns the same as on file lines.

       If  --verbose  was  specified twice, additional columns are included on
       the totals line:
	      10. Maximum amount of memory (in bytes) required	to  decompress
		  the files with this xz version
	      11. yes  or  no  indicating  if all block headers have both com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      12. Minimum xz version required to decompress the file

       Future versions may add new line types and new columns can be added  to
       the existing line types, but the existing columns won't be changed.

   Filters help
       xz --robot --filters-help prints the supported filters in the following
       format:

       filter:option=<value>,option=<value>...

       filter Name of the filter

       option Name of a filter specific option

       value  Numeric value ranges appear as <min-max>.	 String value  choices
	      are shown within < > and separated by a | character.

       Each filter is printed on its own line.

   Memory limit information
       xz  --robot  --info-memory prints a single line with multiple tab-sepa‐
       rated columns:

       1.  Total amount of physical memory (RAM) in bytes.

       2.  Memory usage limit for compression in bytes	(--memlimit-compress).
	   A  special  value of 0 indicates the default setting which for sin‐
	   gle-threaded mode is the same as no limit.

       3.  Memory usage limit for decompression	 in  bytes  (--memlimit-decom‐
	   press).   A	special value of 0 indicates the default setting which
	   for single-threaded mode is the same as no limit.

       4.  Since xz 5.3.4alpha: Memory usage for multi-threaded	 decompression
	   in  bytes (--memlimit-mt-decompress).  This is never zero because a
	   system-specific default value shown in the column 5 is used	if  no
	   limit  has  been  specified explicitly.  This is also never greater
	   than the value in the column 3 even if  a  larger  value  has  been
	   specified with --memlimit-mt-decompress.

       5.  Since  xz  5.3.4alpha: A system-specific default memory usage limit
	   that is used to limit the number of threads when  compressing  with
	   an  automatic  number  of threads (--threads=0) and no memory usage
	   limit has been specified (--memlimit-compress).  This is also  used
	   as the default value for --memlimit-mt-decompress.

       6.  Since xz 5.3.4alpha: Number of available processor threads.

       In  the	future,	 the  output of xz --robot --info-memory may have more
       columns, but never more than a single line.

   Version
       xz --robot --version prints the version number of xz and liblzma in the
       following format:

       XZ_VERSION=XYYYZZZS
       LIBLZMA_VERSION=XYYYZZZS

       X      Major version.

       YYY    Minor  version.  Even numbers are stable.	 Odd numbers are alpha
	      or beta versions.

       ZZZ    Patch level for stable releases or just a counter	 for  develop‐
	      ment releases.

       S      Stability.  0 is alpha, 1 is beta, and 2 is stable.  S should be
	      always 2 when YYY is even.

       XYYYZZZS are the same on both lines if xz and liblzma are from the same
       XZ Utils release.

       Examples: 4.999.9beta is 49990091 and 5.0.0 is 50000002.

EXIT STATUS
       0      All is good.

       1      An error occurred.

       2      Something	 worth	a  warning  occurred, but no actual errors oc‐
	      curred.

       Notices (not warnings or errors) printed on standard error don't affect
       the exit status.

ENVIRONMENT
       xz  parses  space-separated lists of options from the environment vari‐
       ables XZ_DEFAULTS and XZ_OPT, in this order, before parsing the options
       from  the command line.	Note that only options are parsed from the en‐
       vironment variables; all non-options are silently ignored.  Parsing  is
       done  with getopt_long(3) which is used also for the command line argu‐
       ments.

       XZ_DEFAULTS
	      User-specific or system-wide default options.  Typically this is
	      set in a shell initialization script to enable xz's memory usage
	      limiter by default.  Excluding shell initialization scripts  and
	      similar  special	cases,	scripts must never set or unset XZ_DE‐
	      FAULTS.

       XZ_OPT This is for passing options to xz when it is not possible to set
	      the  options  directly on the xz command line.  This is the case
	      when xz is run by a script or tool, for example, GNU tar(1):

		     XZ_OPT=-2v tar caf foo.tar.xz foo

	      Scripts may use XZ_OPT, for example, to set script-specific  de‐
	      fault  compression  options.   It	 is still recommended to allow
	      users to override XZ_OPT if that is reasonable.  For example, in
	      sh(1) scripts one may use something like this:

		     XZ_OPT=${XZ_OPT-"-7e"}
		     export XZ_OPT

LZMA UTILS COMPATIBILITY
       The  command  line  syntax of xz is practically a superset of lzma, un‐
       lzma, and lzcat as found from LZMA Utils 4.32.x.	 In most cases, it  is
       possible	 to replace LZMA Utils with XZ Utils without breaking existing
       scripts.	 There are some incompatibilities though, which may  sometimes
       cause problems.

   Compression preset levels
       The  numbering  of the compression level presets is not identical in xz
       and LZMA Utils.	The most important difference is how dictionary	 sizes
       are  mapped  to different presets.  Dictionary size is roughly equal to
       the decompressor memory usage.

	      tab(;); c c c c n n.  Level;xz;LZMA Utils	 -0;256	 KiB;N/A  -1;1
	      MiB;64  KiB  -2;2 MiB;1 MiB -3;4 MiB;512 KiB -4;4 MiB;1 MiB -5;8
	      MiB;2 MiB -6;8 MiB;4 MiB -7;16 MiB;8 MiB -8;32 MiB;16 MiB	 -9;64
	      MiB;32 MiB

       The dictionary size differences affect the compressor memory usage too,
       but there are some other differences between LZMA Utils and  XZ	Utils,
       which make the difference even bigger:

	      tab(;);  c  c  c c n n.  Level;xz;LZMA Utils 4.32.x -0;3 MiB;N/A
	      -1;9 MiB;2 MiB -2;17 MiB;12 MiB -3;32 MiB;12  MiB	 -4;48	MiB;16
	      MiB  -5;94  MiB;26 MiB -6;94 MiB;45 MiB -7;186 MiB;83 MiB -8;370
	      MiB;159 MiB -9;674 MiB;311 MiB

       The default preset level in LZMA Utils is -7 while in XZ	 Utils	it  is
       -6, so both use an 8 MiB dictionary by default.

   Streamed vs. non-streamed .lzma files
       The  uncompressed  size	of the file can be stored in the .lzma header.
       LZMA Utils does that when compressing regular files.   The  alternative
       is  to  mark  that  uncompressed size is unknown and use end-of-payload
       marker to indicate where the decompressor should stop.  LZMA Utils uses
       this  method when uncompressed size isn't known, which is the case, for
       example, in pipes.

       xz supports decompressing .lzma files with  or  without	end-of-payload
       marker,	but  all  .lzma	 files	created	 by xz will use end-of-payload
       marker and have uncompressed  size  marked  as  unknown	in  the	 .lzma
       header.	 This may be a problem in some uncommon situations.  For exam‐
       ple, a .lzma decompressor in an embedded device might  work  only  with
       files  that have known uncompressed size.  If you hit this problem, you
       need to use LZMA Utils or LZMA SDK to create .lzma files with known un‐
       compressed size.

   Unsupported .lzma files
       The .lzma format allows lc values up to 8, and lp values up to 4.  LZMA
       Utils can decompress files with any lc and lp, but always creates files
       with  lc=3  and	lp=0.  Creating files with other lc and lp is possible
       with xz and with LZMA SDK.

       The implementation of the LZMA1 filter in liblzma requires that the sum
       of  lc  and lp must not exceed 4.  Thus, .lzma files, which exceed this
       limitation, cannot be decompressed with xz.

       LZMA Utils creates only .lzma files which have a dictionary size of 2^n
       (a power of 2) but accepts files with any dictionary size.  liblzma ac‐
       cepts only .lzma files which have a dictionary size of  2^n  or	2^n  +
       2^(n-1).	  This	is  to	decrease  false positives when detecting .lzma
       files.

       These limitations shouldn't be a problem in practice, since practically
       all  .lzma  files  have been compressed with settings that liblzma will
       accept.

   Trailing garbage
       When decompressing, LZMA Utils silently	ignore	everything  after  the
       first  .lzma  stream.   In  most	 situations, this is a bug.  This also
       means that LZMA Utils don't support  decompressing  concatenated	 .lzma
       files.

       If  there  is  data left after the first .lzma stream, xz considers the
       file to be corrupt unless --single-stream was used.  This may break ob‐
       scure scripts which have assumed that trailing garbage is ignored.

NOTES
   Compressed output may vary
       The  exact  compressed output produced from the same uncompressed input
       file may vary between XZ Utils versions even if compression options are
       identical.  This is because the encoder can be improved (faster or bet‐
       ter compression) without affecting the file  format.   The  output  can
       vary  even  between  different  builds of the same XZ Utils version, if
       different build options are used.

       The above means that once --rsyncable has been implemented, the result‐
       ing  files won't necessarily be rsyncable unless both old and new files
       have been compressed with the same xz version.	This  problem  can  be
       fixed if a part of the encoder implementation is frozen to keep rsynca‐
       ble output stable across xz versions.

   Embedded .xz decompressors
       Embedded .xz decompressor implementations like XZ Embedded don't neces‐
       sarily support files created with integrity check types other than none
       and  crc32.   Since  the	 default  is  --check=crc64,  you   must   use
       --check=none or --check=crc32 when creating files for embedded systems.

       Outside	embedded systems, all .xz format decompressors support all the
       check types, or at least are able to decompress the file without	 veri‐
       fying the integrity check if the particular check is not supported.

       XZ  Embedded supports BCJ filters, but only with the default start off‐
       set.

EXAMPLES
   Basics
       Compress the file foo into foo.xz using the default  compression	 level
       (-6), and remove foo if compression is successful:

	      xz foo

       Decompress  bar.xz  into bar and don't remove bar.xz even if decompres‐
       sion is successful:

	      xz -dk bar.xz

       Create baz.tar.xz with the preset -4e (-4 --extreme), which  is	slower
       than  the  default -6, but needs less memory for compression and decom‐
       pression (48 MiB and 5 MiB, respectively):

	      tar cf - baz | xz -4e > baz.tar.xz

       A mix of compressed and uncompressed files can be decompressed to stan‐
       dard output with a single command:

	      xz -dcf a.txt b.txt.xz c.txt d.txt.lzma > abcd.txt

   Parallel compression of many files
       On  GNU	and *BSD, find(1) and xargs(1) can be used to parallelize com‐
       pression of many files:

	      find . -type f \! -name '*.xz' -print0 \
		  | xargs -0r -P4 -n16 xz -T1

       The -P option to xargs(1) sets the number  of  parallel	xz  processes.
       The best value for the -n option depends on how many files there are to
       be compressed.  If there are only a couple of files, the	 value	should
       probably be 1; with tens of thousands of files, 100 or even more may be
       appropriate to reduce the number of xz  processes  that	xargs(1)  will
       eventually create.

       The option -T1 for xz is there to force it to single-threaded mode, be‐
       cause xargs(1) is used to control the amount of parallelization.

   Robot mode
       Calculate how many bytes have been saved	 in  total  after  compressing
       multiple files:

	      xz --robot --list *.xz | awk '/^totals/{print $5-$4}'

       A  script may want to know that it is using new enough xz.  The follow‐
       ing sh(1) script checks that the version number of the xz  tool	is  at
       least  5.0.0.   This method is compatible with old beta versions, which
       didn't support the --robot option:

	      if ! eval "$(xz --robot --version 2> /dev/null)" ||
		      [ "$XZ_VERSION" -lt 50000002 ]; then
		  echo "Your xz is too old."
	      fi
	      unset XZ_VERSION LIBLZMA_VERSION

       Set a memory usage limit for decompression using XZ_OPT, but if a limit
       has already been set, don't increase it:

	      NEWLIM=$((123 << 20))  # 123 MiB
	      OLDLIM=$(xz --robot --info-memory | cut -f3)
	      if [ $OLDLIM -eq 0 -o $OLDLIM -gt $NEWLIM ]; then
		  XZ_OPT="$XZ_OPT --memlimit-decompress=$NEWLIM"
		  export XZ_OPT
	      fi

   Custom compressor filter chains
       The  simplest  use for custom filter chains is customizing a LZMA2 pre‐
       set.  This can be useful, because the presets cover only	 a  subset  of
       the potentially useful combinations of compression settings.

       The  CompCPU columns of the tables from the descriptions of the options
       -0 ... -9 and --extreme are  useful  when  customizing  LZMA2  presets.
       Here are the relevant parts collected from those two tables:

	      tab(;);  c  c n n.  Preset;CompCPU -0;0 -1;1 -2;2 -3;3 -4;4 -5;5
	      -6;6 -5e;7 -6e;8

       If you know that a file requires somewhat big dictionary (for  example,
       32 MiB)	to  compress well, but you want to compress it quicker than xz
       -8 would do, a preset with a low CompCPU value (for example, 1) can  be
       modified to use a bigger dictionary:

	      xz --lzma2=preset=1,dict=32MiB foo.tar

       With  certain  files,  the above command may be faster than xz -6 while
       compressing significantly better.  However, it must be emphasized  that
       only some files benefit from a big dictionary while keeping the CompCPU
       value low.  The most obvious situation, where a big dictionary can help
       a  lot,	is  an archive containing very similar files of at least a few
       megabytes each.	The dictionary size has	 to  be	 significantly	bigger
       than  any  individual file to allow LZMA2 to take full advantage of the
       similarities between consecutive files.

       If very high compressor and decompressor memory usage is fine, and  the
       file  being compressed is at least several hundred megabytes, it may be
       useful to use an even bigger dictionary than the	 64  MiB  that	xz  -9
       would use:

	      xz -vv --lzma2=dict=192MiB big_foo.tar

       Using -vv (--verbose --verbose) like in the above example can be useful
       to see the memory requirements of the compressor and decompressor.  Re‐
       member that using a dictionary bigger than the size of the uncompressed
       file is waste of memory, so the above command isn't  useful  for	 small
       files.

       Sometimes  the  compression  time  doesn't matter, but the decompressor
       memory usage has to be kept low, for example, to make  it  possible  to
       decompress  the file on an embedded system.  The following command uses
       -6e (-6 --extreme) as a base and sets the dictionary  to	 only  64 KiB.
       The  resulting  file  can  be decompressed with XZ Embedded (that's why
       there is --check=crc32) using about 100 KiB of memory.

	      xz --check=crc32 --lzma2=preset=6e,dict=64KiB foo

       If you want to squeeze out as many bytes	 as  possible,	adjusting  the
       number  of  literal  context bits (lc) and number of position bits (pb)
       can sometimes help.  Adjusting the number of literal position bits (lp)
       might help too, but usually lc and pb are more important.  For example,
       a source code archive contains mostly US-ASCII text, so something  like
       the following might give slightly (like 0.1 %) smaller file than xz -6e
       (try also without lc=4):

	      xz --lzma2=preset=6e,pb=0,lc=4 source_code.tar

       Using another filter together with LZMA2 can improve  compression  with
       certain file types.  For example, to compress a x86-32 or x86-64 shared
       library using the x86 BCJ filter:

	      xz --x86 --lzma2 libfoo.so

       Note that the order of the filter options is significant.  If --x86  is
       specified after --lzma2, xz will give an error, because there cannot be
       any filter after LZMA2, and also because the x86 BCJ filter  cannot  be
       used as the last filter in the chain.

       The  Delta filter together with LZMA2 can give good results with bitmap
       images.	It should usually beat PNG, which has a few more advanced fil‐
       ters than simple delta but uses Deflate for the actual compression.

       The  image  has to be saved in uncompressed format, for example, as un‐
       compressed TIFF.	 The distance parameter of the Delta filter is set  to
       match  the number of bytes per pixel in the image.  For example, 24-bit
       RGB bitmap needs dist=3, and it is also good to pass pb=0 to  LZMA2  to
       accommodate the three-byte alignment:

	      xz --delta=dist=3 --lzma2=pb=0 foo.tiff

       If  multiple  images  have been put into a single archive (for example,
       .tar), the Delta filter will work on that too as	 long  as  all	images
       have the same number of bytes per pixel.

SEE ALSO
       xzdec(1),   xzdiff(1),	xzgrep(1),   xzless(1),	  xzmore(1),  gzip(1),
       bzip2(1), 7z(1)

       XZ Utils: <https://tukaani.org/xz/>
       XZ Embedded: <https://tukaani.org/xz/embedded.html>
       LZMA SDK: <https://7-zip.org/sdk.html>



Tukaani				  2024-12-30				 XZ(1)

XZ(1)				   XZ Utils				 XZ(1)



NAME
       xz,  unxz,  xzcat, lzma, unlzma, lzcat - Compress or decompress .xz and
       .lzma files

SYNOPSIS
       xz [option...]  [file...]

COMMAND ALIASES
       unxz is equivalent to xz --decompress.
       xzcat is equivalent to xz --decompress --stdout.
       lzma is equivalent to xz --format=lzma.
       unlzma is equivalent to xz --format=lzma --decompress.
       lzcat is equivalent to xz --format=lzma --decompress --stdout.

       When writing scripts that need to decompress files, it  is  recommended
       to  always use the name xz with appropriate arguments (xz -d or xz -dc)
       instead of the names unxz and xzcat.

DESCRIPTION
       xz is a general-purpose data compression tool with command line	syntax
       similar	to  gzip(1)  and  bzip2(1).  The native file format is the .xz
       format, but the legacy .lzma format used by LZMA	 Utils	and  raw  com‐
       pressed	streams	 with  no container format headers are also supported.
       In addition, decompression of the .lz format used by lzip is supported.

       xz compresses or decompresses each file according to the selected oper‐
       ation mode.  If no files are given or file is -, xz reads from standard
       input and writes the processed data to standard output.	xz will refuse
       (display	 an error and skip the file) to write compressed data to stan‐
       dard output if it is a terminal.	 Similarly, xz	will  refuse  to  read
       compressed data from standard input if it is a terminal.

       Unless  --stdout	 is specified, files other than - are written to a new
       file whose name is derived from the source file name:

       •  When compressing, the suffix of  the	target	file  format  (.xz  or
	  .lzma)  is  appended	to the source filename to get the target file‐
	  name.

       •  When decompressing, the .xz, .lzma, or .lz suffix  is	 removed  from
	  the  filename	 to  get  the target filename.	xz also recognizes the
	  suffixes .txz and .tlz, and replaces them with the .tar suffix.

       If the target file already exists, an error is displayed and  the  file
       is skipped.

       Unless  writing	to standard output, xz will display a warning and skip
       the file if any of the following applies:

       •  File is not a regular file.  Symbolic links are  not	followed,  and
	  thus they are not considered to be regular files.

       •  File has more than one hard link.

       •  File has setuid, setgid, or sticky bit set.

       •  The  operation  mode	is  set to compress and the file already has a
	  suffix of the target file format (.xz or .txz	 when  compressing  to
	  the .xz format, and .lzma or .tlz when compressing to the .lzma for‐
	  mat).

       •  The operation mode is set to decompress and the file doesn't have  a
	  suffix of any of the supported file formats (.xz, .txz, .lzma, .tlz,
	  or .lz).

       After successfully compressing or decompressing the file, xz copies the
       owner,  group, permissions, access time, and modification time from the
       source file to the target file.	If copying the group fails,  the  per‐
       missions are modified so that the target file doesn't become accessible
       to users who didn't have permission to  access  the  source  file.   xz
       doesn't support copying other metadata like access control lists or ex‐
       tended attributes yet.

       Once the target file has been successfully closed, the source  file  is
       removed	unless --keep was specified.  The source file is never removed
       if the output is written to standard output or if an error occurs.

       Sending SIGINFO or SIGUSR1 to the xz process makes  it  print  progress
       information  to	standard  error.  This has only limited use since when
       standard error is a terminal, using --verbose will display an automati‐
       cally updating progress indicator.

   Memory usage
       The  memory  usage of xz varies from a few hundred kilobytes to several
       gigabytes depending on the compression  settings.   The	settings  used
       when compressing a file determine the memory requirements of the decom‐
       pressor.	 Typically the decompressor needs 5 % to 20 % of the amount of
       memory that the compressor needed when creating the file.  For example,
       decompressing a file created with xz -9 currently  requires  65 MiB  of
       memory.	 Still,	 it is possible to have .xz files that require several
       gigabytes of memory to decompress.

       Especially users of older systems may  find  the	 possibility  of  very
       large  memory  usage  annoying.	To prevent uncomfortable surprises, xz
       has a built-in memory usage limiter,  which  is	disabled  by  default.
       While  some operating systems provide ways to limit the memory usage of
       processes, relying on it wasn't deemed to be flexible enough (for exam‐
       ple, using ulimit(1) to limit virtual memory tends to cripple mmap(2)).

       The  memory  usage  limiter can be enabled with the command line option
       --memlimit=limit.  Often it is more convenient to enable the limiter by
       default	by  setting the environment variable XZ_DEFAULTS, for example,
       XZ_DEFAULTS=--memlimit=150MiB.  It is possible to set the limits	 sepa‐
       rately  for  compression	 and  decompression  by	 using --memlimit-com‐
       press=limit and --memlimit-decompress=limit.  Using these  two  options
       outside	XZ_DEFAULTS is rarely useful because a single run of xz cannot
       do both compression  and	 decompression	and  --memlimit=limit  (or  -M
       limit) is shorter to type on the command line.

       If  the specified memory usage limit is exceeded when decompressing, xz
       will display an error and decompressing the file	 will  fail.   If  the
       limit  is  exceeded when compressing, xz will try to scale the settings
       down so that the limit is no longer exceeded (except when using	--for‐
       mat=raw	or --no-adjust).  This way the operation won't fail unless the
       limit is very small.  The scaling of the settings is done in steps that
       don't match the compression level presets, for example, if the limit is
       only slightly less than the amount required for	xz  -9,	 the  settings
       will be scaled down only a little, not all the way down to xz -8.

   Concatenation and padding with .xz files
       It is possible to concatenate .xz files as is.  xz will decompress such
       files as if they were a single .xz file.

       It is possible to insert padding between the concatenated parts or  af‐
       ter the last part.  The padding must consist of null bytes and the size
       of the padding must be a multiple of four bytes.	 This can  be  useful,
       for  example,  if the .xz file is stored on a medium that measures file
       sizes in 512-byte blocks.

       Concatenation and padding are not  allowed  with	 .lzma	files  or  raw
       streams.

OPTIONS
   Integer suffixes and special values
       In  most places where an integer argument is expected, an optional suf‐
       fix is supported to easily indicate large integers.  There must	be  no
       space between the integer and the suffix.

       KiB    Multiply	the integer by 1,024 (2^10).  Ki, k, kB, K, and KB are
	      accepted as synonyms for KiB.

       MiB    Multiply the integer by 1,048,576 (2^20).	 Mi, m, M, and MB  are
	      accepted as synonyms for MiB.

       GiB    Multiply	the integer by 1,073,741,824 (2^30).  Gi, g, G, and GB
	      are accepted as synonyms for GiB.

       The special value max can be used to indicate the maximum integer value
       supported by the option.

   Operation mode
       If  multiple  operation	mode options are given, the last one takes ef‐
       fect.

       -z, --compress
	      Compress.	 This is the default operation mode when no  operation
	      mode  option is specified and no other operation mode is implied
	      from the command name (for example, unxz implies --decompress).

	      After successful compression, the source file is removed	unless
	      writing to standard output or --keep was specified.

       -d, --decompress, --uncompress
	      Decompress.   After successful decompression, the source file is
	      removed unless writing to standard output or --keep  was	speci‐
	      fied.

       -t, --test
	      Test  the integrity of compressed files.	This option is equiva‐
	      lent to --decompress --stdout except that the decompressed  data
	      is  discarded  instead  of being written to standard output.  No
	      files are created or removed.

       -l, --list
	      Print information about compressed files.	 No uncompressed  out‐
	      put  is  produced, and no files are created or removed.  In list
	      mode, the program cannot read the compressed data from  standard
	      input or from other unseekable sources.

	      The  default  listing  shows  basic information about files, one
	      file per line.  To get more detailed information, use  also  the
	      --verbose	 option.   For	even  more  information, use --verbose
	      twice, but note that this may be slow, because getting  all  the
	      extra  information  requires  many  seeks.  The width of verbose
	      output exceeds 80 characters, so piping the output to, for exam‐
	      ple,  less -S  may  be  convenient  if  the  terminal isn't wide
	      enough.

	      The exact output may vary between xz versions and different  lo‐
	      cales.   For  machine-readable  output, --robot --list should be
	      used.

   Operation modifiers
       -k, --keep
	      Don't delete the input files.

	      Since xz 5.2.6, this option also makes xz compress or decompress
	      even if the input is a symbolic link to a regular file, has more
	      than one hard link, or has the setuid,  setgid,  or  sticky  bit
	      set.   The setuid, setgid, and sticky bits are not copied to the
	      target file.  In	earlier	 versions  this	 was  only  done  with
	      --force.

       -f, --force
	      This option has several effects:

	      •	 If the target file already exists, delete it before compress‐
		 ing or decompressing.

	      •	 Compress or decompress even if the input is a	symbolic  link
		 to  a	regular	 file, has more than one hard link, or has the
		 setuid, setgid, or sticky bit set.  The setuid,  setgid,  and
		 sticky bits are not copied to the target file.

	      •	 When  used with --decompress --stdout and xz cannot recognize
		 the type of the source file, copy the source file  as	is  to
		 standard  output.   This allows xzcat --force to be used like
		 cat(1) for files that have not been compressed with xz.  Note
		 that in future, xz might support new compressed file formats,
		 which may make xz decompress more types of files  instead  of
		 copying  them	as is to standard output.  --format=format can
		 be used to restrict xz to decompress only a single file  for‐
		 mat.

       -c, --stdout, --to-stdout
	      Write the compressed or decompressed data to standard output in‐
	      stead of a file.	This implies --keep.

       --single-stream
	      Decompress only the first .xz stream, and silently ignore possi‐
	      ble  remaining  input  data following the stream.	 Normally such
	      trailing garbage makes xz display an error.

	      xz never decompresses more than one stream from .lzma  files  or
	      raw  streams, but this option still makes xz ignore the possible
	      trailing data after the .lzma file or raw stream.

	      This option has no effect if the operation mode is not  --decom‐
	      press or --test.

       --no-sparse
	      Disable  creation of sparse files.  By default, if decompressing
	      into a regular file, xz tries to make the file sparse if the de‐
	      compressed  data	contains  long	sequences of binary zeros.  It
	      also works when writing to standard output as long  as  standard
	      output  is  connected  to	 a regular file and certain additional
	      conditions are met to make it safe.  Creating sparse  files  may
	      save  disk  space and speed up the decompression by reducing the
	      amount of disk I/O.

       -S .suf, --suffix=.suf
	      When compressing, use .suf as the suffix for the target file in‐
	      stead  of	 .xz  or .lzma.	 If not writing to standard output and
	      the source file already has the suffix .suf, a warning  is  dis‐
	      played and the file is skipped.

	      When  decompressing, recognize files with the suffix .suf in ad‐
	      dition to files with the .xz, .txz, .lzma, .tlz, or .lz  suffix.
	      If the source file has the suffix .suf, the suffix is removed to
	      get the target filename.

	      When compressing or decompressing	 raw  streams  (--format=raw),
	      the  suffix  must always be specified unless writing to standard
	      output, because there is no default suffix for raw streams.

       --files[=file]
	      Read the filenames to process from file;	if  file  is  omitted,
	      filenames	 are read from standard input.	Filenames must be ter‐
	      minated with the newline character.  A dash (-) is  taken	 as  a
	      regular  filename; it doesn't mean standard input.  If filenames
	      are given also as command line arguments, they are processed be‐
	      fore the filenames read from file.

       --files0[=file]
	      This  is	identical  to --files[=file] except that each filename
	      must be terminated with the null character.

   Basic file format and compression options
       -F format, --format=format
	      Specify the file format to compress or decompress:

	      auto   This is the default.  When compressing, auto  is  equiva‐
		     lent  to xz.  When decompressing, the format of the input
		     file is automatically detected.  Note  that  raw  streams
		     (created with --format=raw) cannot be auto-detected.

	      xz     Compress to the .xz file format, or accept only .xz files
		     when decompressing.

	      lzma, alone
		     Compress to the legacy .lzma file format, or accept  only
		     .lzma  files  when	 decompressing.	  The alternative name
		     alone is provided for backwards compatibility  with  LZMA
		     Utils.

	      lzip   Accept only .lz files when decompressing.	Compression is
		     not supported.

		     The .lz format version 0 and the unextended version 1 are
		     supported.	 Version 0 files were produced by lzip 1.3 and
		     older.  Such files aren't common but may  be  found  from
		     file  archives  as a few source packages were released in
		     this format.  People might have  old  personal  files  in
		     this  format  too.	  Decompression support for the format
		     version 0 was removed in lzip 1.18.

		     lzip 1.4 and later create files in the format version  1.
		     The  sync	flush marker extension to the format version 1
		     was added in lzip 1.6.  This extension is rarely used and
		     isn't supported by xz (diagnosed as corrupt input).

	      raw    Compress  or  uncompress a raw stream (no headers).  This
		     is meant for advanced users only.	To decode raw streams,
		     you need use --format=raw and explicitly specify the fil‐
		     ter chain, which normally would have been stored  in  the
		     container headers.

       -C check, --check=check
	      Specify  the  type  of the integrity check.  The check is calcu‐
	      lated from the uncompressed data and stored  in  the  .xz	 file.
	      This  option  has	 an  effect only when compressing into the .xz
	      format; the .lzma format doesn't support integrity checks.   The
	      integrity check (if any) is verified when the .xz file is decom‐
	      pressed.

	      Supported check types:

	      none   Don't calculate an integrity check at all.	 This is  usu‐
		     ally  a  bad  idea.  This can be useful when integrity of
		     the data is verified by other means anyway.

	      crc32  Calculate CRC32  using  the  polynomial  from  IEEE-802.3
		     (Ethernet).

	      crc64  Calculate CRC64 using the polynomial from ECMA-182.  This
		     is the default, since it is slightly better than CRC32 at
		     detecting	damaged files and the speed difference is neg‐
		     ligible.

	      sha256 Calculate SHA-256.	 This is somewhat  slower  than	 CRC32
		     and CRC64.

	      Integrity	 of the .xz headers is always verified with CRC32.  It
	      is not possible to change or disable it.

       --ignore-check
	      Don't verify the integrity check of the compressed data when de‐
	      compressing.   The CRC32 values in the .xz headers will still be
	      verified normally.

	      Do not use this option unless you know what you are doing.  Pos‐
	      sible reasons to use this option:

	      •	 Trying to recover data from a corrupt .xz file.

	      •	 Speeding  up decompression.  This matters mostly with SHA-256
		 or with files that have compressed extremely well.  It's rec‐
		 ommended  to  not use this option for this purpose unless the
		 file integrity is verified externally in some other way.

       -0 ... -9
	      Select a compression preset level.  The default is -6.  If  mul‐
	      tiple  preset  levels  are specified, the last one takes effect.
	      If a custom filter chain was already specified, setting  a  com‐
	      pression preset level clears the custom filter chain.

	      The  differences	between	 the presets are more significant than
	      with gzip(1) and bzip2(1).  The  selected	 compression  settings
	      determine	 the memory requirements of the decompressor, thus us‐
	      ing a too high preset level might make it painful to  decompress
	      the  file	 on an old system with little RAM.  Specifically, it's
	      not a good idea to blindly use -9 for everything like  it	 often
	      is with gzip(1) and bzip2(1).

	      -0 ... -3
		     These  are somewhat fast presets.	-0 is sometimes faster
		     than gzip -9 while compressing much better.   The	higher
		     ones  often have speed comparable to bzip2(1) with compa‐
		     rable or better compression ratio, although  the  results
		     depend a lot on the type of data being compressed.

	      -4 ... -6
		     Good  to very good compression while keeping decompressor
		     memory usage reasonable even for old systems.  -6 is  the
		     default,  which is usually a good choice for distributing
		     files that need to be decompressible even on systems with
		     only  16 MiB  RAM.	  (-5e or -6e may be worth considering
		     too.  See --extreme.)

	      -7 ... -9
		     These are like -6 but with higher compressor  and	decom‐
		     pressor  memory requirements.  These are useful only when
		     compressing files bigger than 8 MiB, 16 MiB, and  32 MiB,
		     respectively.

	      On the same hardware, the decompression speed is approximately a
	      constant number of bytes of  compressed  data  per  second.   In
	      other  words,  the better the compression, the faster the decom‐
	      pression will usually be.	 This also means that  the  amount  of
	      uncompressed output produced per second can vary a lot.

	      The following table summarises the features of the presets:

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem -0;256 KiB;0;3 MiB;1 MiB -1;1 MiB;1;9
		     MiB;2 MiB -2;2 MiB;2;17 MiB;3 MiB -3;4 MiB;3;32 MiB;5 MiB
		     -4;4 MiB;4;48 MiB;5 MiB  -5;8  MiB;5;94  MiB;9  MiB  -6;8
		     MiB;6;94  MiB;9  MiB  -7;16  MiB;6;186  MiB;17  MiB -8;32
		     MiB;6;370 MiB;33 MiB -9;64 MiB;6;674 MiB;65 MiB

	      Column descriptions:

	      •	 DictSize is the LZMA2 dictionary size.	 It is waste of memory
		 to  use a dictionary bigger than the size of the uncompressed
		 file.	This is why it is good to avoid using the  presets  -7
		 ...  -9 when there's no real need for them.  At -6 and lower,
		 the amount of memory wasted is usually low enough to not mat‐
		 ter.

	      •	 CompCPU  is a simplified representation of the LZMA2 settings
		 that affect compression speed.	 The dictionary	 size  affects
		 speed too, so while CompCPU is the same for levels -6 ... -9,
		 higher levels still tend to be a little slower.  To get  even
		 slower and thus possibly better compression, see --extreme.

	      •	 CompMem  contains  the	 compressor memory requirements in the
		 single-threaded mode.	It may vary slightly between  xz  ver‐
		 sions.

	      •	 DecMem	 contains  the decompressor memory requirements.  That
		 is, the compression settings determine	 the  memory  require‐
		 ments of the decompressor.  The exact decompressor memory us‐
		 age is slightly more than the LZMA2 dictionary size, but  the
		 values	 in  the  table	 have been rounded up to the next full
		 MiB.

	      Memory requirements of the multi-threaded mode are significantly
	      higher  than that of the single-threaded mode.  With the default
	      value of --block-size, each thread needs 3*3*DictSize plus Comp‐
	      Mem  or  DecMem.	For example, four threads with preset -6 needs
	      660–670 MiB of memory.

       -e, --extreme
	      Use a slower variant of the selected  compression	 preset	 level
	      (-0 ... -9) to hopefully get a little bit better compression ra‐
	      tio, but with bad luck this can also make it worse.   Decompres‐
	      sor  memory  usage  is not affected, but compressor memory usage
	      increases a little at preset levels -0 ... -3.

	      Since there are two presets  with	 dictionary  sizes  4 MiB  and
	      8 MiB,  the  presets  -3e	 and  -5e use slightly faster settings
	      (lower CompCPU) than -4e and -6e, respectively.  That way no two
	      presets are identical.

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem  -0e;256  KiB;8;4  MiB;1  MiB	 -1e;1
		     MiB;8;13	MiB;2  MiB  -2e;2  MiB;8;25  MiB;3  MiB	 -3e;4
		     MiB;7;48  MiB;5  MiB  -4e;4  MiB;8;48  MiB;5  MiB	 -5e;8
		     MiB;7;94  MiB;9  MiB  -6e;8  MiB;8;94  MiB;9  MiB	-7e;16
		     MiB;8;186 MiB;17 MiB -8e;32 MiB;8;370 MiB;33  MiB	-9e;64
		     MiB;8;674 MiB;65 MiB

	      For  example,  there  are a total of four presets that use 8 MiB
	      dictionary, whose order from the fastest to the slowest  is  -5,
	      -6, -5e, and -6e.

       --fast
       --best These  are  somewhat  misleading	aliases for -0 and -9, respec‐
	      tively.  These are provided  only	 for  backwards	 compatibility
	      with LZMA Utils.	Avoid using these options.

       --block-size=size
	      When  compressing	 to  the .xz format, split the input data into
	      blocks of size bytes.  The blocks are  compressed	 independently
	      from each other, which helps with multi-threading and makes lim‐
	      ited random-access decompression possible.  This option is typi‐
	      cally  used to override the default block size in multi-threaded
	      mode, but this option can be used in single-threaded mode too.

	      In multi-threaded mode about three times size bytes will be  al‐
	      located  in each thread for buffering input and output.  The de‐
	      fault size is three times the LZMA2 dictionary size  or  1  MiB,
	      whichever is more.  Typically a good value is 2–4 times the size
	      of the LZMA2 dictionary or at least 1 MiB.  Using size less than
	      the LZMA2 dictionary size is waste of RAM because then the LZMA2
	      dictionary buffer will never get fully used.  In	multi-threaded
	      mode,  the  sizes of the blocks are stored in the block headers.
	      This size information is required for multi-threaded  decompres‐
	      sion.

	      In  single-threaded  mode no block splitting is done by default.
	      Setting this option doesn't affect memory usage.	No size infor‐
	      mation is stored in block headers, thus files created in single-
	      threaded mode won't be identical	to  files  created  in	multi-
	      threaded	mode.  The lack of size information also means that xz
	      won't be able decompress the files in multi-threaded mode.

       --block-list=items
	      When compressing to the .xz format, start a new  block  with  an
	      optional custom filter chain after the given intervals of uncom‐
	      pressed data.

	      The items are a comma-separated list.  Each item consists of  an
	      optional filter chain number between 0 and 9 followed by a colon
	      (:) and a required size of uncompressed data.  Omitting an  item
	      (two  or more consecutive commas) is a shorthand to use the size
	      and filters of the previous item.

	      If the input file is bigger than the sum of the sizes in	items,
	      the  last item is repeated until the end of the file.  A special
	      value of 0 may be used as the last size  to  indicate  that  the
	      rest of the file should be encoded as a single block.

	      An  alternative  filter chain for each block can be specified in
	      combination with the --filters1=filters  ...  --filters9=filters
	      options.	 These options define filter chains with an identifier
	      between 1–9.  Filter chain 0 can be used to refer to the default
	      filter  chain,  which  is	 the  same  as not specifying a filter
	      chain.  The filter chain identifier can be used before  the  un‐
	      compressed  size,	 followed by a colon (:).  For example, if one
	      specifies	 --block-list=1:2MiB,3:2MiB,2:4MiB,,2MiB,0:4MiB	  then
	      blocks will be created using:

	      •	 The filter chain specified by --filters1 and 2 MiB input

	      •	 The filter chain specified by --filters3 and 2 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The default filter chain and 2 MiB input

	      •	 The  default filter chain and 4 MiB input for every block un‐
		 til end of input.

	      If one specifies a size that exceeds the	encoder's  block  size
	      (either  the  default value in threaded mode or the value speci‐
	      fied with --block-size=size), the encoder will create additional
	      blocks while keeping the boundaries specified in items.  For ex‐
	      ample,	  if	  one	    specifies	    --block-size=10MiB
	      --block-list=5MiB,10MiB,8MiB,12MiB,24MiB	and  the input file is
	      80 MiB, one will get 11 blocks: 5, 10, 8, 10, 2, 10, 10, 4,  10,
	      10, and 1 MiB.

	      In multi-threaded mode the sizes of the blocks are stored in the
	      block headers.  This isn't done in single-threaded mode, so  the
	      encoded  output won't be identical to that of the multi-threaded
	      mode.

       --flush-timeout=timeout
	      When compressing, if more than timeout milliseconds (a  positive
	      integer)	has  passed  since the previous flush and reading more
	      input would block, all the pending input data  is	 flushed  from
	      the  encoder  and made available in the output stream.  This can
	      be useful if xz is used to compress data that is streamed over a
	      network.	 Small	timeout	 values make the data available at the
	      receiving end with a small delay, but large timeout values  give
	      better compression ratio.

	      This  feature  is disabled by default.  If this option is speci‐
	      fied more than once, the last one	 takes	effect.	  The  special
	      timeout  value  of 0 can be used to explicitly disable this fea‐
	      ture.

	      This feature is not available on non-POSIX systems.

	      This feature is still experimental.  Currently xz is  unsuitable
	      for  decompressing  the  stream  in real time due to how xz does
	      buffering.

       --memlimit-compress=limit
	      Set a memory usage limit for compression.	  If  this  option  is
	      specified multiple times, the last one takes effect.

	      If the compression settings exceed the limit, xz will attempt to
	      adjust the settings downwards so that the limit is no longer ex‐
	      ceeded  and display a notice that automatic adjustment was done.
	      The adjustments are done in this order: reducing the  number  of
	      threads, switching to single-threaded mode if even one thread in
	      multi-threaded mode exceeds the limit, and finally reducing  the
	      LZMA2 dictionary size.

	      When  compressing	 with  --format=raw or if --no-adjust has been
	      specified, only the number of threads may be  reduced  since  it
	      can be done without affecting the compressed output.

	      If  the  limit cannot be met even with the adjustments described
	      above, an error is displayed and xz will exit with  exit	status
	      1.

	      The limit can be specified in multiple ways:

	      •	 The  limit can be an absolute value in bytes.	Using an inte‐
		 ger suffix like MiB can be useful.  Example:  --memlimit-com‐
		 press=80MiB

	      •	 The  limit can be specified as a percentage of total physical
		 memory (RAM).	This can be useful especially when setting the
		 XZ_DEFAULTS  environment  variable  in a shell initialization
		 script that is shared between different computers.  That  way
		 the  limit  is automatically bigger on systems with more mem‐
		 ory.  Example: --memlimit-compress=70%

	      •	 The limit can be reset back to its default value  by  setting
		 it  to	 0.  This is currently equivalent to setting the limit
		 to max (no memory usage limit).

	      For 32-bit xz there is a special case: if	 the  limit  would  be
	      over 4020 MiB, the limit is set to 4020 MiB.  On MIPS32 2000 MiB
	      is used instead.	(The values 0 and max aren't affected by this.
	      A similar feature doesn't exist for decompression.)  This can be
	      helpful when a 32-bit executable has  access  to	4 GiB  address
	      space  (2	 GiB on MIPS32) while hopefully doing no harm in other
	      situations.

	      See also the section Memory usage.

       --memlimit-decompress=limit
	      Set a memory usage limit for decompression.  This	 also  affects
	      the  --list  mode.  If the operation is not possible without ex‐
	      ceeding the limit, xz will display an  error  and	 decompressing
	      the  file will fail.  See --memlimit-compress=limit for possible
	      ways to specify the limit.

       --memlimit-mt-decompress=limit
	      Set a memory usage limit for multi-threaded decompression.  This
	      can  only	 affect the number of threads; this will never make xz
	      refuse to decompress a file.  If limit is too low to  allow  any
	      multi-threading,	the  limit  is ignored and xz will continue in
	      single-threaded mode.  Note that if  also	 --memlimit-decompress
	      is used, it will always apply to both single-threaded and multi-
	      threaded modes, and so the effective limit  for  multi-threading
	      will  never  be higher than the limit set with --memlimit-decom‐
	      press.

	      In contrast to the other	memory	usage  limit  options,	--mem‐
	      limit-mt-decompress=limit	 has  a system-specific default limit.
	      xz --info-memory can be used to see the current value.

	      This option and its default  value  exist	 because  without  any
	      limit  the  threaded decompressor could end up allocating an in‐
	      sane amount of memory with some input  files.   If  the  default
	      limit is too low on your system, feel free to increase the limit
	      but never set it to a value larger than the amount of usable RAM
	      as  with	appropriate  input  files  xz will attempt to use that
	      amount of memory even with a low number of threads.  Running out
	      of  memory  or  swapping	will not improve decompression perfor‐
	      mance.

	      See --memlimit-compress=limit for possible ways to  specify  the
	      limit.   Setting limit to 0 resets the limit to the default sys‐
	      tem-specific value.

       -M limit, --memlimit=limit, --memory=limit
	      This  is	equivalent  to	specifying   --memlimit-compress=limit
	      --memlimit-decompress=limit --memlimit-mt-decompress=limit.

       --no-adjust
	      Display  an  error  and exit if the memory usage limit cannot be
	      met without adjusting settings that affect the  compressed  out‐
	      put.   That is, this prevents xz from switching the encoder from
	      multi-threaded mode to single-threaded mode  and	from  reducing
	      the  LZMA2  dictionary  size.  Even when this option is used the
	      number of threads may be reduced to meet the memory usage	 limit
	      as that won't affect the compressed output.

	      Automatic adjusting is always disabled when creating raw streams
	      (--format=raw).

       -T threads, --threads=threads
	      Specify the number of worker threads to use.  Setting threads to
	      a special value 0 makes xz use up to as many threads as the pro‐
	      cessor(s) on the system support.	The actual number  of  threads
	      can  be  fewer  than threads if the input file is not big enough
	      for threading with the given settings or if using	 more  threads
	      would exceed the memory usage limit.

	      The  single-threaded and multi-threaded compressors produce dif‐
	      ferent output.  Single-threaded compressor will give the	small‐
	      est  file	 size but only the output from the multi-threaded com‐
	      pressor can be decompressed  using  multiple  threads.   Setting
	      threads to 1 will use the single-threaded mode.  Setting threads
	      to any other value, including 0,	will  use  the	multi-threaded
	      compressor even if the system supports only one hardware thread.
	      (xz 5.2.x used single-threaded mode in this situation.)

	      To use multi-threaded mode with only one thread, set threads  to
	      +1.   The	 +  prefix  has no effect with values other than 1.  A
	      memory usage limit can still make xz switch  to  single-threaded
	      mode  unless  --no-adjust is used.  Support for the + prefix was
	      added in xz 5.4.0.

	      If an automatic number of threads has been requested and no mem‐
	      ory  usage  limit has been specified, then a system-specific de‐
	      fault soft limit will be used to possibly limit  the  number  of
	      threads.	 It is a soft limit in sense that it is ignored if the
	      number of threads becomes one, thus a soft limit will never stop
	      xz  from	compressing or decompressing.  This default soft limit
	      will not make xz switch  from  multi-threaded  mode  to  single-
	      threaded	 mode.	  The  active  limits  can  be	seen  with  xz
	      --info-memory.

	      Currently the only threading method is to split the  input  into
	      blocks and compress them independently from each other.  The de‐
	      fault block size depends on the compression  level  and  can  be
	      overridden with the --block-size=size option.

	      Threaded decompression only works on files that contain multiple
	      blocks with size information in block headers.  All large enough
	      files compressed in multi-threaded mode meet this condition, but
	      files  compressed	 in  single-threaded  mode   don't   even   if
	      --block-size=size has been used.

	      The  default  value for threads is 0.  In xz 5.4.x and older the
	      default is 1.

   Custom compressor filter chains
       A custom filter chain allows specifying the compression settings in de‐
       tail  instead  of  relying  on  the settings associated to the presets.
       When a custom filter chain is specified, preset options (-0 ... -9  and
       --extreme)  earlier on the command line are forgotten.  If a preset op‐
       tion is specified after one or more custom filter  chain	 options,  the
       new  preset  takes effect and the custom filter chain options specified
       earlier are forgotten.

       A filter chain is comparable to piping on the command line.  When  com‐
       pressing, the uncompressed input goes to the first filter, whose output
       goes to the next filter (if any).  The output of the last  filter  gets
       written	to  the compressed file.  The maximum number of filters in the
       chain is four, but typically a filter chain has only one	 or  two  fil‐
       ters.

       Many filters have limitations on where they can be in the filter chain:
       some filters can work only as the last filter in the chain,  some  only
       as  a non-last filter, and some work in any position in the chain.  De‐
       pending on the filter, this limitation is either inherent to the filter
       design or exists to prevent security issues.

       A  custom filter chain can be specified in two different ways.  The op‐
       tions --filters=filters and --filters1=filters  ...  --filters9=filters
       allow specifying an entire filter chain in one option using the liblzma
       filter string syntax.  Alternatively, a filter chain can	 be  specified
       by  using  one  or more individual filter options in the order they are
       wanted in the filter chain.  That is, the order of the individual  fil‐
       ter  options is significant!  When decoding raw streams (--format=raw),
       the filter chain must be specified in the same order as it  was	speci‐
       fied  when compressing.	Any individual filter or preset options speci‐
       fied before the full chain option (--filters=filters) will  be  forgot‐
       ten.  Individual filters specified after the full chain option will re‐
       set the filter chain.

       Both the full and individual filter options  take  filter-specific  op‐
       tions  as a comma-separated list.  Extra commas in options are ignored.
       Every option has a default value, so specify those you want to change.

       To see the whole filter chain and options, use xz  -vv  (that  is,  use
       --verbose twice).  This works also for viewing the filter chain options
       used by presets.

       --filters=filters
	      Specify the full filter chain or a preset in  a  single  option.
	      Each filter can be separated by spaces or two dashes (--).  fil‐
	      ters may need to be quoted on the shell command line  so	it  is
	      parsed  as  a  single option.  To denote options, use : or =.  A
	      preset can be prefixed with a - and followed with zero  or  more
	      flags.   The  only supported flag is e to apply the same options
	      as --extreme.

       --filters1=filters ... --filters9=filters
	      Specify up to nine additional filter chains  that	 can  be  used
	      with --block-list.

	      For  example,  when compressing an archive with executable files
	      followed by text files, the executable part could use  a	filter
	      chain with a BCJ filter and the text part only the LZMA2 filter.

       --filters-help
	      Display  a  help	message	 describing how to specify presets and
	      custom filter chains in the --filters and --filters1=filters ...
	      --filters9=filters options, and exit successfully.

       --lzma1[=options]
       --lzma2[=options]
	      Add  LZMA1  or  LZMA2 filter to the filter chain.	 These filters
	      can be used only as the last filter in the chain.

	      LZMA1 is a legacy filter, which is supported almost  solely  due
	      to  the  legacy  .lzma  file  format, which supports only LZMA1.
	      LZMA2 is an updated version of LZMA1 to fix some	practical  is‐
	      sues  of	LZMA1.	 The .xz format uses LZMA2 and doesn't support
	      LZMA1 at all.  Compression speed and ratios of LZMA1  and	 LZMA2
	      are practically the same.

	      LZMA1 and LZMA2 share the same set of options:

	      preset=preset
		     Reset  all LZMA1 or LZMA2 options to preset.  Preset con‐
		     sist of an integer, which may be followed by  single-let‐
		     ter  preset  modifiers.   The integer can be from 0 to 9,
		     matching the command line options -0 ...  -9.   The  only
		     supported	modifier  is  currently e, which matches --ex‐
		     treme.  If no preset is specified, the default values  of
		     LZMA1 or LZMA2 options are taken from the preset 6.

	      dict=size
		     Dictionary (history buffer) size indicates how many bytes
		     of the recently processed uncompressed data  is  kept  in
		     memory.   The  algorithm tries to find repeating byte se‐
		     quences (matches) in the uncompressed data,  and  replace
		     them with references to the data currently in the dictio‐
		     nary.  The bigger	the  dictionary,  the  higher  is  the
		     chance to find a match.  Thus, increasing dictionary size
		     usually improves compression ratio, but a dictionary big‐
		     ger than the uncompressed file is waste of memory.

		     Typical  dictionary  size	is from 64 KiB to 64 MiB.  The
		     minimum is 4 KiB.	The maximum for	 compression  is  cur‐
		     rently 1.5 GiB (1536 MiB).	 The decompressor already sup‐
		     ports dictionaries up to one byte less than 4 GiB,	 which
		     is the maximum for the LZMA1 and LZMA2 stream formats.

		     Dictionary	 size and match finder (mf) together determine
		     the memory usage of the LZMA1 or LZMA2 encoder.  The same
		     (or bigger) dictionary size is required for decompressing
		     that was used when compressing, thus the memory usage  of
		     the  decoder  is  determined  by the dictionary size used
		     when compressing.	The .xz headers store  the  dictionary
		     size  either  as 2^n or 2^n + 2^(n-1), so these sizes are
		     somewhat preferred for compression.  Other sizes will get
		     rounded up when stored in the .xz headers.

	      lc=lc  Specify  the number of literal context bits.  The minimum
		     is 0 and the maximum is 4; the default is	3.   In	 addi‐
		     tion, the sum of lc and lp must not exceed 4.

		     All  bytes	 that cannot be encoded as matches are encoded
		     as literals.  That is, literals are  simply  8-bit	 bytes
		     that are encoded one at a time.

		     The  literal  coding makes an assumption that the highest
		     lc bits of the previous uncompressed byte correlate  with
		     the  next byte.  For example, in typical English text, an
		     upper-case letter is often followed by a lower-case  let‐
		     ter,  and	a lower-case letter is usually followed by an‐
		     other lower-case letter.  In the US-ASCII character  set,
		     the highest three bits are 010 for upper-case letters and
		     011 for lower-case letters.  When lc is at least  3,  the
		     literal coding can take advantage of this property in the
		     uncompressed data.

		     The default value (3) is usually good.  If you want maxi‐
		     mum compression, test lc=4.  Sometimes it helps a little,
		     and sometimes it makes compression worse.	If it makes it
		     worse, test lc=2 too.

	      lp=lp  Specify the number of literal position bits.  The minimum
		     is 0 and the maximum is 4; the default is 0.

		     Lp affects what kind of  alignment	 in  the  uncompressed
		     data is assumed when encoding literals.  See pb below for
		     more information about alignment.

	      pb=pb  Specify the number of position bits.  The	minimum	 is  0
		     and the maximum is 4; the default is 2.

		     Pb	 affects  what	kind  of alignment in the uncompressed
		     data is assumed in general.  The default means  four-byte
		     alignment (2^pb=2^2=4), which is often a good choice when
		     there's no better guess.

		     When the alignment is known, setting pb  accordingly  may
		     reduce  the  file	size a little.	For example, with text
		     files having one-byte  alignment  (US-ASCII,  ISO-8859-*,
		     UTF-8),  setting  pb=0  can improve compression slightly.
		     For UTF-16 text, pb=1 is a good choice.  If the alignment
		     is	 an  odd  number  like 3 bytes, pb=0 might be the best
		     choice.

		     Even though the assumed alignment can be adjusted with pb
		     and  lp,  LZMA1  and  LZMA2  still slightly favor 16-byte
		     alignment.	 It might be worth taking  into	 account  when
		     designing	file  formats that are likely to be often com‐
		     pressed with LZMA1 or LZMA2.

	      mf=mf  Match finder has a major effect on encoder speed,	memory
		     usage,  and  compression ratio.  Usually Hash Chain match
		     finders are faster than Binary Tree match	finders.   The
		     default  depends  on the preset: 0 uses hc3, 1–3 use hc4,
		     and the rest use bt4.

		     The following match finders are  supported.   The	memory
		     usage  formulas below are rough approximations, which are
		     closest to the reality when dict is a power of two.

		     hc3    Hash Chain with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 7.5 (if dict <= 16 MiB);
			    dict * 5.5 + 64 MiB (if dict > 16 MiB)

		     hc4    Hash Chain with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 7.5 (if dict <= 32 MiB);
			    dict * 6.5 (if dict > 32 MiB)

		     bt2    Binary Tree with 2-byte hashing
			    Minimum value for nice: 2
			    Memory usage: dict * 9.5

		     bt3    Binary Tree with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 11.5 (if dict <= 16 MiB);
			    dict * 9.5 + 64 MiB (if dict > 16 MiB)

		     bt4    Binary Tree with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 11.5 (if dict <= 32 MiB);
			    dict * 10.5 (if dict > 32 MiB)

	      mode=mode
		     Compression mode specifies the method to analyze the data
		     produced  by  the match finder.  Supported modes are fast
		     and normal.  The default is fast for presets 0–3 and nor‐
		     mal for presets 4–9.

		     Usually  fast  is	used with Hash Chain match finders and
		     normal with Binary Tree match finders.  This is also what
		     the presets do.

	      nice=nice
		     Specify  what  is	considered  to	be a nice length for a
		     match.  Once a match of at least nice bytes is found, the
		     algorithm stops looking for possibly better matches.

		     Nice can be 2–273 bytes.  Higher values tend to give bet‐
		     ter compression ratio at the expense of speed.   The  de‐
		     fault depends on the preset.

	      depth=depth
		     Specify  the  maximum  search  depth in the match finder.
		     The default is the special value of 0,  which  makes  the
		     compressor determine a reasonable depth from mf and nice.

		     Reasonable depth for Hash Chains is 4–100 and 16–1000 for
		     Binary Trees.  Using very high values for depth can  make
		     the  encoder  extremely slow with some files.  Avoid set‐
		     ting the depth over 1000 unless you are prepared  to  in‐
		     terrupt  the  compression	in  case  it is taking far too
		     long.

	      When decoding raw streams (--format=raw), LZMA2 needs  only  the
	      dictionary size.	LZMA1 needs also lc, lp, and pb.

       --x86[=options]
       --arm[=options]
       --armthumb[=options]
       --arm64[=options]
       --powerpc[=options]
       --ia64[=options]
       --sparc[=options]
       --riscv[=options]
	      Add  a branch/call/jump (BCJ) filter to the filter chain.	 These
	      filters can be used only as a  non-last  filter  in  the	filter
	      chain.

	      A	 BCJ filter converts relative addresses in the machine code to
	      their absolute counterparts.  This doesn't change	 the  size  of
	      the  data	 but  it increases redundancy, which can help LZMA2 to
	      produce 0–15 % smaller .xz file.	The BCJ filters are always re‐
	      versible,	 so  using a BCJ filter for wrong type of data doesn't
	      cause any data loss, although it may make the compression	 ratio
	      slightly	worse.	 The  BCJ filters are very fast and use an in‐
	      significant amount of memory.

	      These BCJ filters have known problems related to the compression
	      ratio:

	      •	 Some  types of files containing executable code (for example,
		 object files, static libraries,  and  Linux  kernel  modules)
		 have  the  addresses  in  the instructions filled with filler
		 values.  These BCJ filters will still do the address  conver‐
		 sion, which will make the compression worse with these files.

	      •	 If a BCJ filter is applied on an archive, it is possible that
		 it makes the compression ratio worse than  not	 using	a  BCJ
		 filter.   For example, if there are similar or even identical
		 executables then filtering will likely make  the  files  less
		 similar  and thus compression is worse.  The contents of non-
		 executable files in the same  archive	can  matter  too.   In
		 practice  one has to try with and without a BCJ filter to see
		 which is better in each situation.

	      Different instruction sets have different	 alignment:  the  exe‐
	      cutable  file must be aligned to a multiple of this value in the
	      input data to make the filter work.

		     tab(;); l n l l n l.  Filter;Alignment;Notes x86;1;32-bit
		     or	  64-bit  x86  ARM;4;  ARM-Thumb;2;  ARM64;4;4096-byte
		     alignment is best PowerPC;4;Big endian only IA-64;16;Ita‐
		     nium SPARC;4; RISC-V;2;

	      Since  the  BCJ-filtered	data is usually compressed with LZMA2,
	      the compression ratio may be improved slightly if the LZMA2  op‐
	      tions are set to match the alignment of the selected BCJ filter.
	      Examples:

	      •	 IA-64 filter has 16-byte alignment so pb=4,lp=4,lc=0 is  good
		 with LZMA2 (2^4=16).

	      •	 RISC-V	 code  has  2-byte  or	4-byte	alignment depending on
		 whether the file contains 16-bit compressed instructions (the
		 C   extension).    When   16-bit   instructions   are	 used,
		 pb=2,lp=1,lc=3 or pb=1,lp=1,lc=3 is good.   When  16-bit  in‐
		 structions aren't present, pb=2,lp=2,lc=2 is the best.	 read‐
		 elf -h can be used to check if "RVC" appears on  the  "Flags"
		 line.

	      •	 ARM64 is always 4-byte aligned so pb=2,lp=2,lc=2 is the best.

	      •	 The  x86  filter is an exception.  It's usually good to stick
		 to LZMA2's defaults (pb=2,lp=0,lc=3) when compressing x86 ex‐
		 ecutables.

	      All BCJ filters support the same options:

	      start=offset
		     Specify the start offset that is used when converting be‐
		     tween relative and absolute addresses.  The  offset  must
		     be a multiple of the alignment of the filter (see the ta‐
		     ble above).  The default is zero.	In practice,  the  de‐
		     fault is good; specifying a custom offset is almost never
		     useful.

       --delta[=options]
	      Add the Delta filter to the filter chain.	 The Delta filter  can
	      be only used as a non-last filter in the filter chain.

	      Currently	 only simple byte-wise delta calculation is supported.
	      It can be useful when  compressing,  for	example,  uncompressed
	      bitmap  images or uncompressed PCM audio.	 However, special pur‐
	      pose algorithms may give significantly better results than Delta
	      +	 LZMA2.	  This is true especially with audio, which compresses
	      faster and better, for example, with flac(1).

	      Supported options:

	      dist=distance
		     Specify the distance of the delta calculation  in	bytes.
		     distance must be 1–256.  The default is 1.

		     For example, with dist=2 and eight-byte input A1 B1 A2 B3
		     A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

   Other options
       -q, --quiet
	      Suppress warnings and notices.  Specify this twice  to  suppress
	      errors too.  This option has no effect on the exit status.  That
	      is, even if a warning was suppressed, the exit status  to	 indi‐
	      cate a warning is still used.

       -v, --verbose
	      Be  verbose.   If	 standard error is connected to a terminal, xz
	      will display a progress indicator.  Specifying  --verbose	 twice
	      will give even more verbose output.

	      The progress indicator shows the following information:

	      •	 Completion  percentage is shown if the size of the input file
		 is known.  That is, the percentage cannot be shown in pipes.

	      •	 Amount of compressed data produced (compressing) or  consumed
		 (decompressing).

	      •	 Amount	 of  uncompressed  data consumed (compressing) or pro‐
		 duced (decompressing).

	      •	 Compression ratio, which is calculated by dividing the amount
		 of  compressed	 data processed so far by the amount of uncom‐
		 pressed data processed so far.

	      •	 Compression or decompression speed.  This is measured as  the
		 amount	 of  uncompressed  data consumed (compression) or pro‐
		 duced (decompression) per second.  It is shown	 after	a  few
		 seconds have passed since xz started processing the file.

	      •	 Elapsed time in the format M:SS or H:MM:SS.

	      •	 Estimated  remaining  time is shown only when the size of the
		 input file is known and a  couple  of	seconds	 have  already
		 passed	 since	xz  started  processing the file.  The time is
		 shown in a less precise format which never  has  any  colons,
		 for example, 2 min 30 s.

	      When  standard  error  is not a terminal, --verbose will make xz
	      print the filename, compressed size, uncompressed size, compres‐
	      sion  ratio,  and	 possibly also the speed and elapsed time on a
	      single line to standard error after compressing or decompressing
	      the file.	 The speed and elapsed time are included only when the
	      operation took at least a few seconds.  If the operation	didn't
	      finish,  for example, due to user interruption, also the comple‐
	      tion percentage is printed if the size  of  the  input  file  is
	      known.

       -Q, --no-warn
	      Don't set the exit status to 2 even if a condition worth a warn‐
	      ing was detected.	 This  option  doesn't	affect	the  verbosity
	      level,  thus  both  --quiet and --no-warn have to be used to not
	      display warnings and to not alter the exit status.

       --robot
	      Print messages in a machine-parsable format.  This  is  intended
	      to  ease	writing	 frontends  that want to use xz instead of li‐
	      blzma, which may be the case with various scripts.   The	output
	      with  this  option  enabled  is meant to be stable across xz re‐
	      leases.  See the section ROBOT MODE for details.

       --info-memory
	      Display, in human-readable  format,  how	much  physical	memory
	      (RAM)  and  how  many processor threads xz thinks the system has
	      and the memory usage limits for compression  and	decompression,
	      and exit successfully.

       -h, --help
	      Display  a  help	message	 describing the most commonly used op‐
	      tions, and exit successfully.

       -H, --long-help
	      Display a help message describing all features of xz,  and  exit
	      successfully

       -V, --version
	      Display  the  version number of xz and liblzma in human readable
	      format.  To get machine-parsable output, specify --robot	before
	      --version.

ROBOT MODE
       The robot mode is activated with the --robot option.  It makes the out‐
       put of xz easier to parse by other programs.  Currently --robot is sup‐
       ported  only  together  with --list, --filters-help, --info-memory, and
       --version.  It will be supported for compression and  decompression  in
       the future.

   List mode
       xz --robot --list uses tab-separated output.  The first column of every
       line has a string that indicates the type of the information  found  on
       that line:

       name   This is always the first line when starting to list a file.  The
	      second column on the line is the filename.

       file   This line contains overall information about the .xz file.  This
	      line is always printed after the name line.

       stream This line type is used only when --verbose was specified.	 There
	      are as many stream lines as there are streams in the .xz file.

       block  This line type is used only when --verbose was specified.	 There
	      are  as  many  block  lines as there are blocks in the .xz file.
	      The block lines are shown after all the stream lines;  different
	      line types are not interleaved.

       summary
	      This  line type is used only when --verbose was specified twice.
	      This line is printed after all block lines.  Like the file line,
	      the  summary  line  contains  overall  information about the .xz
	      file.

       totals This line is always the very last line of the list  output.   It
	      shows the total counts and sizes.

       The columns of the file lines:
	      2.  Number of streams in the file
	      3.  Total number of blocks in the stream(s)
	      4.  Compressed size of the file
	      5.  Uncompressed size of the file
	      6.  Compression  ratio,  for  example,  0.123.  If ratio is over
		  9.999, three dashes (---) are displayed instead of  the  ra‐
		  tio.
	      7.  Comma-separated  list of integrity check names.  The follow‐
		  ing strings are used for the known check types: None, CRC32,
		  CRC64,  and  SHA-256.	 For unknown check types, Unknown-N is
		  used, where N is the Check ID as a decimal  number  (one  or
		  two digits).
	      8.  Total size of stream padding in the file

       The columns of the stream lines:
	      2.  Stream number (the first stream is 1)
	      3.  Number of blocks in the stream
	      4.  Compressed start offset
	      5.  Uncompressed start offset
	      6.  Compressed size (does not include stream padding)
	      7.  Uncompressed size
	      8.  Compression ratio
	      9.  Name of the integrity check
	      10. Size of stream padding

       The columns of the block lines:
	      2.  Number of the stream containing this block
	      3.  Block	 number	 relative  to the beginning of the stream (the
		  first block is 1)
	      4.  Block number relative to the beginning of the file
	      5.  Compressed start offset relative to  the  beginning  of  the
		  file
	      6.  Uncompressed	start  offset relative to the beginning of the
		  file
	      7.  Total compressed size of the block (includes headers)
	      8.  Uncompressed size
	      9.  Compression ratio
	      10. Name of the integrity check

       If --verbose was specified twice, additional columns  are  included  on
       the  block lines.  These are not displayed with a single --verbose, be‐
       cause getting this information requires many  seeks  and	 can  thus  be
       slow:
	      11. Value of the integrity check in hexadecimal
	      12. Block header size
	      13. Block	 flags:	 c  indicates that compressed size is present,
		  and u indicates that uncompressed size is present.   If  the
		  flag	is  not	 set,  a dash (-) is shown instead to keep the
		  string length fixed.	New flags may be added to the  end  of
		  the string in the future.
	      14. Size	of  the	 actual compressed data in the block (this ex‐
		  cludes the block header, block padding, and check fields)
	      15. Amount of memory (in	bytes)	required  to  decompress  this
		  block with this xz version
	      16. Filter  chain.   Note	 that most of the options used at com‐
		  pression time cannot be known, because only the options that
		  are needed for decompression are stored in the .xz headers.

       The columns of the summary lines:
	      2.  Amount of memory (in bytes) required to decompress this file
		  with this xz version
	      3.  yes or no indicating if all block  headers  have  both  com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      4.  Minimum xz version required to decompress the file

       The columns of the totals line:
	      2.  Number of streams
	      3.  Number of blocks
	      4.  Compressed size
	      5.  Uncompressed size
	      6.  Average compression ratio
	      7.  Comma-separated  list	 of  integrity	check  names that were
		  present in the files
	      8.  Stream padding size
	      9.  Number of files.  This is here to keep the order of the ear‐
		  lier columns the same as on file lines.

       If  --verbose  was  specified twice, additional columns are included on
       the totals line:
	      10. Maximum amount of memory (in bytes) required	to  decompress
		  the files with this xz version
	      11. yes  or  no  indicating  if all block headers have both com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      12. Minimum xz version required to decompress the file

       Future versions may add new line types and new columns can be added  to
       the existing line types, but the existing columns won't be changed.

   Filters help
       xz --robot --filters-help prints the supported filters in the following
       format:

       filter:option=<value>,option=<value>...

       filter Name of the filter

       option Name of a filter specific option

       value  Numeric value ranges appear as <min-max>.	 String value  choices
	      are shown within < > and separated by a | character.

       Each filter is printed on its own line.

   Memory limit information
       xz  --robot  --info-memory prints a single line with multiple tab-sepa‐
       rated columns:

       1.  Total amount of physical memory (RAM) in bytes.

       2.  Memory usage limit for compression in bytes	(--memlimit-compress).
	   A  special  value of 0 indicates the default setting which for sin‐
	   gle-threaded mode is the same as no limit.

       3.  Memory usage limit for decompression	 in  bytes  (--memlimit-decom‐
	   press).   A	special value of 0 indicates the default setting which
	   for single-threaded mode is the same as no limit.

       4.  Since xz 5.3.4alpha: Memory usage for multi-threaded	 decompression
	   in  bytes (--memlimit-mt-decompress).  This is never zero because a
	   system-specific default value shown in the column 5 is used	if  no
	   limit  has  been  specified explicitly.  This is also never greater
	   than the value in the column 3 even if  a  larger  value  has  been
	   specified with --memlimit-mt-decompress.

       5.  Since  xz  5.3.4alpha: A system-specific default memory usage limit
	   that is used to limit the number of threads when  compressing  with
	   an  automatic  number  of threads (--threads=0) and no memory usage
	   limit has been specified (--memlimit-compress).  This is also  used
	   as the default value for --memlimit-mt-decompress.

       6.  Since xz 5.3.4alpha: Number of available processor threads.

       In  the	future,	 the  output of xz --robot --info-memory may have more
       columns, but never more than a single line.

   Version
       xz --robot --version prints the version number of xz and liblzma in the
       following format:

       XZ_VERSION=XYYYZZZS
       LIBLZMA_VERSION=XYYYZZZS

       X      Major version.

       YYY    Minor  version.  Even numbers are stable.	 Odd numbers are alpha
	      or beta versions.

       ZZZ    Patch level for stable releases or just a counter	 for  develop‐
	      ment releases.

       S      Stability.  0 is alpha, 1 is beta, and 2 is stable.  S should be
	      always 2 when YYY is even.

       XYYYZZZS are the same on both lines if xz and liblzma are from the same
       XZ Utils release.

       Examples: 4.999.9beta is 49990091 and 5.0.0 is 50000002.

EXIT STATUS
       0      All is good.

       1      An error occurred.

       2      Something	 worth	a  warning  occurred, but no actual errors oc‐
	      curred.

       Notices (not warnings or errors) printed on standard error don't affect
       the exit status.

ENVIRONMENT
       xz  parses  space-separated lists of options from the environment vari‐
       ables XZ_DEFAULTS and XZ_OPT, in this order, before parsing the options
       from  the command line.	Note that only options are parsed from the en‐
       vironment variables; all non-options are silently ignored.  Parsing  is
       done  with getopt_long(3) which is used also for the command line argu‐
       ments.

       XZ_DEFAULTS
	      User-specific or system-wide default options.  Typically this is
	      set in a shell initialization script to enable xz's memory usage
	      limiter by default.  Excluding shell initialization scripts  and
	      similar  special	cases,	scripts must never set or unset XZ_DE‐
	      FAULTS.

       XZ_OPT This is for passing options to xz when it is not possible to set
	      the  options  directly on the xz command line.  This is the case
	      when xz is run by a script or tool, for example, GNU tar(1):

		     XZ_OPT=-2v tar caf foo.tar.xz foo

	      Scripts may use XZ_OPT, for example, to set script-specific  de‐
	      fault  compression  options.   It	 is still recommended to allow
	      users to override XZ_OPT if that is reasonable.  For example, in
	      sh(1) scripts one may use something like this:

		     XZ_OPT=${XZ_OPT-"-7e"}
		     export XZ_OPT

LZMA UTILS COMPATIBILITY
       The  command  line  syntax of xz is practically a superset of lzma, un‐
       lzma, and lzcat as found from LZMA Utils 4.32.x.	 In most cases, it  is
       possible	 to replace LZMA Utils with XZ Utils without breaking existing
       scripts.	 There are some incompatibilities though, which may  sometimes
       cause problems.

   Compression preset levels
       The  numbering  of the compression level presets is not identical in xz
       and LZMA Utils.	The most important difference is how dictionary	 sizes
       are  mapped  to different presets.  Dictionary size is roughly equal to
       the decompressor memory usage.

	      tab(;); c c c c n n.  Level;xz;LZMA Utils	 -0;256	 KiB;N/A  -1;1
	      MiB;64  KiB  -2;2 MiB;1 MiB -3;4 MiB;512 KiB -4;4 MiB;1 MiB -5;8
	      MiB;2 MiB -6;8 MiB;4 MiB -7;16 MiB;8 MiB -8;32 MiB;16 MiB	 -9;64
	      MiB;32 MiB

       The dictionary size differences affect the compressor memory usage too,
       but there are some other differences between LZMA Utils and  XZ	Utils,
       which make the difference even bigger:

	      tab(;);  c  c  c c n n.  Level;xz;LZMA Utils 4.32.x -0;3 MiB;N/A
	      -1;9 MiB;2 MiB -2;17 MiB;12 MiB -3;32 MiB;12  MiB	 -4;48	MiB;16
	      MiB  -5;94  MiB;26 MiB -6;94 MiB;45 MiB -7;186 MiB;83 MiB -8;370
	      MiB;159 MiB -9;674 MiB;311 MiB

       The default preset level in LZMA Utils is -7 while in XZ	 Utils	it  is
       -6, so both use an 8 MiB dictionary by default.

   Streamed vs. non-streamed .lzma files
       The  uncompressed  size	of the file can be stored in the .lzma header.
       LZMA Utils does that when compressing regular files.   The  alternative
       is  to  mark  that  uncompressed size is unknown and use end-of-payload
       marker to indicate where the decompressor should stop.  LZMA Utils uses
       this  method when uncompressed size isn't known, which is the case, for
       example, in pipes.

       xz supports decompressing .lzma files with  or  without	end-of-payload
       marker,	but  all  .lzma	 files	created	 by xz will use end-of-payload
       marker and have uncompressed  size  marked  as  unknown	in  the	 .lzma
       header.	 This may be a problem in some uncommon situations.  For exam‐
       ple, a .lzma decompressor in an embedded device might  work  only  with
       files  that have known uncompressed size.  If you hit this problem, you
       need to use LZMA Utils or LZMA SDK to create .lzma files with known un‐
       compressed size.

   Unsupported .lzma files
       The .lzma format allows lc values up to 8, and lp values up to 4.  LZMA
       Utils can decompress files with any lc and lp, but always creates files
       with  lc=3  and	lp=0.  Creating files with other lc and lp is possible
       with xz and with LZMA SDK.

       The implementation of the LZMA1 filter in liblzma requires that the sum
       of  lc  and lp must not exceed 4.  Thus, .lzma files, which exceed this
       limitation, cannot be decompressed with xz.

       LZMA Utils creates only .lzma files which have a dictionary size of 2^n
       (a power of 2) but accepts files with any dictionary size.  liblzma ac‐
       cepts only .lzma files which have a dictionary size of  2^n  or	2^n  +
       2^(n-1).	  This	is  to	decrease  false positives when detecting .lzma
       files.

       These limitations shouldn't be a problem in practice, since practically
       all  .lzma  files  have been compressed with settings that liblzma will
       accept.

   Trailing garbage
       When decompressing, LZMA Utils silently	ignore	everything  after  the
       first  .lzma  stream.   In  most	 situations, this is a bug.  This also
       means that LZMA Utils don't support  decompressing  concatenated	 .lzma
       files.

       If  there  is  data left after the first .lzma stream, xz considers the
       file to be corrupt unless --single-stream was used.  This may break ob‐
       scure scripts which have assumed that trailing garbage is ignored.

NOTES
   Compressed output may vary
       The  exact  compressed output produced from the same uncompressed input
       file may vary between XZ Utils versions even if compression options are
       identical.  This is because the encoder can be improved (faster or bet‐
       ter compression) without affecting the file  format.   The  output  can
       vary  even  between  different  builds of the same XZ Utils version, if
       different build options are used.

       The above means that once --rsyncable has been implemented, the result‐
       ing  files won't necessarily be rsyncable unless both old and new files
       have been compressed with the same xz version.	This  problem  can  be
       fixed if a part of the encoder implementation is frozen to keep rsynca‐
       ble output stable across xz versions.

   Embedded .xz decompressors
       Embedded .xz decompressor implementations like XZ Embedded don't neces‐
       sarily support files created with integrity check types other than none
       and  crc32.   Since  the	 default  is  --check=crc64,  you   must   use
       --check=none or --check=crc32 when creating files for embedded systems.

       Outside	embedded systems, all .xz format decompressors support all the
       check types, or at least are able to decompress the file without	 veri‐
       fying the integrity check if the particular check is not supported.

       XZ  Embedded supports BCJ filters, but only with the default start off‐
       set.

EXAMPLES
   Basics
       Compress the file foo into foo.xz using the default  compression	 level
       (-6), and remove foo if compression is successful:

	      xz foo

       Decompress  bar.xz  into bar and don't remove bar.xz even if decompres‐
       sion is successful:

	      xz -dk bar.xz

       Create baz.tar.xz with the preset -4e (-4 --extreme), which  is	slower
       than  the  default -6, but needs less memory for compression and decom‐
       pression (48 MiB and 5 MiB, respectively):

	      tar cf - baz | xz -4e > baz.tar.xz

       A mix of compressed and uncompressed files can be decompressed to stan‐
       dard output with a single command:

	      xz -dcf a.txt b.txt.xz c.txt d.txt.lzma > abcd.txt

   Parallel compression of many files
       On  GNU	and *BSD, find(1) and xargs(1) can be used to parallelize com‐
       pression of many files:

	      find . -type f \! -name '*.xz' -print0 \
		  | xargs -0r -P4 -n16 xz -T1

       The -P option to xargs(1) sets the number  of  parallel	xz  processes.
       The best value for the -n option depends on how many files there are to
       be compressed.  If there are only a couple of files, the	 value	should
       probably be 1; with tens of thousands of files, 100 or even more may be
       appropriate to reduce the number of xz  processes  that	xargs(1)  will
       eventually create.

       The option -T1 for xz is there to force it to single-threaded mode, be‐
       cause xargs(1) is used to control the amount of parallelization.

   Robot mode
       Calculate how many bytes have been saved	 in  total  after  compressing
       multiple files:

	      xz --robot --list *.xz | awk '/^totals/{print $5-$4}'

       A  script may want to know that it is using new enough xz.  The follow‐
       ing sh(1) script checks that the version number of the xz  tool	is  at
       least  5.0.0.   This method is compatible with old beta versions, which
       didn't support the --robot option:

	      if ! eval "$(xz --robot --version 2> /dev/null)" ||
		      [ "$XZ_VERSION" -lt 50000002 ]; then
		  echo "Your xz is too old."
	      fi
	      unset XZ_VERSION LIBLZMA_VERSION

       Set a memory usage limit for decompression using XZ_OPT, but if a limit
       has already been set, don't increase it:

	      NEWLIM=$((123 << 20))  # 123 MiB
	      OLDLIM=$(xz --robot --info-memory | cut -f3)
	      if [ $OLDLIM -eq 0 -o $OLDLIM -gt $NEWLIM ]; then
		  XZ_OPT="$XZ_OPT --memlimit-decompress=$NEWLIM"
		  export XZ_OPT
	      fi

   Custom compressor filter chains
       The  simplest  use for custom filter chains is customizing a LZMA2 pre‐
       set.  This can be useful, because the presets cover only	 a  subset  of
       the potentially useful combinations of compression settings.

       The  CompCPU columns of the tables from the descriptions of the options
       -0 ... -9 and --extreme are  useful  when  customizing  LZMA2  presets.
       Here are the relevant parts collected from those two tables:

	      tab(;);  c  c n n.  Preset;CompCPU -0;0 -1;1 -2;2 -3;3 -4;4 -5;5
	      -6;6 -5e;7 -6e;8

       If you know that a file requires somewhat big dictionary (for  example,
       32 MiB)	to  compress well, but you want to compress it quicker than xz
       -8 would do, a preset with a low CompCPU value (for example, 1) can  be
       modified to use a bigger dictionary:

	      xz --lzma2=preset=1,dict=32MiB foo.tar

       With  certain  files,  the above command may be faster than xz -6 while
       compressing significantly better.  However, it must be emphasized  that
       only some files benefit from a big dictionary while keeping the CompCPU
       value low.  The most obvious situation, where a big dictionary can help
       a  lot,	is  an archive containing very similar files of at least a few
       megabytes each.	The dictionary size has	 to  be	 significantly	bigger
       than  any  individual file to allow LZMA2 to take full advantage of the
       similarities between consecutive files.

       If very high compressor and decompressor memory usage is fine, and  the
       file  being compressed is at least several hundred megabytes, it may be
       useful to use an even bigger dictionary than the	 64  MiB  that	xz  -9
       would use:

	      xz -vv --lzma2=dict=192MiB big_foo.tar

       Using -vv (--verbose --verbose) like in the above example can be useful
       to see the memory requirements of the compressor and decompressor.  Re‐
       member that using a dictionary bigger than the size of the uncompressed
       file is waste of memory, so the above command isn't  useful  for	 small
       files.

       Sometimes  the  compression  time  doesn't matter, but the decompressor
       memory usage has to be kept low, for example, to make  it  possible  to
       decompress  the file on an embedded system.  The following command uses
       -6e (-6 --extreme) as a base and sets the dictionary  to	 only  64 KiB.
       The  resulting  file  can  be decompressed with XZ Embedded (that's why
       there is --check=crc32) using about 100 KiB of memory.

	      xz --check=crc32 --lzma2=preset=6e,dict=64KiB foo

       If you want to squeeze out as many bytes	 as  possible,	adjusting  the
       number  of  literal  context bits (lc) and number of position bits (pb)
       can sometimes help.  Adjusting the number of literal position bits (lp)
       might help too, but usually lc and pb are more important.  For example,
       a source code archive contains mostly US-ASCII text, so something  like
       the following might give slightly (like 0.1 %) smaller file than xz -6e
       (try also without lc=4):

	      xz --lzma2=preset=6e,pb=0,lc=4 source_code.tar

       Using another filter together with LZMA2 can improve  compression  with
       certain file types.  For example, to compress a x86-32 or x86-64 shared
       library using the x86 BCJ filter:

	      xz --x86 --lzma2 libfoo.so

       Note that the order of the filter options is significant.  If --x86  is
       specified after --lzma2, xz will give an error, because there cannot be
       any filter after LZMA2, and also because the x86 BCJ filter  cannot  be
       used as the last filter in the chain.

       The  Delta filter together with LZMA2 can give good results with bitmap
       images.	It should usually beat PNG, which has a few more advanced fil‐
       ters than simple delta but uses Deflate for the actual compression.

       The  image  has to be saved in uncompressed format, for example, as un‐
       compressed TIFF.	 The distance parameter of the Delta filter is set  to
       match  the number of bytes per pixel in the image.  For example, 24-bit
       RGB bitmap needs dist=3, and it is also good to pass pb=0 to  LZMA2  to
       accommodate the three-byte alignment:

	      xz --delta=dist=3 --lzma2=pb=0 foo.tiff

       If  multiple  images  have been put into a single archive (for example,
       .tar), the Delta filter will work on that too as	 long  as  all	images
       have the same number of bytes per pixel.

SEE ALSO
       xzdec(1),   xzdiff(1),	xzgrep(1),   xzless(1),	  xzmore(1),  gzip(1),
       bzip2(1), 7z(1)

       XZ Utils: <https://tukaani.org/xz/>
       XZ Embedded: <https://tukaani.org/xz/embedded.html>
       LZMA SDK: <https://7-zip.org/sdk.html>



Tukaani				  2024-12-30				 XZ(1)

XZMORE(1)			   XZ Utils			     XZMORE(1)



NAME
       xzmore, lzmore - view xz or lzma compressed (text) files

SYNOPSIS
       xzmore [file...]
       lzmore [file...]

DESCRIPTION
       xzmore displays text from compressed files to a terminal using more(1).
       Files supported by xz(1) are decompressed; other files are  assumed  to
       be  in  uncompressed form already.  If no files are given, xzmore reads
       from standard input.  See the more(1) manual for the keyboard commands.

       Note that scrolling backwards might not be possible  depending  on  the
       implementation  of more(1).  This is because xzmore uses a pipe to pass
       the decompressed data to more(1).  xzless(1) uses  less(1)  which  pro‐
       vides more advanced features.

       The  command  lzmore  is	 provided for backward compatibility with LZMA
       Utils.

ENVIRONMENT
       PAGER  If PAGER is set, its value is  used  as  the  pager  instead  of
	      more(1).

SEE ALSO
       more(1), xz(1), xzless(1), zmore(1)



Tukaani				  2024-02-12			     XZMORE(1)

XZ(1)				   XZ Utils				 XZ(1)



NAME
       xz,  unxz,  xzcat, lzma, unlzma, lzcat - Compress or decompress .xz and
       .lzma files

SYNOPSIS
       xz [option...]  [file...]

COMMAND ALIASES
       unxz is equivalent to xz --decompress.
       xzcat is equivalent to xz --decompress --stdout.
       lzma is equivalent to xz --format=lzma.
       unlzma is equivalent to xz --format=lzma --decompress.
       lzcat is equivalent to xz --format=lzma --decompress --stdout.

       When writing scripts that need to decompress files, it  is  recommended
       to  always use the name xz with appropriate arguments (xz -d or xz -dc)
       instead of the names unxz and xzcat.

DESCRIPTION
       xz is a general-purpose data compression tool with command line	syntax
       similar	to  gzip(1)  and  bzip2(1).  The native file format is the .xz
       format, but the legacy .lzma format used by LZMA	 Utils	and  raw  com‐
       pressed	streams	 with  no container format headers are also supported.
       In addition, decompression of the .lz format used by lzip is supported.

       xz compresses or decompresses each file according to the selected oper‐
       ation mode.  If no files are given or file is -, xz reads from standard
       input and writes the processed data to standard output.	xz will refuse
       (display	 an error and skip the file) to write compressed data to stan‐
       dard output if it is a terminal.	 Similarly, xz	will  refuse  to  read
       compressed data from standard input if it is a terminal.

       Unless  --stdout	 is specified, files other than - are written to a new
       file whose name is derived from the source file name:

       •  When compressing, the suffix of  the	target	file  format  (.xz  or
	  .lzma)  is  appended	to the source filename to get the target file‐
	  name.

       •  When decompressing, the .xz, .lzma, or .lz suffix  is	 removed  from
	  the  filename	 to  get  the target filename.	xz also recognizes the
	  suffixes .txz and .tlz, and replaces them with the .tar suffix.

       If the target file already exists, an error is displayed and  the  file
       is skipped.

       Unless  writing	to standard output, xz will display a warning and skip
       the file if any of the following applies:

       •  File is not a regular file.  Symbolic links are  not	followed,  and
	  thus they are not considered to be regular files.

       •  File has more than one hard link.

       •  File has setuid, setgid, or sticky bit set.

       •  The  operation  mode	is  set to compress and the file already has a
	  suffix of the target file format (.xz or .txz	 when  compressing  to
	  the .xz format, and .lzma or .tlz when compressing to the .lzma for‐
	  mat).

       •  The operation mode is set to decompress and the file doesn't have  a
	  suffix of any of the supported file formats (.xz, .txz, .lzma, .tlz,
	  or .lz).

       After successfully compressing or decompressing the file, xz copies the
       owner,  group, permissions, access time, and modification time from the
       source file to the target file.	If copying the group fails,  the  per‐
       missions are modified so that the target file doesn't become accessible
       to users who didn't have permission to  access  the  source  file.   xz
       doesn't support copying other metadata like access control lists or ex‐
       tended attributes yet.

       Once the target file has been successfully closed, the source  file  is
       removed	unless --keep was specified.  The source file is never removed
       if the output is written to standard output or if an error occurs.

       Sending SIGINFO or SIGUSR1 to the xz process makes  it  print  progress
       information  to	standard  error.  This has only limited use since when
       standard error is a terminal, using --verbose will display an automati‐
       cally updating progress indicator.

   Memory usage
       The  memory  usage of xz varies from a few hundred kilobytes to several
       gigabytes depending on the compression  settings.   The	settings  used
       when compressing a file determine the memory requirements of the decom‐
       pressor.	 Typically the decompressor needs 5 % to 20 % of the amount of
       memory that the compressor needed when creating the file.  For example,
       decompressing a file created with xz -9 currently  requires  65 MiB  of
       memory.	 Still,	 it is possible to have .xz files that require several
       gigabytes of memory to decompress.

       Especially users of older systems may  find  the	 possibility  of  very
       large  memory  usage  annoying.	To prevent uncomfortable surprises, xz
       has a built-in memory usage limiter,  which  is	disabled  by  default.
       While  some operating systems provide ways to limit the memory usage of
       processes, relying on it wasn't deemed to be flexible enough (for exam‐
       ple, using ulimit(1) to limit virtual memory tends to cripple mmap(2)).

       The  memory  usage  limiter can be enabled with the command line option
       --memlimit=limit.  Often it is more convenient to enable the limiter by
       default	by  setting the environment variable XZ_DEFAULTS, for example,
       XZ_DEFAULTS=--memlimit=150MiB.  It is possible to set the limits	 sepa‐
       rately  for  compression	 and  decompression  by	 using --memlimit-com‐
       press=limit and --memlimit-decompress=limit.  Using these  two  options
       outside	XZ_DEFAULTS is rarely useful because a single run of xz cannot
       do both compression  and	 decompression	and  --memlimit=limit  (or  -M
       limit) is shorter to type on the command line.

       If  the specified memory usage limit is exceeded when decompressing, xz
       will display an error and decompressing the file	 will  fail.   If  the
       limit  is  exceeded when compressing, xz will try to scale the settings
       down so that the limit is no longer exceeded (except when using	--for‐
       mat=raw	or --no-adjust).  This way the operation won't fail unless the
       limit is very small.  The scaling of the settings is done in steps that
       don't match the compression level presets, for example, if the limit is
       only slightly less than the amount required for	xz  -9,	 the  settings
       will be scaled down only a little, not all the way down to xz -8.

   Concatenation and padding with .xz files
       It is possible to concatenate .xz files as is.  xz will decompress such
       files as if they were a single .xz file.

       It is possible to insert padding between the concatenated parts or  af‐
       ter the last part.  The padding must consist of null bytes and the size
       of the padding must be a multiple of four bytes.	 This can  be  useful,
       for  example,  if the .xz file is stored on a medium that measures file
       sizes in 512-byte blocks.

       Concatenation and padding are not  allowed  with	 .lzma	files  or  raw
       streams.

OPTIONS
   Integer suffixes and special values
       In  most places where an integer argument is expected, an optional suf‐
       fix is supported to easily indicate large integers.  There must	be  no
       space between the integer and the suffix.

       KiB    Multiply	the integer by 1,024 (2^10).  Ki, k, kB, K, and KB are
	      accepted as synonyms for KiB.

       MiB    Multiply the integer by 1,048,576 (2^20).	 Mi, m, M, and MB  are
	      accepted as synonyms for MiB.

       GiB    Multiply	the integer by 1,073,741,824 (2^30).  Gi, g, G, and GB
	      are accepted as synonyms for GiB.

       The special value max can be used to indicate the maximum integer value
       supported by the option.

   Operation mode
       If  multiple  operation	mode options are given, the last one takes ef‐
       fect.

       -z, --compress
	      Compress.	 This is the default operation mode when no  operation
	      mode  option is specified and no other operation mode is implied
	      from the command name (for example, unxz implies --decompress).

	      After successful compression, the source file is removed	unless
	      writing to standard output or --keep was specified.

       -d, --decompress, --uncompress
	      Decompress.   After successful decompression, the source file is
	      removed unless writing to standard output or --keep  was	speci‐
	      fied.

       -t, --test
	      Test  the integrity of compressed files.	This option is equiva‐
	      lent to --decompress --stdout except that the decompressed  data
	      is  discarded  instead  of being written to standard output.  No
	      files are created or removed.

       -l, --list
	      Print information about compressed files.	 No uncompressed  out‐
	      put  is  produced, and no files are created or removed.  In list
	      mode, the program cannot read the compressed data from  standard
	      input or from other unseekable sources.

	      The  default  listing  shows  basic information about files, one
	      file per line.  To get more detailed information, use  also  the
	      --verbose	 option.   For	even  more  information, use --verbose
	      twice, but note that this may be slow, because getting  all  the
	      extra  information  requires  many  seeks.  The width of verbose
	      output exceeds 80 characters, so piping the output to, for exam‐
	      ple,  less -S  may  be  convenient  if  the  terminal isn't wide
	      enough.

	      The exact output may vary between xz versions and different  lo‐
	      cales.   For  machine-readable  output, --robot --list should be
	      used.

   Operation modifiers
       -k, --keep
	      Don't delete the input files.

	      Since xz 5.2.6, this option also makes xz compress or decompress
	      even if the input is a symbolic link to a regular file, has more
	      than one hard link, or has the setuid,  setgid,  or  sticky  bit
	      set.   The setuid, setgid, and sticky bits are not copied to the
	      target file.  In	earlier	 versions  this	 was  only  done  with
	      --force.

       -f, --force
	      This option has several effects:

	      •	 If the target file already exists, delete it before compress‐
		 ing or decompressing.

	      •	 Compress or decompress even if the input is a	symbolic  link
		 to  a	regular	 file, has more than one hard link, or has the
		 setuid, setgid, or sticky bit set.  The setuid,  setgid,  and
		 sticky bits are not copied to the target file.

	      •	 When  used with --decompress --stdout and xz cannot recognize
		 the type of the source file, copy the source file  as	is  to
		 standard  output.   This allows xzcat --force to be used like
		 cat(1) for files that have not been compressed with xz.  Note
		 that in future, xz might support new compressed file formats,
		 which may make xz decompress more types of files  instead  of
		 copying  them	as is to standard output.  --format=format can
		 be used to restrict xz to decompress only a single file  for‐
		 mat.

       -c, --stdout, --to-stdout
	      Write the compressed or decompressed data to standard output in‐
	      stead of a file.	This implies --keep.

       --single-stream
	      Decompress only the first .xz stream, and silently ignore possi‐
	      ble  remaining  input  data following the stream.	 Normally such
	      trailing garbage makes xz display an error.

	      xz never decompresses more than one stream from .lzma  files  or
	      raw  streams, but this option still makes xz ignore the possible
	      trailing data after the .lzma file or raw stream.

	      This option has no effect if the operation mode is not  --decom‐
	      press or --test.

       --no-sparse
	      Disable  creation of sparse files.  By default, if decompressing
	      into a regular file, xz tries to make the file sparse if the de‐
	      compressed  data	contains  long	sequences of binary zeros.  It
	      also works when writing to standard output as long  as  standard
	      output  is  connected  to	 a regular file and certain additional
	      conditions are met to make it safe.  Creating sparse  files  may
	      save  disk  space and speed up the decompression by reducing the
	      amount of disk I/O.

       -S .suf, --suffix=.suf
	      When compressing, use .suf as the suffix for the target file in‐
	      stead  of	 .xz  or .lzma.	 If not writing to standard output and
	      the source file already has the suffix .suf, a warning  is  dis‐
	      played and the file is skipped.

	      When  decompressing, recognize files with the suffix .suf in ad‐
	      dition to files with the .xz, .txz, .lzma, .tlz, or .lz  suffix.
	      If the source file has the suffix .suf, the suffix is removed to
	      get the target filename.

	      When compressing or decompressing	 raw  streams  (--format=raw),
	      the  suffix  must always be specified unless writing to standard
	      output, because there is no default suffix for raw streams.

       --files[=file]
	      Read the filenames to process from file;	if  file  is  omitted,
	      filenames	 are read from standard input.	Filenames must be ter‐
	      minated with the newline character.  A dash (-) is  taken	 as  a
	      regular  filename; it doesn't mean standard input.  If filenames
	      are given also as command line arguments, they are processed be‐
	      fore the filenames read from file.

       --files0[=file]
	      This  is	identical  to --files[=file] except that each filename
	      must be terminated with the null character.

   Basic file format and compression options
       -F format, --format=format
	      Specify the file format to compress or decompress:

	      auto   This is the default.  When compressing, auto  is  equiva‐
		     lent  to xz.  When decompressing, the format of the input
		     file is automatically detected.  Note  that  raw  streams
		     (created with --format=raw) cannot be auto-detected.

	      xz     Compress to the .xz file format, or accept only .xz files
		     when decompressing.

	      lzma, alone
		     Compress to the legacy .lzma file format, or accept  only
		     .lzma  files  when	 decompressing.	  The alternative name
		     alone is provided for backwards compatibility  with  LZMA
		     Utils.

	      lzip   Accept only .lz files when decompressing.	Compression is
		     not supported.

		     The .lz format version 0 and the unextended version 1 are
		     supported.	 Version 0 files were produced by lzip 1.3 and
		     older.  Such files aren't common but may  be  found  from
		     file  archives  as a few source packages were released in
		     this format.  People might have  old  personal  files  in
		     this  format  too.	  Decompression support for the format
		     version 0 was removed in lzip 1.18.

		     lzip 1.4 and later create files in the format version  1.
		     The  sync	flush marker extension to the format version 1
		     was added in lzip 1.6.  This extension is rarely used and
		     isn't supported by xz (diagnosed as corrupt input).

	      raw    Compress  or  uncompress a raw stream (no headers).  This
		     is meant for advanced users only.	To decode raw streams,
		     you need use --format=raw and explicitly specify the fil‐
		     ter chain, which normally would have been stored  in  the
		     container headers.

       -C check, --check=check
	      Specify  the  type  of the integrity check.  The check is calcu‐
	      lated from the uncompressed data and stored  in  the  .xz	 file.
	      This  option  has	 an  effect only when compressing into the .xz
	      format; the .lzma format doesn't support integrity checks.   The
	      integrity check (if any) is verified when the .xz file is decom‐
	      pressed.

	      Supported check types:

	      none   Don't calculate an integrity check at all.	 This is  usu‐
		     ally  a  bad  idea.  This can be useful when integrity of
		     the data is verified by other means anyway.

	      crc32  Calculate CRC32  using  the  polynomial  from  IEEE-802.3
		     (Ethernet).

	      crc64  Calculate CRC64 using the polynomial from ECMA-182.  This
		     is the default, since it is slightly better than CRC32 at
		     detecting	damaged files and the speed difference is neg‐
		     ligible.

	      sha256 Calculate SHA-256.	 This is somewhat  slower  than	 CRC32
		     and CRC64.

	      Integrity	 of the .xz headers is always verified with CRC32.  It
	      is not possible to change or disable it.

       --ignore-check
	      Don't verify the integrity check of the compressed data when de‐
	      compressing.   The CRC32 values in the .xz headers will still be
	      verified normally.

	      Do not use this option unless you know what you are doing.  Pos‐
	      sible reasons to use this option:

	      •	 Trying to recover data from a corrupt .xz file.

	      •	 Speeding  up decompression.  This matters mostly with SHA-256
		 or with files that have compressed extremely well.  It's rec‐
		 ommended  to  not use this option for this purpose unless the
		 file integrity is verified externally in some other way.

       -0 ... -9
	      Select a compression preset level.  The default is -6.  If  mul‐
	      tiple  preset  levels  are specified, the last one takes effect.
	      If a custom filter chain was already specified, setting  a  com‐
	      pression preset level clears the custom filter chain.

	      The  differences	between	 the presets are more significant than
	      with gzip(1) and bzip2(1).  The  selected	 compression  settings
	      determine	 the memory requirements of the decompressor, thus us‐
	      ing a too high preset level might make it painful to  decompress
	      the  file	 on an old system with little RAM.  Specifically, it's
	      not a good idea to blindly use -9 for everything like  it	 often
	      is with gzip(1) and bzip2(1).

	      -0 ... -3
		     These  are somewhat fast presets.	-0 is sometimes faster
		     than gzip -9 while compressing much better.   The	higher
		     ones  often have speed comparable to bzip2(1) with compa‐
		     rable or better compression ratio, although  the  results
		     depend a lot on the type of data being compressed.

	      -4 ... -6
		     Good  to very good compression while keeping decompressor
		     memory usage reasonable even for old systems.  -6 is  the
		     default,  which is usually a good choice for distributing
		     files that need to be decompressible even on systems with
		     only  16 MiB  RAM.	  (-5e or -6e may be worth considering
		     too.  See --extreme.)

	      -7 ... -9
		     These are like -6 but with higher compressor  and	decom‐
		     pressor  memory requirements.  These are useful only when
		     compressing files bigger than 8 MiB, 16 MiB, and  32 MiB,
		     respectively.

	      On the same hardware, the decompression speed is approximately a
	      constant number of bytes of  compressed  data  per  second.   In
	      other  words,  the better the compression, the faster the decom‐
	      pression will usually be.	 This also means that  the  amount  of
	      uncompressed output produced per second can vary a lot.

	      The following table summarises the features of the presets:

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem -0;256 KiB;0;3 MiB;1 MiB -1;1 MiB;1;9
		     MiB;2 MiB -2;2 MiB;2;17 MiB;3 MiB -3;4 MiB;3;32 MiB;5 MiB
		     -4;4 MiB;4;48 MiB;5 MiB  -5;8  MiB;5;94  MiB;9  MiB  -6;8
		     MiB;6;94  MiB;9  MiB  -7;16  MiB;6;186  MiB;17  MiB -8;32
		     MiB;6;370 MiB;33 MiB -9;64 MiB;6;674 MiB;65 MiB

	      Column descriptions:

	      •	 DictSize is the LZMA2 dictionary size.	 It is waste of memory
		 to  use a dictionary bigger than the size of the uncompressed
		 file.	This is why it is good to avoid using the  presets  -7
		 ...  -9 when there's no real need for them.  At -6 and lower,
		 the amount of memory wasted is usually low enough to not mat‐
		 ter.

	      •	 CompCPU  is a simplified representation of the LZMA2 settings
		 that affect compression speed.	 The dictionary	 size  affects
		 speed too, so while CompCPU is the same for levels -6 ... -9,
		 higher levels still tend to be a little slower.  To get  even
		 slower and thus possibly better compression, see --extreme.

	      •	 CompMem  contains  the	 compressor memory requirements in the
		 single-threaded mode.	It may vary slightly between  xz  ver‐
		 sions.

	      •	 DecMem	 contains  the decompressor memory requirements.  That
		 is, the compression settings determine	 the  memory  require‐
		 ments of the decompressor.  The exact decompressor memory us‐
		 age is slightly more than the LZMA2 dictionary size, but  the
		 values	 in  the  table	 have been rounded up to the next full
		 MiB.

	      Memory requirements of the multi-threaded mode are significantly
	      higher  than that of the single-threaded mode.  With the default
	      value of --block-size, each thread needs 3*3*DictSize plus Comp‐
	      Mem  or  DecMem.	For example, four threads with preset -6 needs
	      660–670 MiB of memory.

       -e, --extreme
	      Use a slower variant of the selected  compression	 preset	 level
	      (-0 ... -9) to hopefully get a little bit better compression ra‐
	      tio, but with bad luck this can also make it worse.   Decompres‐
	      sor  memory  usage  is not affected, but compressor memory usage
	      increases a little at preset levels -0 ... -3.

	      Since there are two presets  with	 dictionary  sizes  4 MiB  and
	      8 MiB,  the  presets  -3e	 and  -5e use slightly faster settings
	      (lower CompCPU) than -4e and -6e, respectively.  That way no two
	      presets are identical.

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem  -0e;256  KiB;8;4  MiB;1  MiB	 -1e;1
		     MiB;8;13	MiB;2  MiB  -2e;2  MiB;8;25  MiB;3  MiB	 -3e;4
		     MiB;7;48  MiB;5  MiB  -4e;4  MiB;8;48  MiB;5  MiB	 -5e;8
		     MiB;7;94  MiB;9  MiB  -6e;8  MiB;8;94  MiB;9  MiB	-7e;16
		     MiB;8;186 MiB;17 MiB -8e;32 MiB;8;370 MiB;33  MiB	-9e;64
		     MiB;8;674 MiB;65 MiB

	      For  example,  there  are a total of four presets that use 8 MiB
	      dictionary, whose order from the fastest to the slowest  is  -5,
	      -6, -5e, and -6e.

       --fast
       --best These  are  somewhat  misleading	aliases for -0 and -9, respec‐
	      tively.  These are provided  only	 for  backwards	 compatibility
	      with LZMA Utils.	Avoid using these options.

       --block-size=size
	      When  compressing	 to  the .xz format, split the input data into
	      blocks of size bytes.  The blocks are  compressed	 independently
	      from each other, which helps with multi-threading and makes lim‐
	      ited random-access decompression possible.  This option is typi‐
	      cally  used to override the default block size in multi-threaded
	      mode, but this option can be used in single-threaded mode too.

	      In multi-threaded mode about three times size bytes will be  al‐
	      located  in each thread for buffering input and output.  The de‐
	      fault size is three times the LZMA2 dictionary size  or  1  MiB,
	      whichever is more.  Typically a good value is 2–4 times the size
	      of the LZMA2 dictionary or at least 1 MiB.  Using size less than
	      the LZMA2 dictionary size is waste of RAM because then the LZMA2
	      dictionary buffer will never get fully used.  In	multi-threaded
	      mode,  the  sizes of the blocks are stored in the block headers.
	      This size information is required for multi-threaded  decompres‐
	      sion.

	      In  single-threaded  mode no block splitting is done by default.
	      Setting this option doesn't affect memory usage.	No size infor‐
	      mation is stored in block headers, thus files created in single-
	      threaded mode won't be identical	to  files  created  in	multi-
	      threaded	mode.  The lack of size information also means that xz
	      won't be able decompress the files in multi-threaded mode.

       --block-list=items
	      When compressing to the .xz format, start a new  block  with  an
	      optional custom filter chain after the given intervals of uncom‐
	      pressed data.

	      The items are a comma-separated list.  Each item consists of  an
	      optional filter chain number between 0 and 9 followed by a colon
	      (:) and a required size of uncompressed data.  Omitting an  item
	      (two  or more consecutive commas) is a shorthand to use the size
	      and filters of the previous item.

	      If the input file is bigger than the sum of the sizes in	items,
	      the  last item is repeated until the end of the file.  A special
	      value of 0 may be used as the last size  to  indicate  that  the
	      rest of the file should be encoded as a single block.

	      An  alternative  filter chain for each block can be specified in
	      combination with the --filters1=filters  ...  --filters9=filters
	      options.	 These options define filter chains with an identifier
	      between 1–9.  Filter chain 0 can be used to refer to the default
	      filter  chain,  which  is	 the  same  as not specifying a filter
	      chain.  The filter chain identifier can be used before  the  un‐
	      compressed  size,	 followed by a colon (:).  For example, if one
	      specifies	 --block-list=1:2MiB,3:2MiB,2:4MiB,,2MiB,0:4MiB	  then
	      blocks will be created using:

	      •	 The filter chain specified by --filters1 and 2 MiB input

	      •	 The filter chain specified by --filters3 and 2 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The default filter chain and 2 MiB input

	      •	 The  default filter chain and 4 MiB input for every block un‐
		 til end of input.

	      If one specifies a size that exceeds the	encoder's  block  size
	      (either  the  default value in threaded mode or the value speci‐
	      fied with --block-size=size), the encoder will create additional
	      blocks while keeping the boundaries specified in items.  For ex‐
	      ample,	  if	  one	    specifies	    --block-size=10MiB
	      --block-list=5MiB,10MiB,8MiB,12MiB,24MiB	and  the input file is
	      80 MiB, one will get 11 blocks: 5, 10, 8, 10, 2, 10, 10, 4,  10,
	      10, and 1 MiB.

	      In multi-threaded mode the sizes of the blocks are stored in the
	      block headers.  This isn't done in single-threaded mode, so  the
	      encoded  output won't be identical to that of the multi-threaded
	      mode.

       --flush-timeout=timeout
	      When compressing, if more than timeout milliseconds (a  positive
	      integer)	has  passed  since the previous flush and reading more
	      input would block, all the pending input data  is	 flushed  from
	      the  encoder  and made available in the output stream.  This can
	      be useful if xz is used to compress data that is streamed over a
	      network.	 Small	timeout	 values make the data available at the
	      receiving end with a small delay, but large timeout values  give
	      better compression ratio.

	      This  feature  is disabled by default.  If this option is speci‐
	      fied more than once, the last one	 takes	effect.	  The  special
	      timeout  value  of 0 can be used to explicitly disable this fea‐
	      ture.

	      This feature is not available on non-POSIX systems.

	      This feature is still experimental.  Currently xz is  unsuitable
	      for  decompressing  the  stream  in real time due to how xz does
	      buffering.

       --memlimit-compress=limit
	      Set a memory usage limit for compression.	  If  this  option  is
	      specified multiple times, the last one takes effect.

	      If the compression settings exceed the limit, xz will attempt to
	      adjust the settings downwards so that the limit is no longer ex‐
	      ceeded  and display a notice that automatic adjustment was done.
	      The adjustments are done in this order: reducing the  number  of
	      threads, switching to single-threaded mode if even one thread in
	      multi-threaded mode exceeds the limit, and finally reducing  the
	      LZMA2 dictionary size.

	      When  compressing	 with  --format=raw or if --no-adjust has been
	      specified, only the number of threads may be  reduced  since  it
	      can be done without affecting the compressed output.

	      If  the  limit cannot be met even with the adjustments described
	      above, an error is displayed and xz will exit with  exit	status
	      1.

	      The limit can be specified in multiple ways:

	      •	 The  limit can be an absolute value in bytes.	Using an inte‐
		 ger suffix like MiB can be useful.  Example:  --memlimit-com‐
		 press=80MiB

	      •	 The  limit can be specified as a percentage of total physical
		 memory (RAM).	This can be useful especially when setting the
		 XZ_DEFAULTS  environment  variable  in a shell initialization
		 script that is shared between different computers.  That  way
		 the  limit  is automatically bigger on systems with more mem‐
		 ory.  Example: --memlimit-compress=70%

	      •	 The limit can be reset back to its default value  by  setting
		 it  to	 0.  This is currently equivalent to setting the limit
		 to max (no memory usage limit).

	      For 32-bit xz there is a special case: if	 the  limit  would  be
	      over 4020 MiB, the limit is set to 4020 MiB.  On MIPS32 2000 MiB
	      is used instead.	(The values 0 and max aren't affected by this.
	      A similar feature doesn't exist for decompression.)  This can be
	      helpful when a 32-bit executable has  access  to	4 GiB  address
	      space  (2	 GiB on MIPS32) while hopefully doing no harm in other
	      situations.

	      See also the section Memory usage.

       --memlimit-decompress=limit
	      Set a memory usage limit for decompression.  This	 also  affects
	      the  --list  mode.  If the operation is not possible without ex‐
	      ceeding the limit, xz will display an  error  and	 decompressing
	      the  file will fail.  See --memlimit-compress=limit for possible
	      ways to specify the limit.

       --memlimit-mt-decompress=limit
	      Set a memory usage limit for multi-threaded decompression.  This
	      can  only	 affect the number of threads; this will never make xz
	      refuse to decompress a file.  If limit is too low to  allow  any
	      multi-threading,	the  limit  is ignored and xz will continue in
	      single-threaded mode.  Note that if  also	 --memlimit-decompress
	      is used, it will always apply to both single-threaded and multi-
	      threaded modes, and so the effective limit  for  multi-threading
	      will  never  be higher than the limit set with --memlimit-decom‐
	      press.

	      In contrast to the other	memory	usage  limit  options,	--mem‐
	      limit-mt-decompress=limit	 has  a system-specific default limit.
	      xz --info-memory can be used to see the current value.

	      This option and its default  value  exist	 because  without  any
	      limit  the  threaded decompressor could end up allocating an in‐
	      sane amount of memory with some input  files.   If  the  default
	      limit is too low on your system, feel free to increase the limit
	      but never set it to a value larger than the amount of usable RAM
	      as  with	appropriate  input  files  xz will attempt to use that
	      amount of memory even with a low number of threads.  Running out
	      of  memory  or  swapping	will not improve decompression perfor‐
	      mance.

	      See --memlimit-compress=limit for possible ways to  specify  the
	      limit.   Setting limit to 0 resets the limit to the default sys‐
	      tem-specific value.

       -M limit, --memlimit=limit, --memory=limit
	      This  is	equivalent  to	specifying   --memlimit-compress=limit
	      --memlimit-decompress=limit --memlimit-mt-decompress=limit.

       --no-adjust
	      Display  an  error  and exit if the memory usage limit cannot be
	      met without adjusting settings that affect the  compressed  out‐
	      put.   That is, this prevents xz from switching the encoder from
	      multi-threaded mode to single-threaded mode  and	from  reducing
	      the  LZMA2  dictionary  size.  Even when this option is used the
	      number of threads may be reduced to meet the memory usage	 limit
	      as that won't affect the compressed output.

	      Automatic adjusting is always disabled when creating raw streams
	      (--format=raw).

       -T threads, --threads=threads
	      Specify the number of worker threads to use.  Setting threads to
	      a special value 0 makes xz use up to as many threads as the pro‐
	      cessor(s) on the system support.	The actual number  of  threads
	      can  be  fewer  than threads if the input file is not big enough
	      for threading with the given settings or if using	 more  threads
	      would exceed the memory usage limit.

	      The  single-threaded and multi-threaded compressors produce dif‐
	      ferent output.  Single-threaded compressor will give the	small‐
	      est  file	 size but only the output from the multi-threaded com‐
	      pressor can be decompressed  using  multiple  threads.   Setting
	      threads to 1 will use the single-threaded mode.  Setting threads
	      to any other value, including 0,	will  use  the	multi-threaded
	      compressor even if the system supports only one hardware thread.
	      (xz 5.2.x used single-threaded mode in this situation.)

	      To use multi-threaded mode with only one thread, set threads  to
	      +1.   The	 +  prefix  has no effect with values other than 1.  A
	      memory usage limit can still make xz switch  to  single-threaded
	      mode  unless  --no-adjust is used.  Support for the + prefix was
	      added in xz 5.4.0.

	      If an automatic number of threads has been requested and no mem‐
	      ory  usage  limit has been specified, then a system-specific de‐
	      fault soft limit will be used to possibly limit  the  number  of
	      threads.	 It is a soft limit in sense that it is ignored if the
	      number of threads becomes one, thus a soft limit will never stop
	      xz  from	compressing or decompressing.  This default soft limit
	      will not make xz switch  from  multi-threaded  mode  to  single-
	      threaded	 mode.	  The  active  limits  can  be	seen  with  xz
	      --info-memory.

	      Currently the only threading method is to split the  input  into
	      blocks and compress them independently from each other.  The de‐
	      fault block size depends on the compression  level  and  can  be
	      overridden with the --block-size=size option.

	      Threaded decompression only works on files that contain multiple
	      blocks with size information in block headers.  All large enough
	      files compressed in multi-threaded mode meet this condition, but
	      files  compressed	 in  single-threaded  mode   don't   even   if
	      --block-size=size has been used.

	      The  default  value for threads is 0.  In xz 5.4.x and older the
	      default is 1.

   Custom compressor filter chains
       A custom filter chain allows specifying the compression settings in de‐
       tail  instead  of  relying  on  the settings associated to the presets.
       When a custom filter chain is specified, preset options (-0 ... -9  and
       --extreme)  earlier on the command line are forgotten.  If a preset op‐
       tion is specified after one or more custom filter  chain	 options,  the
       new  preset  takes effect and the custom filter chain options specified
       earlier are forgotten.

       A filter chain is comparable to piping on the command line.  When  com‐
       pressing, the uncompressed input goes to the first filter, whose output
       goes to the next filter (if any).  The output of the last  filter  gets
       written	to  the compressed file.  The maximum number of filters in the
       chain is four, but typically a filter chain has only one	 or  two  fil‐
       ters.

       Many filters have limitations on where they can be in the filter chain:
       some filters can work only as the last filter in the chain,  some  only
       as  a non-last filter, and some work in any position in the chain.  De‐
       pending on the filter, this limitation is either inherent to the filter
       design or exists to prevent security issues.

       A  custom filter chain can be specified in two different ways.  The op‐
       tions --filters=filters and --filters1=filters  ...  --filters9=filters
       allow specifying an entire filter chain in one option using the liblzma
       filter string syntax.  Alternatively, a filter chain can	 be  specified
       by  using  one  or more individual filter options in the order they are
       wanted in the filter chain.  That is, the order of the individual  fil‐
       ter  options is significant!  When decoding raw streams (--format=raw),
       the filter chain must be specified in the same order as it  was	speci‐
       fied  when compressing.	Any individual filter or preset options speci‐
       fied before the full chain option (--filters=filters) will  be  forgot‐
       ten.  Individual filters specified after the full chain option will re‐
       set the filter chain.

       Both the full and individual filter options  take  filter-specific  op‐
       tions  as a comma-separated list.  Extra commas in options are ignored.
       Every option has a default value, so specify those you want to change.

       To see the whole filter chain and options, use xz  -vv  (that  is,  use
       --verbose twice).  This works also for viewing the filter chain options
       used by presets.

       --filters=filters
	      Specify the full filter chain or a preset in  a  single  option.
	      Each filter can be separated by spaces or two dashes (--).  fil‐
	      ters may need to be quoted on the shell command line  so	it  is
	      parsed  as  a  single option.  To denote options, use : or =.  A
	      preset can be prefixed with a - and followed with zero  or  more
	      flags.   The  only supported flag is e to apply the same options
	      as --extreme.

       --filters1=filters ... --filters9=filters
	      Specify up to nine additional filter chains  that	 can  be  used
	      with --block-list.

	      For  example,  when compressing an archive with executable files
	      followed by text files, the executable part could use  a	filter
	      chain with a BCJ filter and the text part only the LZMA2 filter.

       --filters-help
	      Display  a  help	message	 describing how to specify presets and
	      custom filter chains in the --filters and --filters1=filters ...
	      --filters9=filters options, and exit successfully.

       --lzma1[=options]
       --lzma2[=options]
	      Add  LZMA1  or  LZMA2 filter to the filter chain.	 These filters
	      can be used only as the last filter in the chain.

	      LZMA1 is a legacy filter, which is supported almost  solely  due
	      to  the  legacy  .lzma  file  format, which supports only LZMA1.
	      LZMA2 is an updated version of LZMA1 to fix some	practical  is‐
	      sues  of	LZMA1.	 The .xz format uses LZMA2 and doesn't support
	      LZMA1 at all.  Compression speed and ratios of LZMA1  and	 LZMA2
	      are practically the same.

	      LZMA1 and LZMA2 share the same set of options:

	      preset=preset
		     Reset  all LZMA1 or LZMA2 options to preset.  Preset con‐
		     sist of an integer, which may be followed by  single-let‐
		     ter  preset  modifiers.   The integer can be from 0 to 9,
		     matching the command line options -0 ...  -9.   The  only
		     supported	modifier  is  currently e, which matches --ex‐
		     treme.  If no preset is specified, the default values  of
		     LZMA1 or LZMA2 options are taken from the preset 6.

	      dict=size
		     Dictionary (history buffer) size indicates how many bytes
		     of the recently processed uncompressed data  is  kept  in
		     memory.   The  algorithm tries to find repeating byte se‐
		     quences (matches) in the uncompressed data,  and  replace
		     them with references to the data currently in the dictio‐
		     nary.  The bigger	the  dictionary,  the  higher  is  the
		     chance to find a match.  Thus, increasing dictionary size
		     usually improves compression ratio, but a dictionary big‐
		     ger than the uncompressed file is waste of memory.

		     Typical  dictionary  size	is from 64 KiB to 64 MiB.  The
		     minimum is 4 KiB.	The maximum for	 compression  is  cur‐
		     rently 1.5 GiB (1536 MiB).	 The decompressor already sup‐
		     ports dictionaries up to one byte less than 4 GiB,	 which
		     is the maximum for the LZMA1 and LZMA2 stream formats.

		     Dictionary	 size and match finder (mf) together determine
		     the memory usage of the LZMA1 or LZMA2 encoder.  The same
		     (or bigger) dictionary size is required for decompressing
		     that was used when compressing, thus the memory usage  of
		     the  decoder  is  determined  by the dictionary size used
		     when compressing.	The .xz headers store  the  dictionary
		     size  either  as 2^n or 2^n + 2^(n-1), so these sizes are
		     somewhat preferred for compression.  Other sizes will get
		     rounded up when stored in the .xz headers.

	      lc=lc  Specify  the number of literal context bits.  The minimum
		     is 0 and the maximum is 4; the default is	3.   In	 addi‐
		     tion, the sum of lc and lp must not exceed 4.

		     All  bytes	 that cannot be encoded as matches are encoded
		     as literals.  That is, literals are  simply  8-bit	 bytes
		     that are encoded one at a time.

		     The  literal  coding makes an assumption that the highest
		     lc bits of the previous uncompressed byte correlate  with
		     the  next byte.  For example, in typical English text, an
		     upper-case letter is often followed by a lower-case  let‐
		     ter,  and	a lower-case letter is usually followed by an‐
		     other lower-case letter.  In the US-ASCII character  set,
		     the highest three bits are 010 for upper-case letters and
		     011 for lower-case letters.  When lc is at least  3,  the
		     literal coding can take advantage of this property in the
		     uncompressed data.

		     The default value (3) is usually good.  If you want maxi‐
		     mum compression, test lc=4.  Sometimes it helps a little,
		     and sometimes it makes compression worse.	If it makes it
		     worse, test lc=2 too.

	      lp=lp  Specify the number of literal position bits.  The minimum
		     is 0 and the maximum is 4; the default is 0.

		     Lp affects what kind of  alignment	 in  the  uncompressed
		     data is assumed when encoding literals.  See pb below for
		     more information about alignment.

	      pb=pb  Specify the number of position bits.  The	minimum	 is  0
		     and the maximum is 4; the default is 2.

		     Pb	 affects  what	kind  of alignment in the uncompressed
		     data is assumed in general.  The default means  four-byte
		     alignment (2^pb=2^2=4), which is often a good choice when
		     there's no better guess.

		     When the alignment is known, setting pb  accordingly  may
		     reduce  the  file	size a little.	For example, with text
		     files having one-byte  alignment  (US-ASCII,  ISO-8859-*,
		     UTF-8),  setting  pb=0  can improve compression slightly.
		     For UTF-16 text, pb=1 is a good choice.  If the alignment
		     is	 an  odd  number  like 3 bytes, pb=0 might be the best
		     choice.

		     Even though the assumed alignment can be adjusted with pb
		     and  lp,  LZMA1  and  LZMA2  still slightly favor 16-byte
		     alignment.	 It might be worth taking  into	 account  when
		     designing	file  formats that are likely to be often com‐
		     pressed with LZMA1 or LZMA2.

	      mf=mf  Match finder has a major effect on encoder speed,	memory
		     usage,  and  compression ratio.  Usually Hash Chain match
		     finders are faster than Binary Tree match	finders.   The
		     default  depends  on the preset: 0 uses hc3, 1–3 use hc4,
		     and the rest use bt4.

		     The following match finders are  supported.   The	memory
		     usage  formulas below are rough approximations, which are
		     closest to the reality when dict is a power of two.

		     hc3    Hash Chain with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 7.5 (if dict <= 16 MiB);
			    dict * 5.5 + 64 MiB (if dict > 16 MiB)

		     hc4    Hash Chain with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 7.5 (if dict <= 32 MiB);
			    dict * 6.5 (if dict > 32 MiB)

		     bt2    Binary Tree with 2-byte hashing
			    Minimum value for nice: 2
			    Memory usage: dict * 9.5

		     bt3    Binary Tree with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 11.5 (if dict <= 16 MiB);
			    dict * 9.5 + 64 MiB (if dict > 16 MiB)

		     bt4    Binary Tree with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 11.5 (if dict <= 32 MiB);
			    dict * 10.5 (if dict > 32 MiB)

	      mode=mode
		     Compression mode specifies the method to analyze the data
		     produced  by  the match finder.  Supported modes are fast
		     and normal.  The default is fast for presets 0–3 and nor‐
		     mal for presets 4–9.

		     Usually  fast  is	used with Hash Chain match finders and
		     normal with Binary Tree match finders.  This is also what
		     the presets do.

	      nice=nice
		     Specify  what  is	considered  to	be a nice length for a
		     match.  Once a match of at least nice bytes is found, the
		     algorithm stops looking for possibly better matches.

		     Nice can be 2–273 bytes.  Higher values tend to give bet‐
		     ter compression ratio at the expense of speed.   The  de‐
		     fault depends on the preset.

	      depth=depth
		     Specify  the  maximum  search  depth in the match finder.
		     The default is the special value of 0,  which  makes  the
		     compressor determine a reasonable depth from mf and nice.

		     Reasonable depth for Hash Chains is 4–100 and 16–1000 for
		     Binary Trees.  Using very high values for depth can  make
		     the  encoder  extremely slow with some files.  Avoid set‐
		     ting the depth over 1000 unless you are prepared  to  in‐
		     terrupt  the  compression	in  case  it is taking far too
		     long.

	      When decoding raw streams (--format=raw), LZMA2 needs  only  the
	      dictionary size.	LZMA1 needs also lc, lp, and pb.

       --x86[=options]
       --arm[=options]
       --armthumb[=options]
       --arm64[=options]
       --powerpc[=options]
       --ia64[=options]
       --sparc[=options]
       --riscv[=options]
	      Add  a branch/call/jump (BCJ) filter to the filter chain.	 These
	      filters can be used only as a  non-last  filter  in  the	filter
	      chain.

	      A	 BCJ filter converts relative addresses in the machine code to
	      their absolute counterparts.  This doesn't change	 the  size  of
	      the  data	 but  it increases redundancy, which can help LZMA2 to
	      produce 0–15 % smaller .xz file.	The BCJ filters are always re‐
	      versible,	 so  using a BCJ filter for wrong type of data doesn't
	      cause any data loss, although it may make the compression	 ratio
	      slightly	worse.	 The  BCJ filters are very fast and use an in‐
	      significant amount of memory.

	      These BCJ filters have known problems related to the compression
	      ratio:

	      •	 Some  types of files containing executable code (for example,
		 object files, static libraries,  and  Linux  kernel  modules)
		 have  the  addresses  in  the instructions filled with filler
		 values.  These BCJ filters will still do the address  conver‐
		 sion, which will make the compression worse with these files.

	      •	 If a BCJ filter is applied on an archive, it is possible that
		 it makes the compression ratio worse than  not	 using	a  BCJ
		 filter.   For example, if there are similar or even identical
		 executables then filtering will likely make  the  files  less
		 similar  and thus compression is worse.  The contents of non-
		 executable files in the same  archive	can  matter  too.   In
		 practice  one has to try with and without a BCJ filter to see
		 which is better in each situation.

	      Different instruction sets have different	 alignment:  the  exe‐
	      cutable  file must be aligned to a multiple of this value in the
	      input data to make the filter work.

		     tab(;); l n l l n l.  Filter;Alignment;Notes x86;1;32-bit
		     or	  64-bit  x86  ARM;4;  ARM-Thumb;2;  ARM64;4;4096-byte
		     alignment is best PowerPC;4;Big endian only IA-64;16;Ita‐
		     nium SPARC;4; RISC-V;2;

	      Since  the  BCJ-filtered	data is usually compressed with LZMA2,
	      the compression ratio may be improved slightly if the LZMA2  op‐
	      tions are set to match the alignment of the selected BCJ filter.
	      Examples:

	      •	 IA-64 filter has 16-byte alignment so pb=4,lp=4,lc=0 is  good
		 with LZMA2 (2^4=16).

	      •	 RISC-V	 code  has  2-byte  or	4-byte	alignment depending on
		 whether the file contains 16-bit compressed instructions (the
		 C   extension).    When   16-bit   instructions   are	 used,
		 pb=2,lp=1,lc=3 or pb=1,lp=1,lc=3 is good.   When  16-bit  in‐
		 structions aren't present, pb=2,lp=2,lc=2 is the best.	 read‐
		 elf -h can be used to check if "RVC" appears on  the  "Flags"
		 line.

	      •	 ARM64 is always 4-byte aligned so pb=2,lp=2,lc=2 is the best.

	      •	 The  x86  filter is an exception.  It's usually good to stick
		 to LZMA2's defaults (pb=2,lp=0,lc=3) when compressing x86 ex‐
		 ecutables.

	      All BCJ filters support the same options:

	      start=offset
		     Specify the start offset that is used when converting be‐
		     tween relative and absolute addresses.  The  offset  must
		     be a multiple of the alignment of the filter (see the ta‐
		     ble above).  The default is zero.	In practice,  the  de‐
		     fault is good; specifying a custom offset is almost never
		     useful.

       --delta[=options]
	      Add the Delta filter to the filter chain.	 The Delta filter  can
	      be only used as a non-last filter in the filter chain.

	      Currently	 only simple byte-wise delta calculation is supported.
	      It can be useful when  compressing,  for	example,  uncompressed
	      bitmap  images or uncompressed PCM audio.	 However, special pur‐
	      pose algorithms may give significantly better results than Delta
	      +	 LZMA2.	  This is true especially with audio, which compresses
	      faster and better, for example, with flac(1).

	      Supported options:

	      dist=distance
		     Specify the distance of the delta calculation  in	bytes.
		     distance must be 1–256.  The default is 1.

		     For example, with dist=2 and eight-byte input A1 B1 A2 B3
		     A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

   Other options
       -q, --quiet
	      Suppress warnings and notices.  Specify this twice  to  suppress
	      errors too.  This option has no effect on the exit status.  That
	      is, even if a warning was suppressed, the exit status  to	 indi‐
	      cate a warning is still used.

       -v, --verbose
	      Be  verbose.   If	 standard error is connected to a terminal, xz
	      will display a progress indicator.  Specifying  --verbose	 twice
	      will give even more verbose output.

	      The progress indicator shows the following information:

	      •	 Completion  percentage is shown if the size of the input file
		 is known.  That is, the percentage cannot be shown in pipes.

	      •	 Amount of compressed data produced (compressing) or  consumed
		 (decompressing).

	      •	 Amount	 of  uncompressed  data consumed (compressing) or pro‐
		 duced (decompressing).

	      •	 Compression ratio, which is calculated by dividing the amount
		 of  compressed	 data processed so far by the amount of uncom‐
		 pressed data processed so far.

	      •	 Compression or decompression speed.  This is measured as  the
		 amount	 of  uncompressed  data consumed (compression) or pro‐
		 duced (decompression) per second.  It is shown	 after	a  few
		 seconds have passed since xz started processing the file.

	      •	 Elapsed time in the format M:SS or H:MM:SS.

	      •	 Estimated  remaining  time is shown only when the size of the
		 input file is known and a  couple  of	seconds	 have  already
		 passed	 since	xz  started  processing the file.  The time is
		 shown in a less precise format which never  has  any  colons,
		 for example, 2 min 30 s.

	      When  standard  error  is not a terminal, --verbose will make xz
	      print the filename, compressed size, uncompressed size, compres‐
	      sion  ratio,  and	 possibly also the speed and elapsed time on a
	      single line to standard error after compressing or decompressing
	      the file.	 The speed and elapsed time are included only when the
	      operation took at least a few seconds.  If the operation	didn't
	      finish,  for example, due to user interruption, also the comple‐
	      tion percentage is printed if the size  of  the  input  file  is
	      known.

       -Q, --no-warn
	      Don't set the exit status to 2 even if a condition worth a warn‐
	      ing was detected.	 This  option  doesn't	affect	the  verbosity
	      level,  thus  both  --quiet and --no-warn have to be used to not
	      display warnings and to not alter the exit status.

       --robot
	      Print messages in a machine-parsable format.  This  is  intended
	      to  ease	writing	 frontends  that want to use xz instead of li‐
	      blzma, which may be the case with various scripts.   The	output
	      with  this  option  enabled  is meant to be stable across xz re‐
	      leases.  See the section ROBOT MODE for details.

       --info-memory
	      Display, in human-readable  format,  how	much  physical	memory
	      (RAM)  and  how  many processor threads xz thinks the system has
	      and the memory usage limits for compression  and	decompression,
	      and exit successfully.

       -h, --help
	      Display  a  help	message	 describing the most commonly used op‐
	      tions, and exit successfully.

       -H, --long-help
	      Display a help message describing all features of xz,  and  exit
	      successfully

       -V, --version
	      Display  the  version number of xz and liblzma in human readable
	      format.  To get machine-parsable output, specify --robot	before
	      --version.

ROBOT MODE
       The robot mode is activated with the --robot option.  It makes the out‐
       put of xz easier to parse by other programs.  Currently --robot is sup‐
       ported  only  together  with --list, --filters-help, --info-memory, and
       --version.  It will be supported for compression and  decompression  in
       the future.

   List mode
       xz --robot --list uses tab-separated output.  The first column of every
       line has a string that indicates the type of the information  found  on
       that line:

       name   This is always the first line when starting to list a file.  The
	      second column on the line is the filename.

       file   This line contains overall information about the .xz file.  This
	      line is always printed after the name line.

       stream This line type is used only when --verbose was specified.	 There
	      are as many stream lines as there are streams in the .xz file.

       block  This line type is used only when --verbose was specified.	 There
	      are  as  many  block  lines as there are blocks in the .xz file.
	      The block lines are shown after all the stream lines;  different
	      line types are not interleaved.

       summary
	      This  line type is used only when --verbose was specified twice.
	      This line is printed after all block lines.  Like the file line,
	      the  summary  line  contains  overall  information about the .xz
	      file.

       totals This line is always the very last line of the list  output.   It
	      shows the total counts and sizes.

       The columns of the file lines:
	      2.  Number of streams in the file
	      3.  Total number of blocks in the stream(s)
	      4.  Compressed size of the file
	      5.  Uncompressed size of the file
	      6.  Compression  ratio,  for  example,  0.123.  If ratio is over
		  9.999, three dashes (---) are displayed instead of  the  ra‐
		  tio.
	      7.  Comma-separated  list of integrity check names.  The follow‐
		  ing strings are used for the known check types: None, CRC32,
		  CRC64,  and  SHA-256.	 For unknown check types, Unknown-N is
		  used, where N is the Check ID as a decimal  number  (one  or
		  two digits).
	      8.  Total size of stream padding in the file

       The columns of the stream lines:
	      2.  Stream number (the first stream is 1)
	      3.  Number of blocks in the stream
	      4.  Compressed start offset
	      5.  Uncompressed start offset
	      6.  Compressed size (does not include stream padding)
	      7.  Uncompressed size
	      8.  Compression ratio
	      9.  Name of the integrity check
	      10. Size of stream padding

       The columns of the block lines:
	      2.  Number of the stream containing this block
	      3.  Block	 number	 relative  to the beginning of the stream (the
		  first block is 1)
	      4.  Block number relative to the beginning of the file
	      5.  Compressed start offset relative to  the  beginning  of  the
		  file
	      6.  Uncompressed	start  offset relative to the beginning of the
		  file
	      7.  Total compressed size of the block (includes headers)
	      8.  Uncompressed size
	      9.  Compression ratio
	      10. Name of the integrity check

       If --verbose was specified twice, additional columns  are  included  on
       the  block lines.  These are not displayed with a single --verbose, be‐
       cause getting this information requires many  seeks  and	 can  thus  be
       slow:
	      11. Value of the integrity check in hexadecimal
	      12. Block header size
	      13. Block	 flags:	 c  indicates that compressed size is present,
		  and u indicates that uncompressed size is present.   If  the
		  flag	is  not	 set,  a dash (-) is shown instead to keep the
		  string length fixed.	New flags may be added to the  end  of
		  the string in the future.
	      14. Size	of  the	 actual compressed data in the block (this ex‐
		  cludes the block header, block padding, and check fields)
	      15. Amount of memory (in	bytes)	required  to  decompress  this
		  block with this xz version
	      16. Filter  chain.   Note	 that most of the options used at com‐
		  pression time cannot be known, because only the options that
		  are needed for decompression are stored in the .xz headers.

       The columns of the summary lines:
	      2.  Amount of memory (in bytes) required to decompress this file
		  with this xz version
	      3.  yes or no indicating if all block  headers  have  both  com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      4.  Minimum xz version required to decompress the file

       The columns of the totals line:
	      2.  Number of streams
	      3.  Number of blocks
	      4.  Compressed size
	      5.  Uncompressed size
	      6.  Average compression ratio
	      7.  Comma-separated  list	 of  integrity	check  names that were
		  present in the files
	      8.  Stream padding size
	      9.  Number of files.  This is here to keep the order of the ear‐
		  lier columns the same as on file lines.

       If  --verbose  was  specified twice, additional columns are included on
       the totals line:
	      10. Maximum amount of memory (in bytes) required	to  decompress
		  the files with this xz version
	      11. yes  or  no  indicating  if all block headers have both com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      12. Minimum xz version required to decompress the file

       Future versions may add new line types and new columns can be added  to
       the existing line types, but the existing columns won't be changed.

   Filters help
       xz --robot --filters-help prints the supported filters in the following
       format:

       filter:option=<value>,option=<value>...

       filter Name of the filter

       option Name of a filter specific option

       value  Numeric value ranges appear as <min-max>.	 String value  choices
	      are shown within < > and separated by a | character.

       Each filter is printed on its own line.

   Memory limit information
       xz  --robot  --info-memory prints a single line with multiple tab-sepa‐
       rated columns:

       1.  Total amount of physical memory (RAM) in bytes.

       2.  Memory usage limit for compression in bytes	(--memlimit-compress).
	   A  special  value of 0 indicates the default setting which for sin‐
	   gle-threaded mode is the same as no limit.

       3.  Memory usage limit for decompression	 in  bytes  (--memlimit-decom‐
	   press).   A	special value of 0 indicates the default setting which
	   for single-threaded mode is the same as no limit.

       4.  Since xz 5.3.4alpha: Memory usage for multi-threaded	 decompression
	   in  bytes (--memlimit-mt-decompress).  This is never zero because a
	   system-specific default value shown in the column 5 is used	if  no
	   limit  has  been  specified explicitly.  This is also never greater
	   than the value in the column 3 even if  a  larger  value  has  been
	   specified with --memlimit-mt-decompress.

       5.  Since  xz  5.3.4alpha: A system-specific default memory usage limit
	   that is used to limit the number of threads when  compressing  with
	   an  automatic  number  of threads (--threads=0) and no memory usage
	   limit has been specified (--memlimit-compress).  This is also  used
	   as the default value for --memlimit-mt-decompress.

       6.  Since xz 5.3.4alpha: Number of available processor threads.

       In  the	future,	 the  output of xz --robot --info-memory may have more
       columns, but never more than a single line.

   Version
       xz --robot --version prints the version number of xz and liblzma in the
       following format:

       XZ_VERSION=XYYYZZZS
       LIBLZMA_VERSION=XYYYZZZS

       X      Major version.

       YYY    Minor  version.  Even numbers are stable.	 Odd numbers are alpha
	      or beta versions.

       ZZZ    Patch level for stable releases or just a counter	 for  develop‐
	      ment releases.

       S      Stability.  0 is alpha, 1 is beta, and 2 is stable.  S should be
	      always 2 when YYY is even.

       XYYYZZZS are the same on both lines if xz and liblzma are from the same
       XZ Utils release.

       Examples: 4.999.9beta is 49990091 and 5.0.0 is 50000002.

EXIT STATUS
       0      All is good.

       1      An error occurred.

       2      Something	 worth	a  warning  occurred, but no actual errors oc‐
	      curred.

       Notices (not warnings or errors) printed on standard error don't affect
       the exit status.

ENVIRONMENT
       xz  parses  space-separated lists of options from the environment vari‐
       ables XZ_DEFAULTS and XZ_OPT, in this order, before parsing the options
       from  the command line.	Note that only options are parsed from the en‐
       vironment variables; all non-options are silently ignored.  Parsing  is
       done  with getopt_long(3) which is used also for the command line argu‐
       ments.

       XZ_DEFAULTS
	      User-specific or system-wide default options.  Typically this is
	      set in a shell initialization script to enable xz's memory usage
	      limiter by default.  Excluding shell initialization scripts  and
	      similar  special	cases,	scripts must never set or unset XZ_DE‐
	      FAULTS.

       XZ_OPT This is for passing options to xz when it is not possible to set
	      the  options  directly on the xz command line.  This is the case
	      when xz is run by a script or tool, for example, GNU tar(1):

		     XZ_OPT=-2v tar caf foo.tar.xz foo

	      Scripts may use XZ_OPT, for example, to set script-specific  de‐
	      fault  compression  options.   It	 is still recommended to allow
	      users to override XZ_OPT if that is reasonable.  For example, in
	      sh(1) scripts one may use something like this:

		     XZ_OPT=${XZ_OPT-"-7e"}
		     export XZ_OPT

LZMA UTILS COMPATIBILITY
       The  command  line  syntax of xz is practically a superset of lzma, un‐
       lzma, and lzcat as found from LZMA Utils 4.32.x.	 In most cases, it  is
       possible	 to replace LZMA Utils with XZ Utils without breaking existing
       scripts.	 There are some incompatibilities though, which may  sometimes
       cause problems.

   Compression preset levels
       The  numbering  of the compression level presets is not identical in xz
       and LZMA Utils.	The most important difference is how dictionary	 sizes
       are  mapped  to different presets.  Dictionary size is roughly equal to
       the decompressor memory usage.

	      tab(;); c c c c n n.  Level;xz;LZMA Utils	 -0;256	 KiB;N/A  -1;1
	      MiB;64  KiB  -2;2 MiB;1 MiB -3;4 MiB;512 KiB -4;4 MiB;1 MiB -5;8
	      MiB;2 MiB -6;8 MiB;4 MiB -7;16 MiB;8 MiB -8;32 MiB;16 MiB	 -9;64
	      MiB;32 MiB

       The dictionary size differences affect the compressor memory usage too,
       but there are some other differences between LZMA Utils and  XZ	Utils,
       which make the difference even bigger:

	      tab(;);  c  c  c c n n.  Level;xz;LZMA Utils 4.32.x -0;3 MiB;N/A
	      -1;9 MiB;2 MiB -2;17 MiB;12 MiB -3;32 MiB;12  MiB	 -4;48	MiB;16
	      MiB  -5;94  MiB;26 MiB -6;94 MiB;45 MiB -7;186 MiB;83 MiB -8;370
	      MiB;159 MiB -9;674 MiB;311 MiB

       The default preset level in LZMA Utils is -7 while in XZ	 Utils	it  is
       -6, so both use an 8 MiB dictionary by default.

   Streamed vs. non-streamed .lzma files
       The  uncompressed  size	of the file can be stored in the .lzma header.
       LZMA Utils does that when compressing regular files.   The  alternative
       is  to  mark  that  uncompressed size is unknown and use end-of-payload
       marker to indicate where the decompressor should stop.  LZMA Utils uses
       this  method when uncompressed size isn't known, which is the case, for
       example, in pipes.

       xz supports decompressing .lzma files with  or  without	end-of-payload
       marker,	but  all  .lzma	 files	created	 by xz will use end-of-payload
       marker and have uncompressed  size  marked  as  unknown	in  the	 .lzma
       header.	 This may be a problem in some uncommon situations.  For exam‐
       ple, a .lzma decompressor in an embedded device might  work  only  with
       files  that have known uncompressed size.  If you hit this problem, you
       need to use LZMA Utils or LZMA SDK to create .lzma files with known un‐
       compressed size.

   Unsupported .lzma files
       The .lzma format allows lc values up to 8, and lp values up to 4.  LZMA
       Utils can decompress files with any lc and lp, but always creates files
       with  lc=3  and	lp=0.  Creating files with other lc and lp is possible
       with xz and with LZMA SDK.

       The implementation of the LZMA1 filter in liblzma requires that the sum
       of  lc  and lp must not exceed 4.  Thus, .lzma files, which exceed this
       limitation, cannot be decompressed with xz.

       LZMA Utils creates only .lzma files which have a dictionary size of 2^n
       (a power of 2) but accepts files with any dictionary size.  liblzma ac‐
       cepts only .lzma files which have a dictionary size of  2^n  or	2^n  +
       2^(n-1).	  This	is  to	decrease  false positives when detecting .lzma
       files.

       These limitations shouldn't be a problem in practice, since practically
       all  .lzma  files  have been compressed with settings that liblzma will
       accept.

   Trailing garbage
       When decompressing, LZMA Utils silently	ignore	everything  after  the
       first  .lzma  stream.   In  most	 situations, this is a bug.  This also
       means that LZMA Utils don't support  decompressing  concatenated	 .lzma
       files.

       If  there  is  data left after the first .lzma stream, xz considers the
       file to be corrupt unless --single-stream was used.  This may break ob‐
       scure scripts which have assumed that trailing garbage is ignored.

NOTES
   Compressed output may vary
       The  exact  compressed output produced from the same uncompressed input
       file may vary between XZ Utils versions even if compression options are
       identical.  This is because the encoder can be improved (faster or bet‐
       ter compression) without affecting the file  format.   The  output  can
       vary  even  between  different  builds of the same XZ Utils version, if
       different build options are used.

       The above means that once --rsyncable has been implemented, the result‐
       ing  files won't necessarily be rsyncable unless both old and new files
       have been compressed with the same xz version.	This  problem  can  be
       fixed if a part of the encoder implementation is frozen to keep rsynca‐
       ble output stable across xz versions.

   Embedded .xz decompressors
       Embedded .xz decompressor implementations like XZ Embedded don't neces‐
       sarily support files created with integrity check types other than none
       and  crc32.   Since  the	 default  is  --check=crc64,  you   must   use
       --check=none or --check=crc32 when creating files for embedded systems.

       Outside	embedded systems, all .xz format decompressors support all the
       check types, or at least are able to decompress the file without	 veri‐
       fying the integrity check if the particular check is not supported.

       XZ  Embedded supports BCJ filters, but only with the default start off‐
       set.

EXAMPLES
   Basics
       Compress the file foo into foo.xz using the default  compression	 level
       (-6), and remove foo if compression is successful:

	      xz foo

       Decompress  bar.xz  into bar and don't remove bar.xz even if decompres‐
       sion is successful:

	      xz -dk bar.xz

       Create baz.tar.xz with the preset -4e (-4 --extreme), which  is	slower
       than  the  default -6, but needs less memory for compression and decom‐
       pression (48 MiB and 5 MiB, respectively):

	      tar cf - baz | xz -4e > baz.tar.xz

       A mix of compressed and uncompressed files can be decompressed to stan‐
       dard output with a single command:

	      xz -dcf a.txt b.txt.xz c.txt d.txt.lzma > abcd.txt

   Parallel compression of many files
       On  GNU	and *BSD, find(1) and xargs(1) can be used to parallelize com‐
       pression of many files:

	      find . -type f \! -name '*.xz' -print0 \
		  | xargs -0r -P4 -n16 xz -T1

       The -P option to xargs(1) sets the number  of  parallel	xz  processes.
       The best value for the -n option depends on how many files there are to
       be compressed.  If there are only a couple of files, the	 value	should
       probably be 1; with tens of thousands of files, 100 or even more may be
       appropriate to reduce the number of xz  processes  that	xargs(1)  will
       eventually create.

       The option -T1 for xz is there to force it to single-threaded mode, be‐
       cause xargs(1) is used to control the amount of parallelization.

   Robot mode
       Calculate how many bytes have been saved	 in  total  after  compressing
       multiple files:

	      xz --robot --list *.xz | awk '/^totals/{print $5-$4}'

       A  script may want to know that it is using new enough xz.  The follow‐
       ing sh(1) script checks that the version number of the xz  tool	is  at
       least  5.0.0.   This method is compatible with old beta versions, which
       didn't support the --robot option:

	      if ! eval "$(xz --robot --version 2> /dev/null)" ||
		      [ "$XZ_VERSION" -lt 50000002 ]; then
		  echo "Your xz is too old."
	      fi
	      unset XZ_VERSION LIBLZMA_VERSION

       Set a memory usage limit for decompression using XZ_OPT, but if a limit
       has already been set, don't increase it:

	      NEWLIM=$((123 << 20))  # 123 MiB
	      OLDLIM=$(xz --robot --info-memory | cut -f3)
	      if [ $OLDLIM -eq 0 -o $OLDLIM -gt $NEWLIM ]; then
		  XZ_OPT="$XZ_OPT --memlimit-decompress=$NEWLIM"
		  export XZ_OPT
	      fi

   Custom compressor filter chains
       The  simplest  use for custom filter chains is customizing a LZMA2 pre‐
       set.  This can be useful, because the presets cover only	 a  subset  of
       the potentially useful combinations of compression settings.

       The  CompCPU columns of the tables from the descriptions of the options
       -0 ... -9 and --extreme are  useful  when  customizing  LZMA2  presets.
       Here are the relevant parts collected from those two tables:

	      tab(;);  c  c n n.  Preset;CompCPU -0;0 -1;1 -2;2 -3;3 -4;4 -5;5
	      -6;6 -5e;7 -6e;8

       If you know that a file requires somewhat big dictionary (for  example,
       32 MiB)	to  compress well, but you want to compress it quicker than xz
       -8 would do, a preset with a low CompCPU value (for example, 1) can  be
       modified to use a bigger dictionary:

	      xz --lzma2=preset=1,dict=32MiB foo.tar

       With  certain  files,  the above command may be faster than xz -6 while
       compressing significantly better.  However, it must be emphasized  that
       only some files benefit from a big dictionary while keeping the CompCPU
       value low.  The most obvious situation, where a big dictionary can help
       a  lot,	is  an archive containing very similar files of at least a few
       megabytes each.	The dictionary size has	 to  be	 significantly	bigger
       than  any  individual file to allow LZMA2 to take full advantage of the
       similarities between consecutive files.

       If very high compressor and decompressor memory usage is fine, and  the
       file  being compressed is at least several hundred megabytes, it may be
       useful to use an even bigger dictionary than the	 64  MiB  that	xz  -9
       would use:

	      xz -vv --lzma2=dict=192MiB big_foo.tar

       Using -vv (--verbose --verbose) like in the above example can be useful
       to see the memory requirements of the compressor and decompressor.  Re‐
       member that using a dictionary bigger than the size of the uncompressed
       file is waste of memory, so the above command isn't  useful  for	 small
       files.

       Sometimes  the  compression  time  doesn't matter, but the decompressor
       memory usage has to be kept low, for example, to make  it  possible  to
       decompress  the file on an embedded system.  The following command uses
       -6e (-6 --extreme) as a base and sets the dictionary  to	 only  64 KiB.
       The  resulting  file  can  be decompressed with XZ Embedded (that's why
       there is --check=crc32) using about 100 KiB of memory.

	      xz --check=crc32 --lzma2=preset=6e,dict=64KiB foo

       If you want to squeeze out as many bytes	 as  possible,	adjusting  the
       number  of  literal  context bits (lc) and number of position bits (pb)
       can sometimes help.  Adjusting the number of literal position bits (lp)
       might help too, but usually lc and pb are more important.  For example,
       a source code archive contains mostly US-ASCII text, so something  like
       the following might give slightly (like 0.1 %) smaller file than xz -6e
       (try also without lc=4):

	      xz --lzma2=preset=6e,pb=0,lc=4 source_code.tar

       Using another filter together with LZMA2 can improve  compression  with
       certain file types.  For example, to compress a x86-32 or x86-64 shared
       library using the x86 BCJ filter:

	      xz --x86 --lzma2 libfoo.so

       Note that the order of the filter options is significant.  If --x86  is
       specified after --lzma2, xz will give an error, because there cannot be
       any filter after LZMA2, and also because the x86 BCJ filter  cannot  be
       used as the last filter in the chain.

       The  Delta filter together with LZMA2 can give good results with bitmap
       images.	It should usually beat PNG, which has a few more advanced fil‐
       ters than simple delta but uses Deflate for the actual compression.

       The  image  has to be saved in uncompressed format, for example, as un‐
       compressed TIFF.	 The distance parameter of the Delta filter is set  to
       match  the number of bytes per pixel in the image.  For example, 24-bit
       RGB bitmap needs dist=3, and it is also good to pass pb=0 to  LZMA2  to
       accommodate the three-byte alignment:

	      xz --delta=dist=3 --lzma2=pb=0 foo.tiff

       If  multiple  images  have been put into a single archive (for example,
       .tar), the Delta filter will work on that too as	 long  as  all	images
       have the same number of bytes per pixel.

SEE ALSO
       xzdec(1),   xzdiff(1),	xzgrep(1),   xzless(1),	  xzmore(1),  gzip(1),
       bzip2(1), 7z(1)

       XZ Utils: <https://tukaani.org/xz/>
       XZ Embedded: <https://tukaani.org/xz/embedded.html>
       LZMA SDK: <https://7-zip.org/sdk.html>



Tukaani				  2024-12-30				 XZ(1)

LZMAINFO(1)			   XZ Utils			   LZMAINFO(1)



NAME
       lzmainfo - show information stored in the .lzma file header

SYNOPSIS
       lzmainfo [--help] [--version] [file...]

DESCRIPTION
       lzmainfo	 shows	information stored in the .lzma file header.  It reads
       the first 13 bytes from the specified file,  decodes  the  header,  and
       prints it to standard output in human readable format.  If no files are
       given or file is -, standard input is read.

       Usually the most interesting information is the uncompressed  size  and
       the  dictionary	size.  Uncompressed size can be shown only if the file
       is in the non-streamed .lzma format variant.  The amount of memory  re‐
       quired to decompress the file is a few dozen kilobytes plus the dictio‐
       nary size.

       lzmainfo is included in XZ Utils primarily for  backward	 compatibility
       with LZMA Utils.

EXIT STATUS
       0      All is good.

       1      An error occurred.

BUGS
       lzmainfo	 uses  MB  while the correct suffix would be MiB (2^20 bytes).
       This is to keep the output compatible with LZMA Utils.

SEE ALSO
       xz(1)



Tukaani				  2013-06-30			   LZMAINFO(1)

XZ(1)				   XZ Utils				 XZ(1)



NAME
       xz,  unxz,  xzcat, lzma, unlzma, lzcat - Compress or decompress .xz and
       .lzma files

SYNOPSIS
       xz [option...]  [file...]

COMMAND ALIASES
       unxz is equivalent to xz --decompress.
       xzcat is equivalent to xz --decompress --stdout.
       lzma is equivalent to xz --format=lzma.
       unlzma is equivalent to xz --format=lzma --decompress.
       lzcat is equivalent to xz --format=lzma --decompress --stdout.

       When writing scripts that need to decompress files, it  is  recommended
       to  always use the name xz with appropriate arguments (xz -d or xz -dc)
       instead of the names unxz and xzcat.

DESCRIPTION
       xz is a general-purpose data compression tool with command line	syntax
       similar	to  gzip(1)  and  bzip2(1).  The native file format is the .xz
       format, but the legacy .lzma format used by LZMA	 Utils	and  raw  com‐
       pressed	streams	 with  no container format headers are also supported.
       In addition, decompression of the .lz format used by lzip is supported.

       xz compresses or decompresses each file according to the selected oper‐
       ation mode.  If no files are given or file is -, xz reads from standard
       input and writes the processed data to standard output.	xz will refuse
       (display	 an error and skip the file) to write compressed data to stan‐
       dard output if it is a terminal.	 Similarly, xz	will  refuse  to  read
       compressed data from standard input if it is a terminal.

       Unless  --stdout	 is specified, files other than - are written to a new
       file whose name is derived from the source file name:

       •  When compressing, the suffix of  the	target	file  format  (.xz  or
	  .lzma)  is  appended	to the source filename to get the target file‐
	  name.

       •  When decompressing, the .xz, .lzma, or .lz suffix  is	 removed  from
	  the  filename	 to  get  the target filename.	xz also recognizes the
	  suffixes .txz and .tlz, and replaces them with the .tar suffix.

       If the target file already exists, an error is displayed and  the  file
       is skipped.

       Unless  writing	to standard output, xz will display a warning and skip
       the file if any of the following applies:

       •  File is not a regular file.  Symbolic links are  not	followed,  and
	  thus they are not considered to be regular files.

       •  File has more than one hard link.

       •  File has setuid, setgid, or sticky bit set.

       •  The  operation  mode	is  set to compress and the file already has a
	  suffix of the target file format (.xz or .txz	 when  compressing  to
	  the .xz format, and .lzma or .tlz when compressing to the .lzma for‐
	  mat).

       •  The operation mode is set to decompress and the file doesn't have  a
	  suffix of any of the supported file formats (.xz, .txz, .lzma, .tlz,
	  or .lz).

       After successfully compressing or decompressing the file, xz copies the
       owner,  group, permissions, access time, and modification time from the
       source file to the target file.	If copying the group fails,  the  per‐
       missions are modified so that the target file doesn't become accessible
       to users who didn't have permission to  access  the  source  file.   xz
       doesn't support copying other metadata like access control lists or ex‐
       tended attributes yet.

       Once the target file has been successfully closed, the source  file  is
       removed	unless --keep was specified.  The source file is never removed
       if the output is written to standard output or if an error occurs.

       Sending SIGINFO or SIGUSR1 to the xz process makes  it  print  progress
       information  to	standard  error.  This has only limited use since when
       standard error is a terminal, using --verbose will display an automati‐
       cally updating progress indicator.

   Memory usage
       The  memory  usage of xz varies from a few hundred kilobytes to several
       gigabytes depending on the compression  settings.   The	settings  used
       when compressing a file determine the memory requirements of the decom‐
       pressor.	 Typically the decompressor needs 5 % to 20 % of the amount of
       memory that the compressor needed when creating the file.  For example,
       decompressing a file created with xz -9 currently  requires  65 MiB  of
       memory.	 Still,	 it is possible to have .xz files that require several
       gigabytes of memory to decompress.

       Especially users of older systems may  find  the	 possibility  of  very
       large  memory  usage  annoying.	To prevent uncomfortable surprises, xz
       has a built-in memory usage limiter,  which  is	disabled  by  default.
       While  some operating systems provide ways to limit the memory usage of
       processes, relying on it wasn't deemed to be flexible enough (for exam‐
       ple, using ulimit(1) to limit virtual memory tends to cripple mmap(2)).

       The  memory  usage  limiter can be enabled with the command line option
       --memlimit=limit.  Often it is more convenient to enable the limiter by
       default	by  setting the environment variable XZ_DEFAULTS, for example,
       XZ_DEFAULTS=--memlimit=150MiB.  It is possible to set the limits	 sepa‐
       rately  for  compression	 and  decompression  by	 using --memlimit-com‐
       press=limit and --memlimit-decompress=limit.  Using these  two  options
       outside	XZ_DEFAULTS is rarely useful because a single run of xz cannot
       do both compression  and	 decompression	and  --memlimit=limit  (or  -M
       limit) is shorter to type on the command line.

       If  the specified memory usage limit is exceeded when decompressing, xz
       will display an error and decompressing the file	 will  fail.   If  the
       limit  is  exceeded when compressing, xz will try to scale the settings
       down so that the limit is no longer exceeded (except when using	--for‐
       mat=raw	or --no-adjust).  This way the operation won't fail unless the
       limit is very small.  The scaling of the settings is done in steps that
       don't match the compression level presets, for example, if the limit is
       only slightly less than the amount required for	xz  -9,	 the  settings
       will be scaled down only a little, not all the way down to xz -8.

   Concatenation and padding with .xz files
       It is possible to concatenate .xz files as is.  xz will decompress such
       files as if they were a single .xz file.

       It is possible to insert padding between the concatenated parts or  af‐
       ter the last part.  The padding must consist of null bytes and the size
       of the padding must be a multiple of four bytes.	 This can  be  useful,
       for  example,  if the .xz file is stored on a medium that measures file
       sizes in 512-byte blocks.

       Concatenation and padding are not  allowed  with	 .lzma	files  or  raw
       streams.

OPTIONS
   Integer suffixes and special values
       In  most places where an integer argument is expected, an optional suf‐
       fix is supported to easily indicate large integers.  There must	be  no
       space between the integer and the suffix.

       KiB    Multiply	the integer by 1,024 (2^10).  Ki, k, kB, K, and KB are
	      accepted as synonyms for KiB.

       MiB    Multiply the integer by 1,048,576 (2^20).	 Mi, m, M, and MB  are
	      accepted as synonyms for MiB.

       GiB    Multiply	the integer by 1,073,741,824 (2^30).  Gi, g, G, and GB
	      are accepted as synonyms for GiB.

       The special value max can be used to indicate the maximum integer value
       supported by the option.

   Operation mode
       If  multiple  operation	mode options are given, the last one takes ef‐
       fect.

       -z, --compress
	      Compress.	 This is the default operation mode when no  operation
	      mode  option is specified and no other operation mode is implied
	      from the command name (for example, unxz implies --decompress).

	      After successful compression, the source file is removed	unless
	      writing to standard output or --keep was specified.

       -d, --decompress, --uncompress
	      Decompress.   After successful decompression, the source file is
	      removed unless writing to standard output or --keep  was	speci‐
	      fied.

       -t, --test
	      Test  the integrity of compressed files.	This option is equiva‐
	      lent to --decompress --stdout except that the decompressed  data
	      is  discarded  instead  of being written to standard output.  No
	      files are created or removed.

       -l, --list
	      Print information about compressed files.	 No uncompressed  out‐
	      put  is  produced, and no files are created or removed.  In list
	      mode, the program cannot read the compressed data from  standard
	      input or from other unseekable sources.

	      The  default  listing  shows  basic information about files, one
	      file per line.  To get more detailed information, use  also  the
	      --verbose	 option.   For	even  more  information, use --verbose
	      twice, but note that this may be slow, because getting  all  the
	      extra  information  requires  many  seeks.  The width of verbose
	      output exceeds 80 characters, so piping the output to, for exam‐
	      ple,  less -S  may  be  convenient  if  the  terminal isn't wide
	      enough.

	      The exact output may vary between xz versions and different  lo‐
	      cales.   For  machine-readable  output, --robot --list should be
	      used.

   Operation modifiers
       -k, --keep
	      Don't delete the input files.

	      Since xz 5.2.6, this option also makes xz compress or decompress
	      even if the input is a symbolic link to a regular file, has more
	      than one hard link, or has the setuid,  setgid,  or  sticky  bit
	      set.   The setuid, setgid, and sticky bits are not copied to the
	      target file.  In	earlier	 versions  this	 was  only  done  with
	      --force.

       -f, --force
	      This option has several effects:

	      •	 If the target file already exists, delete it before compress‐
		 ing or decompressing.

	      •	 Compress or decompress even if the input is a	symbolic  link
		 to  a	regular	 file, has more than one hard link, or has the
		 setuid, setgid, or sticky bit set.  The setuid,  setgid,  and
		 sticky bits are not copied to the target file.

	      •	 When  used with --decompress --stdout and xz cannot recognize
		 the type of the source file, copy the source file  as	is  to
		 standard  output.   This allows xzcat --force to be used like
		 cat(1) for files that have not been compressed with xz.  Note
		 that in future, xz might support new compressed file formats,
		 which may make xz decompress more types of files  instead  of
		 copying  them	as is to standard output.  --format=format can
		 be used to restrict xz to decompress only a single file  for‐
		 mat.

       -c, --stdout, --to-stdout
	      Write the compressed or decompressed data to standard output in‐
	      stead of a file.	This implies --keep.

       --single-stream
	      Decompress only the first .xz stream, and silently ignore possi‐
	      ble  remaining  input  data following the stream.	 Normally such
	      trailing garbage makes xz display an error.

	      xz never decompresses more than one stream from .lzma  files  or
	      raw  streams, but this option still makes xz ignore the possible
	      trailing data after the .lzma file or raw stream.

	      This option has no effect if the operation mode is not  --decom‐
	      press or --test.

       --no-sparse
	      Disable  creation of sparse files.  By default, if decompressing
	      into a regular file, xz tries to make the file sparse if the de‐
	      compressed  data	contains  long	sequences of binary zeros.  It
	      also works when writing to standard output as long  as  standard
	      output  is  connected  to	 a regular file and certain additional
	      conditions are met to make it safe.  Creating sparse  files  may
	      save  disk  space and speed up the decompression by reducing the
	      amount of disk I/O.

       -S .suf, --suffix=.suf
	      When compressing, use .suf as the suffix for the target file in‐
	      stead  of	 .xz  or .lzma.	 If not writing to standard output and
	      the source file already has the suffix .suf, a warning  is  dis‐
	      played and the file is skipped.

	      When  decompressing, recognize files with the suffix .suf in ad‐
	      dition to files with the .xz, .txz, .lzma, .tlz, or .lz  suffix.
	      If the source file has the suffix .suf, the suffix is removed to
	      get the target filename.

	      When compressing or decompressing	 raw  streams  (--format=raw),
	      the  suffix  must always be specified unless writing to standard
	      output, because there is no default suffix for raw streams.

       --files[=file]
	      Read the filenames to process from file;	if  file  is  omitted,
	      filenames	 are read from standard input.	Filenames must be ter‐
	      minated with the newline character.  A dash (-) is  taken	 as  a
	      regular  filename; it doesn't mean standard input.  If filenames
	      are given also as command line arguments, they are processed be‐
	      fore the filenames read from file.

       --files0[=file]
	      This  is	identical  to --files[=file] except that each filename
	      must be terminated with the null character.

   Basic file format and compression options
       -F format, --format=format
	      Specify the file format to compress or decompress:

	      auto   This is the default.  When compressing, auto  is  equiva‐
		     lent  to xz.  When decompressing, the format of the input
		     file is automatically detected.  Note  that  raw  streams
		     (created with --format=raw) cannot be auto-detected.

	      xz     Compress to the .xz file format, or accept only .xz files
		     when decompressing.

	      lzma, alone
		     Compress to the legacy .lzma file format, or accept  only
		     .lzma  files  when	 decompressing.	  The alternative name
		     alone is provided for backwards compatibility  with  LZMA
		     Utils.

	      lzip   Accept only .lz files when decompressing.	Compression is
		     not supported.

		     The .lz format version 0 and the unextended version 1 are
		     supported.	 Version 0 files were produced by lzip 1.3 and
		     older.  Such files aren't common but may  be  found  from
		     file  archives  as a few source packages were released in
		     this format.  People might have  old  personal  files  in
		     this  format  too.	  Decompression support for the format
		     version 0 was removed in lzip 1.18.

		     lzip 1.4 and later create files in the format version  1.
		     The  sync	flush marker extension to the format version 1
		     was added in lzip 1.6.  This extension is rarely used and
		     isn't supported by xz (diagnosed as corrupt input).

	      raw    Compress  or  uncompress a raw stream (no headers).  This
		     is meant for advanced users only.	To decode raw streams,
		     you need use --format=raw and explicitly specify the fil‐
		     ter chain, which normally would have been stored  in  the
		     container headers.

       -C check, --check=check
	      Specify  the  type  of the integrity check.  The check is calcu‐
	      lated from the uncompressed data and stored  in  the  .xz	 file.
	      This  option  has	 an  effect only when compressing into the .xz
	      format; the .lzma format doesn't support integrity checks.   The
	      integrity check (if any) is verified when the .xz file is decom‐
	      pressed.

	      Supported check types:

	      none   Don't calculate an integrity check at all.	 This is  usu‐
		     ally  a  bad  idea.  This can be useful when integrity of
		     the data is verified by other means anyway.

	      crc32  Calculate CRC32  using  the  polynomial  from  IEEE-802.3
		     (Ethernet).

	      crc64  Calculate CRC64 using the polynomial from ECMA-182.  This
		     is the default, since it is slightly better than CRC32 at
		     detecting	damaged files and the speed difference is neg‐
		     ligible.

	      sha256 Calculate SHA-256.	 This is somewhat  slower  than	 CRC32
		     and CRC64.

	      Integrity	 of the .xz headers is always verified with CRC32.  It
	      is not possible to change or disable it.

       --ignore-check
	      Don't verify the integrity check of the compressed data when de‐
	      compressing.   The CRC32 values in the .xz headers will still be
	      verified normally.

	      Do not use this option unless you know what you are doing.  Pos‐
	      sible reasons to use this option:

	      •	 Trying to recover data from a corrupt .xz file.

	      •	 Speeding  up decompression.  This matters mostly with SHA-256
		 or with files that have compressed extremely well.  It's rec‐
		 ommended  to  not use this option for this purpose unless the
		 file integrity is verified externally in some other way.

       -0 ... -9
	      Select a compression preset level.  The default is -6.  If  mul‐
	      tiple  preset  levels  are specified, the last one takes effect.
	      If a custom filter chain was already specified, setting  a  com‐
	      pression preset level clears the custom filter chain.

	      The  differences	between	 the presets are more significant than
	      with gzip(1) and bzip2(1).  The  selected	 compression  settings
	      determine	 the memory requirements of the decompressor, thus us‐
	      ing a too high preset level might make it painful to  decompress
	      the  file	 on an old system with little RAM.  Specifically, it's
	      not a good idea to blindly use -9 for everything like  it	 often
	      is with gzip(1) and bzip2(1).

	      -0 ... -3
		     These  are somewhat fast presets.	-0 is sometimes faster
		     than gzip -9 while compressing much better.   The	higher
		     ones  often have speed comparable to bzip2(1) with compa‐
		     rable or better compression ratio, although  the  results
		     depend a lot on the type of data being compressed.

	      -4 ... -6
		     Good  to very good compression while keeping decompressor
		     memory usage reasonable even for old systems.  -6 is  the
		     default,  which is usually a good choice for distributing
		     files that need to be decompressible even on systems with
		     only  16 MiB  RAM.	  (-5e or -6e may be worth considering
		     too.  See --extreme.)

	      -7 ... -9
		     These are like -6 but with higher compressor  and	decom‐
		     pressor  memory requirements.  These are useful only when
		     compressing files bigger than 8 MiB, 16 MiB, and  32 MiB,
		     respectively.

	      On the same hardware, the decompression speed is approximately a
	      constant number of bytes of  compressed  data  per  second.   In
	      other  words,  the better the compression, the faster the decom‐
	      pression will usually be.	 This also means that  the  amount  of
	      uncompressed output produced per second can vary a lot.

	      The following table summarises the features of the presets:

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem -0;256 KiB;0;3 MiB;1 MiB -1;1 MiB;1;9
		     MiB;2 MiB -2;2 MiB;2;17 MiB;3 MiB -3;4 MiB;3;32 MiB;5 MiB
		     -4;4 MiB;4;48 MiB;5 MiB  -5;8  MiB;5;94  MiB;9  MiB  -6;8
		     MiB;6;94  MiB;9  MiB  -7;16  MiB;6;186  MiB;17  MiB -8;32
		     MiB;6;370 MiB;33 MiB -9;64 MiB;6;674 MiB;65 MiB

	      Column descriptions:

	      •	 DictSize is the LZMA2 dictionary size.	 It is waste of memory
		 to  use a dictionary bigger than the size of the uncompressed
		 file.	This is why it is good to avoid using the  presets  -7
		 ...  -9 when there's no real need for them.  At -6 and lower,
		 the amount of memory wasted is usually low enough to not mat‐
		 ter.

	      •	 CompCPU  is a simplified representation of the LZMA2 settings
		 that affect compression speed.	 The dictionary	 size  affects
		 speed too, so while CompCPU is the same for levels -6 ... -9,
		 higher levels still tend to be a little slower.  To get  even
		 slower and thus possibly better compression, see --extreme.

	      •	 CompMem  contains  the	 compressor memory requirements in the
		 single-threaded mode.	It may vary slightly between  xz  ver‐
		 sions.

	      •	 DecMem	 contains  the decompressor memory requirements.  That
		 is, the compression settings determine	 the  memory  require‐
		 ments of the decompressor.  The exact decompressor memory us‐
		 age is slightly more than the LZMA2 dictionary size, but  the
		 values	 in  the  table	 have been rounded up to the next full
		 MiB.

	      Memory requirements of the multi-threaded mode are significantly
	      higher  than that of the single-threaded mode.  With the default
	      value of --block-size, each thread needs 3*3*DictSize plus Comp‐
	      Mem  or  DecMem.	For example, four threads with preset -6 needs
	      660–670 MiB of memory.

       -e, --extreme
	      Use a slower variant of the selected  compression	 preset	 level
	      (-0 ... -9) to hopefully get a little bit better compression ra‐
	      tio, but with bad luck this can also make it worse.   Decompres‐
	      sor  memory  usage  is not affected, but compressor memory usage
	      increases a little at preset levels -0 ... -3.

	      Since there are two presets  with	 dictionary  sizes  4 MiB  and
	      8 MiB,  the  presets  -3e	 and  -5e use slightly faster settings
	      (lower CompCPU) than -4e and -6e, respectively.  That way no two
	      presets are identical.

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem  -0e;256  KiB;8;4  MiB;1  MiB	 -1e;1
		     MiB;8;13	MiB;2  MiB  -2e;2  MiB;8;25  MiB;3  MiB	 -3e;4
		     MiB;7;48  MiB;5  MiB  -4e;4  MiB;8;48  MiB;5  MiB	 -5e;8
		     MiB;7;94  MiB;9  MiB  -6e;8  MiB;8;94  MiB;9  MiB	-7e;16
		     MiB;8;186 MiB;17 MiB -8e;32 MiB;8;370 MiB;33  MiB	-9e;64
		     MiB;8;674 MiB;65 MiB

	      For  example,  there  are a total of four presets that use 8 MiB
	      dictionary, whose order from the fastest to the slowest  is  -5,
	      -6, -5e, and -6e.

       --fast
       --best These  are  somewhat  misleading	aliases for -0 and -9, respec‐
	      tively.  These are provided  only	 for  backwards	 compatibility
	      with LZMA Utils.	Avoid using these options.

       --block-size=size
	      When  compressing	 to  the .xz format, split the input data into
	      blocks of size bytes.  The blocks are  compressed	 independently
	      from each other, which helps with multi-threading and makes lim‐
	      ited random-access decompression possible.  This option is typi‐
	      cally  used to override the default block size in multi-threaded
	      mode, but this option can be used in single-threaded mode too.

	      In multi-threaded mode about three times size bytes will be  al‐
	      located  in each thread for buffering input and output.  The de‐
	      fault size is three times the LZMA2 dictionary size  or  1  MiB,
	      whichever is more.  Typically a good value is 2–4 times the size
	      of the LZMA2 dictionary or at least 1 MiB.  Using size less than
	      the LZMA2 dictionary size is waste of RAM because then the LZMA2
	      dictionary buffer will never get fully used.  In	multi-threaded
	      mode,  the  sizes of the blocks are stored in the block headers.
	      This size information is required for multi-threaded  decompres‐
	      sion.

	      In  single-threaded  mode no block splitting is done by default.
	      Setting this option doesn't affect memory usage.	No size infor‐
	      mation is stored in block headers, thus files created in single-
	      threaded mode won't be identical	to  files  created  in	multi-
	      threaded	mode.  The lack of size information also means that xz
	      won't be able decompress the files in multi-threaded mode.

       --block-list=items
	      When compressing to the .xz format, start a new  block  with  an
	      optional custom filter chain after the given intervals of uncom‐
	      pressed data.

	      The items are a comma-separated list.  Each item consists of  an
	      optional filter chain number between 0 and 9 followed by a colon
	      (:) and a required size of uncompressed data.  Omitting an  item
	      (two  or more consecutive commas) is a shorthand to use the size
	      and filters of the previous item.

	      If the input file is bigger than the sum of the sizes in	items,
	      the  last item is repeated until the end of the file.  A special
	      value of 0 may be used as the last size  to  indicate  that  the
	      rest of the file should be encoded as a single block.

	      An  alternative  filter chain for each block can be specified in
	      combination with the --filters1=filters  ...  --filters9=filters
	      options.	 These options define filter chains with an identifier
	      between 1–9.  Filter chain 0 can be used to refer to the default
	      filter  chain,  which  is	 the  same  as not specifying a filter
	      chain.  The filter chain identifier can be used before  the  un‐
	      compressed  size,	 followed by a colon (:).  For example, if one
	      specifies	 --block-list=1:2MiB,3:2MiB,2:4MiB,,2MiB,0:4MiB	  then
	      blocks will be created using:

	      •	 The filter chain specified by --filters1 and 2 MiB input

	      •	 The filter chain specified by --filters3 and 2 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The default filter chain and 2 MiB input

	      •	 The  default filter chain and 4 MiB input for every block un‐
		 til end of input.

	      If one specifies a size that exceeds the	encoder's  block  size
	      (either  the  default value in threaded mode or the value speci‐
	      fied with --block-size=size), the encoder will create additional
	      blocks while keeping the boundaries specified in items.  For ex‐
	      ample,	  if	  one	    specifies	    --block-size=10MiB
	      --block-list=5MiB,10MiB,8MiB,12MiB,24MiB	and  the input file is
	      80 MiB, one will get 11 blocks: 5, 10, 8, 10, 2, 10, 10, 4,  10,
	      10, and 1 MiB.

	      In multi-threaded mode the sizes of the blocks are stored in the
	      block headers.  This isn't done in single-threaded mode, so  the
	      encoded  output won't be identical to that of the multi-threaded
	      mode.

       --flush-timeout=timeout
	      When compressing, if more than timeout milliseconds (a  positive
	      integer)	has  passed  since the previous flush and reading more
	      input would block, all the pending input data  is	 flushed  from
	      the  encoder  and made available in the output stream.  This can
	      be useful if xz is used to compress data that is streamed over a
	      network.	 Small	timeout	 values make the data available at the
	      receiving end with a small delay, but large timeout values  give
	      better compression ratio.

	      This  feature  is disabled by default.  If this option is speci‐
	      fied more than once, the last one	 takes	effect.	  The  special
	      timeout  value  of 0 can be used to explicitly disable this fea‐
	      ture.

	      This feature is not available on non-POSIX systems.

	      This feature is still experimental.  Currently xz is  unsuitable
	      for  decompressing  the  stream  in real time due to how xz does
	      buffering.

       --memlimit-compress=limit
	      Set a memory usage limit for compression.	  If  this  option  is
	      specified multiple times, the last one takes effect.

	      If the compression settings exceed the limit, xz will attempt to
	      adjust the settings downwards so that the limit is no longer ex‐
	      ceeded  and display a notice that automatic adjustment was done.
	      The adjustments are done in this order: reducing the  number  of
	      threads, switching to single-threaded mode if even one thread in
	      multi-threaded mode exceeds the limit, and finally reducing  the
	      LZMA2 dictionary size.

	      When  compressing	 with  --format=raw or if --no-adjust has been
	      specified, only the number of threads may be  reduced  since  it
	      can be done without affecting the compressed output.

	      If  the  limit cannot be met even with the adjustments described
	      above, an error is displayed and xz will exit with  exit	status
	      1.

	      The limit can be specified in multiple ways:

	      •	 The  limit can be an absolute value in bytes.	Using an inte‐
		 ger suffix like MiB can be useful.  Example:  --memlimit-com‐
		 press=80MiB

	      •	 The  limit can be specified as a percentage of total physical
		 memory (RAM).	This can be useful especially when setting the
		 XZ_DEFAULTS  environment  variable  in a shell initialization
		 script that is shared between different computers.  That  way
		 the  limit  is automatically bigger on systems with more mem‐
		 ory.  Example: --memlimit-compress=70%

	      •	 The limit can be reset back to its default value  by  setting
		 it  to	 0.  This is currently equivalent to setting the limit
		 to max (no memory usage limit).

	      For 32-bit xz there is a special case: if	 the  limit  would  be
	      over 4020 MiB, the limit is set to 4020 MiB.  On MIPS32 2000 MiB
	      is used instead.	(The values 0 and max aren't affected by this.
	      A similar feature doesn't exist for decompression.)  This can be
	      helpful when a 32-bit executable has  access  to	4 GiB  address
	      space  (2	 GiB on MIPS32) while hopefully doing no harm in other
	      situations.

	      See also the section Memory usage.

       --memlimit-decompress=limit
	      Set a memory usage limit for decompression.  This	 also  affects
	      the  --list  mode.  If the operation is not possible without ex‐
	      ceeding the limit, xz will display an  error  and	 decompressing
	      the  file will fail.  See --memlimit-compress=limit for possible
	      ways to specify the limit.

       --memlimit-mt-decompress=limit
	      Set a memory usage limit for multi-threaded decompression.  This
	      can  only	 affect the number of threads; this will never make xz
	      refuse to decompress a file.  If limit is too low to  allow  any
	      multi-threading,	the  limit  is ignored and xz will continue in
	      single-threaded mode.  Note that if  also	 --memlimit-decompress
	      is used, it will always apply to both single-threaded and multi-
	      threaded modes, and so the effective limit  for  multi-threading
	      will  never  be higher than the limit set with --memlimit-decom‐
	      press.

	      In contrast to the other	memory	usage  limit  options,	--mem‐
	      limit-mt-decompress=limit	 has  a system-specific default limit.
	      xz --info-memory can be used to see the current value.

	      This option and its default  value  exist	 because  without  any
	      limit  the  threaded decompressor could end up allocating an in‐
	      sane amount of memory with some input  files.   If  the  default
	      limit is too low on your system, feel free to increase the limit
	      but never set it to a value larger than the amount of usable RAM
	      as  with	appropriate  input  files  xz will attempt to use that
	      amount of memory even with a low number of threads.  Running out
	      of  memory  or  swapping	will not improve decompression perfor‐
	      mance.

	      See --memlimit-compress=limit for possible ways to  specify  the
	      limit.   Setting limit to 0 resets the limit to the default sys‐
	      tem-specific value.

       -M limit, --memlimit=limit, --memory=limit
	      This  is	equivalent  to	specifying   --memlimit-compress=limit
	      --memlimit-decompress=limit --memlimit-mt-decompress=limit.

       --no-adjust
	      Display  an  error  and exit if the memory usage limit cannot be
	      met without adjusting settings that affect the  compressed  out‐
	      put.   That is, this prevents xz from switching the encoder from
	      multi-threaded mode to single-threaded mode  and	from  reducing
	      the  LZMA2  dictionary  size.  Even when this option is used the
	      number of threads may be reduced to meet the memory usage	 limit
	      as that won't affect the compressed output.

	      Automatic adjusting is always disabled when creating raw streams
	      (--format=raw).

       -T threads, --threads=threads
	      Specify the number of worker threads to use.  Setting threads to
	      a special value 0 makes xz use up to as many threads as the pro‐
	      cessor(s) on the system support.	The actual number  of  threads
	      can  be  fewer  than threads if the input file is not big enough
	      for threading with the given settings or if using	 more  threads
	      would exceed the memory usage limit.

	      The  single-threaded and multi-threaded compressors produce dif‐
	      ferent output.  Single-threaded compressor will give the	small‐
	      est  file	 size but only the output from the multi-threaded com‐
	      pressor can be decompressed  using  multiple  threads.   Setting
	      threads to 1 will use the single-threaded mode.  Setting threads
	      to any other value, including 0,	will  use  the	multi-threaded
	      compressor even if the system supports only one hardware thread.
	      (xz 5.2.x used single-threaded mode in this situation.)

	      To use multi-threaded mode with only one thread, set threads  to
	      +1.   The	 +  prefix  has no effect with values other than 1.  A
	      memory usage limit can still make xz switch  to  single-threaded
	      mode  unless  --no-adjust is used.  Support for the + prefix was
	      added in xz 5.4.0.

	      If an automatic number of threads has been requested and no mem‐
	      ory  usage  limit has been specified, then a system-specific de‐
	      fault soft limit will be used to possibly limit  the  number  of
	      threads.	 It is a soft limit in sense that it is ignored if the
	      number of threads becomes one, thus a soft limit will never stop
	      xz  from	compressing or decompressing.  This default soft limit
	      will not make xz switch  from  multi-threaded  mode  to  single-
	      threaded	 mode.	  The  active  limits  can  be	seen  with  xz
	      --info-memory.

	      Currently the only threading method is to split the  input  into
	      blocks and compress them independently from each other.  The de‐
	      fault block size depends on the compression  level  and  can  be
	      overridden with the --block-size=size option.

	      Threaded decompression only works on files that contain multiple
	      blocks with size information in block headers.  All large enough
	      files compressed in multi-threaded mode meet this condition, but
	      files  compressed	 in  single-threaded  mode   don't   even   if
	      --block-size=size has been used.

	      The  default  value for threads is 0.  In xz 5.4.x and older the
	      default is 1.

   Custom compressor filter chains
       A custom filter chain allows specifying the compression settings in de‐
       tail  instead  of  relying  on  the settings associated to the presets.
       When a custom filter chain is specified, preset options (-0 ... -9  and
       --extreme)  earlier on the command line are forgotten.  If a preset op‐
       tion is specified after one or more custom filter  chain	 options,  the
       new  preset  takes effect and the custom filter chain options specified
       earlier are forgotten.

       A filter chain is comparable to piping on the command line.  When  com‐
       pressing, the uncompressed input goes to the first filter, whose output
       goes to the next filter (if any).  The output of the last  filter  gets
       written	to  the compressed file.  The maximum number of filters in the
       chain is four, but typically a filter chain has only one	 or  two  fil‐
       ters.

       Many filters have limitations on where they can be in the filter chain:
       some filters can work only as the last filter in the chain,  some  only
       as  a non-last filter, and some work in any position in the chain.  De‐
       pending on the filter, this limitation is either inherent to the filter
       design or exists to prevent security issues.

       A  custom filter chain can be specified in two different ways.  The op‐
       tions --filters=filters and --filters1=filters  ...  --filters9=filters
       allow specifying an entire filter chain in one option using the liblzma
       filter string syntax.  Alternatively, a filter chain can	 be  specified
       by  using  one  or more individual filter options in the order they are
       wanted in the filter chain.  That is, the order of the individual  fil‐
       ter  options is significant!  When decoding raw streams (--format=raw),
       the filter chain must be specified in the same order as it  was	speci‐
       fied  when compressing.	Any individual filter or preset options speci‐
       fied before the full chain option (--filters=filters) will  be  forgot‐
       ten.  Individual filters specified after the full chain option will re‐
       set the filter chain.

       Both the full and individual filter options  take  filter-specific  op‐
       tions  as a comma-separated list.  Extra commas in options are ignored.
       Every option has a default value, so specify those you want to change.

       To see the whole filter chain and options, use xz  -vv  (that  is,  use
       --verbose twice).  This works also for viewing the filter chain options
       used by presets.

       --filters=filters
	      Specify the full filter chain or a preset in  a  single  option.
	      Each filter can be separated by spaces or two dashes (--).  fil‐
	      ters may need to be quoted on the shell command line  so	it  is
	      parsed  as  a  single option.  To denote options, use : or =.  A
	      preset can be prefixed with a - and followed with zero  or  more
	      flags.   The  only supported flag is e to apply the same options
	      as --extreme.

       --filters1=filters ... --filters9=filters
	      Specify up to nine additional filter chains  that	 can  be  used
	      with --block-list.

	      For  example,  when compressing an archive with executable files
	      followed by text files, the executable part could use  a	filter
	      chain with a BCJ filter and the text part only the LZMA2 filter.

       --filters-help
	      Display  a  help	message	 describing how to specify presets and
	      custom filter chains in the --filters and --filters1=filters ...
	      --filters9=filters options, and exit successfully.

       --lzma1[=options]
       --lzma2[=options]
	      Add  LZMA1  or  LZMA2 filter to the filter chain.	 These filters
	      can be used only as the last filter in the chain.

	      LZMA1 is a legacy filter, which is supported almost  solely  due
	      to  the  legacy  .lzma  file  format, which supports only LZMA1.
	      LZMA2 is an updated version of LZMA1 to fix some	practical  is‐
	      sues  of	LZMA1.	 The .xz format uses LZMA2 and doesn't support
	      LZMA1 at all.  Compression speed and ratios of LZMA1  and	 LZMA2
	      are practically the same.

	      LZMA1 and LZMA2 share the same set of options:

	      preset=preset
		     Reset  all LZMA1 or LZMA2 options to preset.  Preset con‐
		     sist of an integer, which may be followed by  single-let‐
		     ter  preset  modifiers.   The integer can be from 0 to 9,
		     matching the command line options -0 ...  -9.   The  only
		     supported	modifier  is  currently e, which matches --ex‐
		     treme.  If no preset is specified, the default values  of
		     LZMA1 or LZMA2 options are taken from the preset 6.

	      dict=size
		     Dictionary (history buffer) size indicates how many bytes
		     of the recently processed uncompressed data  is  kept  in
		     memory.   The  algorithm tries to find repeating byte se‐
		     quences (matches) in the uncompressed data,  and  replace
		     them with references to the data currently in the dictio‐
		     nary.  The bigger	the  dictionary,  the  higher  is  the
		     chance to find a match.  Thus, increasing dictionary size
		     usually improves compression ratio, but a dictionary big‐
		     ger than the uncompressed file is waste of memory.

		     Typical  dictionary  size	is from 64 KiB to 64 MiB.  The
		     minimum is 4 KiB.	The maximum for	 compression  is  cur‐
		     rently 1.5 GiB (1536 MiB).	 The decompressor already sup‐
		     ports dictionaries up to one byte less than 4 GiB,	 which
		     is the maximum for the LZMA1 and LZMA2 stream formats.

		     Dictionary	 size and match finder (mf) together determine
		     the memory usage of the LZMA1 or LZMA2 encoder.  The same
		     (or bigger) dictionary size is required for decompressing
		     that was used when compressing, thus the memory usage  of
		     the  decoder  is  determined  by the dictionary size used
		     when compressing.	The .xz headers store  the  dictionary
		     size  either  as 2^n or 2^n + 2^(n-1), so these sizes are
		     somewhat preferred for compression.  Other sizes will get
		     rounded up when stored in the .xz headers.

	      lc=lc  Specify  the number of literal context bits.  The minimum
		     is 0 and the maximum is 4; the default is	3.   In	 addi‐
		     tion, the sum of lc and lp must not exceed 4.

		     All  bytes	 that cannot be encoded as matches are encoded
		     as literals.  That is, literals are  simply  8-bit	 bytes
		     that are encoded one at a time.

		     The  literal  coding makes an assumption that the highest
		     lc bits of the previous uncompressed byte correlate  with
		     the  next byte.  For example, in typical English text, an
		     upper-case letter is often followed by a lower-case  let‐
		     ter,  and	a lower-case letter is usually followed by an‐
		     other lower-case letter.  In the US-ASCII character  set,
		     the highest three bits are 010 for upper-case letters and
		     011 for lower-case letters.  When lc is at least  3,  the
		     literal coding can take advantage of this property in the
		     uncompressed data.

		     The default value (3) is usually good.  If you want maxi‐
		     mum compression, test lc=4.  Sometimes it helps a little,
		     and sometimes it makes compression worse.	If it makes it
		     worse, test lc=2 too.

	      lp=lp  Specify the number of literal position bits.  The minimum
		     is 0 and the maximum is 4; the default is 0.

		     Lp affects what kind of  alignment	 in  the  uncompressed
		     data is assumed when encoding literals.  See pb below for
		     more information about alignment.

	      pb=pb  Specify the number of position bits.  The	minimum	 is  0
		     and the maximum is 4; the default is 2.

		     Pb	 affects  what	kind  of alignment in the uncompressed
		     data is assumed in general.  The default means  four-byte
		     alignment (2^pb=2^2=4), which is often a good choice when
		     there's no better guess.

		     When the alignment is known, setting pb  accordingly  may
		     reduce  the  file	size a little.	For example, with text
		     files having one-byte  alignment  (US-ASCII,  ISO-8859-*,
		     UTF-8),  setting  pb=0  can improve compression slightly.
		     For UTF-16 text, pb=1 is a good choice.  If the alignment
		     is	 an  odd  number  like 3 bytes, pb=0 might be the best
		     choice.

		     Even though the assumed alignment can be adjusted with pb
		     and  lp,  LZMA1  and  LZMA2  still slightly favor 16-byte
		     alignment.	 It might be worth taking  into	 account  when
		     designing	file  formats that are likely to be often com‐
		     pressed with LZMA1 or LZMA2.

	      mf=mf  Match finder has a major effect on encoder speed,	memory
		     usage,  and  compression ratio.  Usually Hash Chain match
		     finders are faster than Binary Tree match	finders.   The
		     default  depends  on the preset: 0 uses hc3, 1–3 use hc4,
		     and the rest use bt4.

		     The following match finders are  supported.   The	memory
		     usage  formulas below are rough approximations, which are
		     closest to the reality when dict is a power of two.

		     hc3    Hash Chain with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 7.5 (if dict <= 16 MiB);
			    dict * 5.5 + 64 MiB (if dict > 16 MiB)

		     hc4    Hash Chain with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 7.5 (if dict <= 32 MiB);
			    dict * 6.5 (if dict > 32 MiB)

		     bt2    Binary Tree with 2-byte hashing
			    Minimum value for nice: 2
			    Memory usage: dict * 9.5

		     bt3    Binary Tree with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 11.5 (if dict <= 16 MiB);
			    dict * 9.5 + 64 MiB (if dict > 16 MiB)

		     bt4    Binary Tree with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 11.5 (if dict <= 32 MiB);
			    dict * 10.5 (if dict > 32 MiB)

	      mode=mode
		     Compression mode specifies the method to analyze the data
		     produced  by  the match finder.  Supported modes are fast
		     and normal.  The default is fast for presets 0–3 and nor‐
		     mal for presets 4–9.

		     Usually  fast  is	used with Hash Chain match finders and
		     normal with Binary Tree match finders.  This is also what
		     the presets do.

	      nice=nice
		     Specify  what  is	considered  to	be a nice length for a
		     match.  Once a match of at least nice bytes is found, the
		     algorithm stops looking for possibly better matches.

		     Nice can be 2–273 bytes.  Higher values tend to give bet‐
		     ter compression ratio at the expense of speed.   The  de‐
		     fault depends on the preset.

	      depth=depth
		     Specify  the  maximum  search  depth in the match finder.
		     The default is the special value of 0,  which  makes  the
		     compressor determine a reasonable depth from mf and nice.

		     Reasonable depth for Hash Chains is 4–100 and 16–1000 for
		     Binary Trees.  Using very high values for depth can  make
		     the  encoder  extremely slow with some files.  Avoid set‐
		     ting the depth over 1000 unless you are prepared  to  in‐
		     terrupt  the  compression	in  case  it is taking far too
		     long.

	      When decoding raw streams (--format=raw), LZMA2 needs  only  the
	      dictionary size.	LZMA1 needs also lc, lp, and pb.

       --x86[=options]
       --arm[=options]
       --armthumb[=options]
       --arm64[=options]
       --powerpc[=options]
       --ia64[=options]
       --sparc[=options]
       --riscv[=options]
	      Add  a branch/call/jump (BCJ) filter to the filter chain.	 These
	      filters can be used only as a  non-last  filter  in  the	filter
	      chain.

	      A	 BCJ filter converts relative addresses in the machine code to
	      their absolute counterparts.  This doesn't change	 the  size  of
	      the  data	 but  it increases redundancy, which can help LZMA2 to
	      produce 0–15 % smaller .xz file.	The BCJ filters are always re‐
	      versible,	 so  using a BCJ filter for wrong type of data doesn't
	      cause any data loss, although it may make the compression	 ratio
	      slightly	worse.	 The  BCJ filters are very fast and use an in‐
	      significant amount of memory.

	      These BCJ filters have known problems related to the compression
	      ratio:

	      •	 Some  types of files containing executable code (for example,
		 object files, static libraries,  and  Linux  kernel  modules)
		 have  the  addresses  in  the instructions filled with filler
		 values.  These BCJ filters will still do the address  conver‐
		 sion, which will make the compression worse with these files.

	      •	 If a BCJ filter is applied on an archive, it is possible that
		 it makes the compression ratio worse than  not	 using	a  BCJ
		 filter.   For example, if there are similar or even identical
		 executables then filtering will likely make  the  files  less
		 similar  and thus compression is worse.  The contents of non-
		 executable files in the same  archive	can  matter  too.   In
		 practice  one has to try with and without a BCJ filter to see
		 which is better in each situation.

	      Different instruction sets have different	 alignment:  the  exe‐
	      cutable  file must be aligned to a multiple of this value in the
	      input data to make the filter work.

		     tab(;); l n l l n l.  Filter;Alignment;Notes x86;1;32-bit
		     or	  64-bit  x86  ARM;4;  ARM-Thumb;2;  ARM64;4;4096-byte
		     alignment is best PowerPC;4;Big endian only IA-64;16;Ita‐
		     nium SPARC;4; RISC-V;2;

	      Since  the  BCJ-filtered	data is usually compressed with LZMA2,
	      the compression ratio may be improved slightly if the LZMA2  op‐
	      tions are set to match the alignment of the selected BCJ filter.
	      Examples:

	      •	 IA-64 filter has 16-byte alignment so pb=4,lp=4,lc=0 is  good
		 with LZMA2 (2^4=16).

	      •	 RISC-V	 code  has  2-byte  or	4-byte	alignment depending on
		 whether the file contains 16-bit compressed instructions (the
		 C   extension).    When   16-bit   instructions   are	 used,
		 pb=2,lp=1,lc=3 or pb=1,lp=1,lc=3 is good.   When  16-bit  in‐
		 structions aren't present, pb=2,lp=2,lc=2 is the best.	 read‐
		 elf -h can be used to check if "RVC" appears on  the  "Flags"
		 line.

	      •	 ARM64 is always 4-byte aligned so pb=2,lp=2,lc=2 is the best.

	      •	 The  x86  filter is an exception.  It's usually good to stick
		 to LZMA2's defaults (pb=2,lp=0,lc=3) when compressing x86 ex‐
		 ecutables.

	      All BCJ filters support the same options:

	      start=offset
		     Specify the start offset that is used when converting be‐
		     tween relative and absolute addresses.  The  offset  must
		     be a multiple of the alignment of the filter (see the ta‐
		     ble above).  The default is zero.	In practice,  the  de‐
		     fault is good; specifying a custom offset is almost never
		     useful.

       --delta[=options]
	      Add the Delta filter to the filter chain.	 The Delta filter  can
	      be only used as a non-last filter in the filter chain.

	      Currently	 only simple byte-wise delta calculation is supported.
	      It can be useful when  compressing,  for	example,  uncompressed
	      bitmap  images or uncompressed PCM audio.	 However, special pur‐
	      pose algorithms may give significantly better results than Delta
	      +	 LZMA2.	  This is true especially with audio, which compresses
	      faster and better, for example, with flac(1).

	      Supported options:

	      dist=distance
		     Specify the distance of the delta calculation  in	bytes.
		     distance must be 1–256.  The default is 1.

		     For example, with dist=2 and eight-byte input A1 B1 A2 B3
		     A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

   Other options
       -q, --quiet
	      Suppress warnings and notices.  Specify this twice  to  suppress
	      errors too.  This option has no effect on the exit status.  That
	      is, even if a warning was suppressed, the exit status  to	 indi‐
	      cate a warning is still used.

       -v, --verbose
	      Be  verbose.   If	 standard error is connected to a terminal, xz
	      will display a progress indicator.  Specifying  --verbose	 twice
	      will give even more verbose output.

	      The progress indicator shows the following information:

	      •	 Completion  percentage is shown if the size of the input file
		 is known.  That is, the percentage cannot be shown in pipes.

	      •	 Amount of compressed data produced (compressing) or  consumed
		 (decompressing).

	      •	 Amount	 of  uncompressed  data consumed (compressing) or pro‐
		 duced (decompressing).

	      •	 Compression ratio, which is calculated by dividing the amount
		 of  compressed	 data processed so far by the amount of uncom‐
		 pressed data processed so far.

	      •	 Compression or decompression speed.  This is measured as  the
		 amount	 of  uncompressed  data consumed (compression) or pro‐
		 duced (decompression) per second.  It is shown	 after	a  few
		 seconds have passed since xz started processing the file.

	      •	 Elapsed time in the format M:SS or H:MM:SS.

	      •	 Estimated  remaining  time is shown only when the size of the
		 input file is known and a  couple  of	seconds	 have  already
		 passed	 since	xz  started  processing the file.  The time is
		 shown in a less precise format which never  has  any  colons,
		 for example, 2 min 30 s.

	      When  standard  error  is not a terminal, --verbose will make xz
	      print the filename, compressed size, uncompressed size, compres‐
	      sion  ratio,  and	 possibly also the speed and elapsed time on a
	      single line to standard error after compressing or decompressing
	      the file.	 The speed and elapsed time are included only when the
	      operation took at least a few seconds.  If the operation	didn't
	      finish,  for example, due to user interruption, also the comple‐
	      tion percentage is printed if the size  of  the  input  file  is
	      known.

       -Q, --no-warn
	      Don't set the exit status to 2 even if a condition worth a warn‐
	      ing was detected.	 This  option  doesn't	affect	the  verbosity
	      level,  thus  both  --quiet and --no-warn have to be used to not
	      display warnings and to not alter the exit status.

       --robot
	      Print messages in a machine-parsable format.  This  is  intended
	      to  ease	writing	 frontends  that want to use xz instead of li‐
	      blzma, which may be the case with various scripts.   The	output
	      with  this  option  enabled  is meant to be stable across xz re‐
	      leases.  See the section ROBOT MODE for details.

       --info-memory
	      Display, in human-readable  format,  how	much  physical	memory
	      (RAM)  and  how  many processor threads xz thinks the system has
	      and the memory usage limits for compression  and	decompression,
	      and exit successfully.

       -h, --help
	      Display  a  help	message	 describing the most commonly used op‐
	      tions, and exit successfully.

       -H, --long-help
	      Display a help message describing all features of xz,  and  exit
	      successfully

       -V, --version
	      Display  the  version number of xz and liblzma in human readable
	      format.  To get machine-parsable output, specify --robot	before
	      --version.

ROBOT MODE
       The robot mode is activated with the --robot option.  It makes the out‐
       put of xz easier to parse by other programs.  Currently --robot is sup‐
       ported  only  together  with --list, --filters-help, --info-memory, and
       --version.  It will be supported for compression and  decompression  in
       the future.

   List mode
       xz --robot --list uses tab-separated output.  The first column of every
       line has a string that indicates the type of the information  found  on
       that line:

       name   This is always the first line when starting to list a file.  The
	      second column on the line is the filename.

       file   This line contains overall information about the .xz file.  This
	      line is always printed after the name line.

       stream This line type is used only when --verbose was specified.	 There
	      are as many stream lines as there are streams in the .xz file.

       block  This line type is used only when --verbose was specified.	 There
	      are  as  many  block  lines as there are blocks in the .xz file.
	      The block lines are shown after all the stream lines;  different
	      line types are not interleaved.

       summary
	      This  line type is used only when --verbose was specified twice.
	      This line is printed after all block lines.  Like the file line,
	      the  summary  line  contains  overall  information about the .xz
	      file.

       totals This line is always the very last line of the list  output.   It
	      shows the total counts and sizes.

       The columns of the file lines:
	      2.  Number of streams in the file
	      3.  Total number of blocks in the stream(s)
	      4.  Compressed size of the file
	      5.  Uncompressed size of the file
	      6.  Compression  ratio,  for  example,  0.123.  If ratio is over
		  9.999, three dashes (---) are displayed instead of  the  ra‐
		  tio.
	      7.  Comma-separated  list of integrity check names.  The follow‐
		  ing strings are used for the known check types: None, CRC32,
		  CRC64,  and  SHA-256.	 For unknown check types, Unknown-N is
		  used, where N is the Check ID as a decimal  number  (one  or
		  two digits).
	      8.  Total size of stream padding in the file

       The columns of the stream lines:
	      2.  Stream number (the first stream is 1)
	      3.  Number of blocks in the stream
	      4.  Compressed start offset
	      5.  Uncompressed start offset
	      6.  Compressed size (does not include stream padding)
	      7.  Uncompressed size
	      8.  Compression ratio
	      9.  Name of the integrity check
	      10. Size of stream padding

       The columns of the block lines:
	      2.  Number of the stream containing this block
	      3.  Block	 number	 relative  to the beginning of the stream (the
		  first block is 1)
	      4.  Block number relative to the beginning of the file
	      5.  Compressed start offset relative to  the  beginning  of  the
		  file
	      6.  Uncompressed	start  offset relative to the beginning of the
		  file
	      7.  Total compressed size of the block (includes headers)
	      8.  Uncompressed size
	      9.  Compression ratio
	      10. Name of the integrity check

       If --verbose was specified twice, additional columns  are  included  on
       the  block lines.  These are not displayed with a single --verbose, be‐
       cause getting this information requires many  seeks  and	 can  thus  be
       slow:
	      11. Value of the integrity check in hexadecimal
	      12. Block header size
	      13. Block	 flags:	 c  indicates that compressed size is present,
		  and u indicates that uncompressed size is present.   If  the
		  flag	is  not	 set,  a dash (-) is shown instead to keep the
		  string length fixed.	New flags may be added to the  end  of
		  the string in the future.
	      14. Size	of  the	 actual compressed data in the block (this ex‐
		  cludes the block header, block padding, and check fields)
	      15. Amount of memory (in	bytes)	required  to  decompress  this
		  block with this xz version
	      16. Filter  chain.   Note	 that most of the options used at com‐
		  pression time cannot be known, because only the options that
		  are needed for decompression are stored in the .xz headers.

       The columns of the summary lines:
	      2.  Amount of memory (in bytes) required to decompress this file
		  with this xz version
	      3.  yes or no indicating if all block  headers  have  both  com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      4.  Minimum xz version required to decompress the file

       The columns of the totals line:
	      2.  Number of streams
	      3.  Number of blocks
	      4.  Compressed size
	      5.  Uncompressed size
	      6.  Average compression ratio
	      7.  Comma-separated  list	 of  integrity	check  names that were
		  present in the files
	      8.  Stream padding size
	      9.  Number of files.  This is here to keep the order of the ear‐
		  lier columns the same as on file lines.

       If  --verbose  was  specified twice, additional columns are included on
       the totals line:
	      10. Maximum amount of memory (in bytes) required	to  decompress
		  the files with this xz version
	      11. yes  or  no  indicating  if all block headers have both com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      12. Minimum xz version required to decompress the file

       Future versions may add new line types and new columns can be added  to
       the existing line types, but the existing columns won't be changed.

   Filters help
       xz --robot --filters-help prints the supported filters in the following
       format:

       filter:option=<value>,option=<value>...

       filter Name of the filter

       option Name of a filter specific option

       value  Numeric value ranges appear as <min-max>.	 String value  choices
	      are shown within < > and separated by a | character.

       Each filter is printed on its own line.

   Memory limit information
       xz  --robot  --info-memory prints a single line with multiple tab-sepa‐
       rated columns:

       1.  Total amount of physical memory (RAM) in bytes.

       2.  Memory usage limit for compression in bytes	(--memlimit-compress).
	   A  special  value of 0 indicates the default setting which for sin‐
	   gle-threaded mode is the same as no limit.

       3.  Memory usage limit for decompression	 in  bytes  (--memlimit-decom‐
	   press).   A	special value of 0 indicates the default setting which
	   for single-threaded mode is the same as no limit.

       4.  Since xz 5.3.4alpha: Memory usage for multi-threaded	 decompression
	   in  bytes (--memlimit-mt-decompress).  This is never zero because a
	   system-specific default value shown in the column 5 is used	if  no
	   limit  has  been  specified explicitly.  This is also never greater
	   than the value in the column 3 even if  a  larger  value  has  been
	   specified with --memlimit-mt-decompress.

       5.  Since  xz  5.3.4alpha: A system-specific default memory usage limit
	   that is used to limit the number of threads when  compressing  with
	   an  automatic  number  of threads (--threads=0) and no memory usage
	   limit has been specified (--memlimit-compress).  This is also  used
	   as the default value for --memlimit-mt-decompress.

       6.  Since xz 5.3.4alpha: Number of available processor threads.

       In  the	future,	 the  output of xz --robot --info-memory may have more
       columns, but never more than a single line.

   Version
       xz --robot --version prints the version number of xz and liblzma in the
       following format:

       XZ_VERSION=XYYYZZZS
       LIBLZMA_VERSION=XYYYZZZS

       X      Major version.

       YYY    Minor  version.  Even numbers are stable.	 Odd numbers are alpha
	      or beta versions.

       ZZZ    Patch level for stable releases or just a counter	 for  develop‐
	      ment releases.

       S      Stability.  0 is alpha, 1 is beta, and 2 is stable.  S should be
	      always 2 when YYY is even.

       XYYYZZZS are the same on both lines if xz and liblzma are from the same
       XZ Utils release.

       Examples: 4.999.9beta is 49990091 and 5.0.0 is 50000002.

EXIT STATUS
       0      All is good.

       1      An error occurred.

       2      Something	 worth	a  warning  occurred, but no actual errors oc‐
	      curred.

       Notices (not warnings or errors) printed on standard error don't affect
       the exit status.

ENVIRONMENT
       xz  parses  space-separated lists of options from the environment vari‐
       ables XZ_DEFAULTS and XZ_OPT, in this order, before parsing the options
       from  the command line.	Note that only options are parsed from the en‐
       vironment variables; all non-options are silently ignored.  Parsing  is
       done  with getopt_long(3) which is used also for the command line argu‐
       ments.

       XZ_DEFAULTS
	      User-specific or system-wide default options.  Typically this is
	      set in a shell initialization script to enable xz's memory usage
	      limiter by default.  Excluding shell initialization scripts  and
	      similar  special	cases,	scripts must never set or unset XZ_DE‐
	      FAULTS.

       XZ_OPT This is for passing options to xz when it is not possible to set
	      the  options  directly on the xz command line.  This is the case
	      when xz is run by a script or tool, for example, GNU tar(1):

		     XZ_OPT=-2v tar caf foo.tar.xz foo

	      Scripts may use XZ_OPT, for example, to set script-specific  de‐
	      fault  compression  options.   It	 is still recommended to allow
	      users to override XZ_OPT if that is reasonable.  For example, in
	      sh(1) scripts one may use something like this:

		     XZ_OPT=${XZ_OPT-"-7e"}
		     export XZ_OPT

LZMA UTILS COMPATIBILITY
       The  command  line  syntax of xz is practically a superset of lzma, un‐
       lzma, and lzcat as found from LZMA Utils 4.32.x.	 In most cases, it  is
       possible	 to replace LZMA Utils with XZ Utils without breaking existing
       scripts.	 There are some incompatibilities though, which may  sometimes
       cause problems.

   Compression preset levels
       The  numbering  of the compression level presets is not identical in xz
       and LZMA Utils.	The most important difference is how dictionary	 sizes
       are  mapped  to different presets.  Dictionary size is roughly equal to
       the decompressor memory usage.

	      tab(;); c c c c n n.  Level;xz;LZMA Utils	 -0;256	 KiB;N/A  -1;1
	      MiB;64  KiB  -2;2 MiB;1 MiB -3;4 MiB;512 KiB -4;4 MiB;1 MiB -5;8
	      MiB;2 MiB -6;8 MiB;4 MiB -7;16 MiB;8 MiB -8;32 MiB;16 MiB	 -9;64
	      MiB;32 MiB

       The dictionary size differences affect the compressor memory usage too,
       but there are some other differences between LZMA Utils and  XZ	Utils,
       which make the difference even bigger:

	      tab(;);  c  c  c c n n.  Level;xz;LZMA Utils 4.32.x -0;3 MiB;N/A
	      -1;9 MiB;2 MiB -2;17 MiB;12 MiB -3;32 MiB;12  MiB	 -4;48	MiB;16
	      MiB  -5;94  MiB;26 MiB -6;94 MiB;45 MiB -7;186 MiB;83 MiB -8;370
	      MiB;159 MiB -9;674 MiB;311 MiB

       The default preset level in LZMA Utils is -7 while in XZ	 Utils	it  is
       -6, so both use an 8 MiB dictionary by default.

   Streamed vs. non-streamed .lzma files
       The  uncompressed  size	of the file can be stored in the .lzma header.
       LZMA Utils does that when compressing regular files.   The  alternative
       is  to  mark  that  uncompressed size is unknown and use end-of-payload
       marker to indicate where the decompressor should stop.  LZMA Utils uses
       this  method when uncompressed size isn't known, which is the case, for
       example, in pipes.

       xz supports decompressing .lzma files with  or  without	end-of-payload
       marker,	but  all  .lzma	 files	created	 by xz will use end-of-payload
       marker and have uncompressed  size  marked  as  unknown	in  the	 .lzma
       header.	 This may be a problem in some uncommon situations.  For exam‐
       ple, a .lzma decompressor in an embedded device might  work  only  with
       files  that have known uncompressed size.  If you hit this problem, you
       need to use LZMA Utils or LZMA SDK to create .lzma files with known un‐
       compressed size.

   Unsupported .lzma files
       The .lzma format allows lc values up to 8, and lp values up to 4.  LZMA
       Utils can decompress files with any lc and lp, but always creates files
       with  lc=3  and	lp=0.  Creating files with other lc and lp is possible
       with xz and with LZMA SDK.

       The implementation of the LZMA1 filter in liblzma requires that the sum
       of  lc  and lp must not exceed 4.  Thus, .lzma files, which exceed this
       limitation, cannot be decompressed with xz.

       LZMA Utils creates only .lzma files which have a dictionary size of 2^n
       (a power of 2) but accepts files with any dictionary size.  liblzma ac‐
       cepts only .lzma files which have a dictionary size of  2^n  or	2^n  +
       2^(n-1).	  This	is  to	decrease  false positives when detecting .lzma
       files.

       These limitations shouldn't be a problem in practice, since practically
       all  .lzma  files  have been compressed with settings that liblzma will
       accept.

   Trailing garbage
       When decompressing, LZMA Utils silently	ignore	everything  after  the
       first  .lzma  stream.   In  most	 situations, this is a bug.  This also
       means that LZMA Utils don't support  decompressing  concatenated	 .lzma
       files.

       If  there  is  data left after the first .lzma stream, xz considers the
       file to be corrupt unless --single-stream was used.  This may break ob‐
       scure scripts which have assumed that trailing garbage is ignored.

NOTES
   Compressed output may vary
       The  exact  compressed output produced from the same uncompressed input
       file may vary between XZ Utils versions even if compression options are
       identical.  This is because the encoder can be improved (faster or bet‐
       ter compression) without affecting the file  format.   The  output  can
       vary  even  between  different  builds of the same XZ Utils version, if
       different build options are used.

       The above means that once --rsyncable has been implemented, the result‐
       ing  files won't necessarily be rsyncable unless both old and new files
       have been compressed with the same xz version.	This  problem  can  be
       fixed if a part of the encoder implementation is frozen to keep rsynca‐
       ble output stable across xz versions.

   Embedded .xz decompressors
       Embedded .xz decompressor implementations like XZ Embedded don't neces‐
       sarily support files created with integrity check types other than none
       and  crc32.   Since  the	 default  is  --check=crc64,  you   must   use
       --check=none or --check=crc32 when creating files for embedded systems.

       Outside	embedded systems, all .xz format decompressors support all the
       check types, or at least are able to decompress the file without	 veri‐
       fying the integrity check if the particular check is not supported.

       XZ  Embedded supports BCJ filters, but only with the default start off‐
       set.

EXAMPLES
   Basics
       Compress the file foo into foo.xz using the default  compression	 level
       (-6), and remove foo if compression is successful:

	      xz foo

       Decompress  bar.xz  into bar and don't remove bar.xz even if decompres‐
       sion is successful:

	      xz -dk bar.xz

       Create baz.tar.xz with the preset -4e (-4 --extreme), which  is	slower
       than  the  default -6, but needs less memory for compression and decom‐
       pression (48 MiB and 5 MiB, respectively):

	      tar cf - baz | xz -4e > baz.tar.xz

       A mix of compressed and uncompressed files can be decompressed to stan‐
       dard output with a single command:

	      xz -dcf a.txt b.txt.xz c.txt d.txt.lzma > abcd.txt

   Parallel compression of many files
       On  GNU	and *BSD, find(1) and xargs(1) can be used to parallelize com‐
       pression of many files:

	      find . -type f \! -name '*.xz' -print0 \
		  | xargs -0r -P4 -n16 xz -T1

       The -P option to xargs(1) sets the number  of  parallel	xz  processes.
       The best value for the -n option depends on how many files there are to
       be compressed.  If there are only a couple of files, the	 value	should
       probably be 1; with tens of thousands of files, 100 or even more may be
       appropriate to reduce the number of xz  processes  that	xargs(1)  will
       eventually create.

       The option -T1 for xz is there to force it to single-threaded mode, be‐
       cause xargs(1) is used to control the amount of parallelization.

   Robot mode
       Calculate how many bytes have been saved	 in  total  after  compressing
       multiple files:

	      xz --robot --list *.xz | awk '/^totals/{print $5-$4}'

       A  script may want to know that it is using new enough xz.  The follow‐
       ing sh(1) script checks that the version number of the xz  tool	is  at
       least  5.0.0.   This method is compatible with old beta versions, which
       didn't support the --robot option:

	      if ! eval "$(xz --robot --version 2> /dev/null)" ||
		      [ "$XZ_VERSION" -lt 50000002 ]; then
		  echo "Your xz is too old."
	      fi
	      unset XZ_VERSION LIBLZMA_VERSION

       Set a memory usage limit for decompression using XZ_OPT, but if a limit
       has already been set, don't increase it:

	      NEWLIM=$((123 << 20))  # 123 MiB
	      OLDLIM=$(xz --robot --info-memory | cut -f3)
	      if [ $OLDLIM -eq 0 -o $OLDLIM -gt $NEWLIM ]; then
		  XZ_OPT="$XZ_OPT --memlimit-decompress=$NEWLIM"
		  export XZ_OPT
	      fi

   Custom compressor filter chains
       The  simplest  use for custom filter chains is customizing a LZMA2 pre‐
       set.  This can be useful, because the presets cover only	 a  subset  of
       the potentially useful combinations of compression settings.

       The  CompCPU columns of the tables from the descriptions of the options
       -0 ... -9 and --extreme are  useful  when  customizing  LZMA2  presets.
       Here are the relevant parts collected from those two tables:

	      tab(;);  c  c n n.  Preset;CompCPU -0;0 -1;1 -2;2 -3;3 -4;4 -5;5
	      -6;6 -5e;7 -6e;8

       If you know that a file requires somewhat big dictionary (for  example,
       32 MiB)	to  compress well, but you want to compress it quicker than xz
       -8 would do, a preset with a low CompCPU value (for example, 1) can  be
       modified to use a bigger dictionary:

	      xz --lzma2=preset=1,dict=32MiB foo.tar

       With  certain  files,  the above command may be faster than xz -6 while
       compressing significantly better.  However, it must be emphasized  that
       only some files benefit from a big dictionary while keeping the CompCPU
       value low.  The most obvious situation, where a big dictionary can help
       a  lot,	is  an archive containing very similar files of at least a few
       megabytes each.	The dictionary size has	 to  be	 significantly	bigger
       than  any  individual file to allow LZMA2 to take full advantage of the
       similarities between consecutive files.

       If very high compressor and decompressor memory usage is fine, and  the
       file  being compressed is at least several hundred megabytes, it may be
       useful to use an even bigger dictionary than the	 64  MiB  that	xz  -9
       would use:

	      xz -vv --lzma2=dict=192MiB big_foo.tar

       Using -vv (--verbose --verbose) like in the above example can be useful
       to see the memory requirements of the compressor and decompressor.  Re‐
       member that using a dictionary bigger than the size of the uncompressed
       file is waste of memory, so the above command isn't  useful  for	 small
       files.

       Sometimes  the  compression  time  doesn't matter, but the decompressor
       memory usage has to be kept low, for example, to make  it  possible  to
       decompress  the file on an embedded system.  The following command uses
       -6e (-6 --extreme) as a base and sets the dictionary  to	 only  64 KiB.
       The  resulting  file  can  be decompressed with XZ Embedded (that's why
       there is --check=crc32) using about 100 KiB of memory.

	      xz --check=crc32 --lzma2=preset=6e,dict=64KiB foo

       If you want to squeeze out as many bytes	 as  possible,	adjusting  the
       number  of  literal  context bits (lc) and number of position bits (pb)
       can sometimes help.  Adjusting the number of literal position bits (lp)
       might help too, but usually lc and pb are more important.  For example,
       a source code archive contains mostly US-ASCII text, so something  like
       the following might give slightly (like 0.1 %) smaller file than xz -6e
       (try also without lc=4):

	      xz --lzma2=preset=6e,pb=0,lc=4 source_code.tar

       Using another filter together with LZMA2 can improve  compression  with
       certain file types.  For example, to compress a x86-32 or x86-64 shared
       library using the x86 BCJ filter:

	      xz --x86 --lzma2 libfoo.so

       Note that the order of the filter options is significant.  If --x86  is
       specified after --lzma2, xz will give an error, because there cannot be
       any filter after LZMA2, and also because the x86 BCJ filter  cannot  be
       used as the last filter in the chain.

       The  Delta filter together with LZMA2 can give good results with bitmap
       images.	It should usually beat PNG, which has a few more advanced fil‐
       ters than simple delta but uses Deflate for the actual compression.

       The  image  has to be saved in uncompressed format, for example, as un‐
       compressed TIFF.	 The distance parameter of the Delta filter is set  to
       match  the number of bytes per pixel in the image.  For example, 24-bit
       RGB bitmap needs dist=3, and it is also good to pass pb=0 to  LZMA2  to
       accommodate the three-byte alignment:

	      xz --delta=dist=3 --lzma2=pb=0 foo.tiff

       If  multiple  images  have been put into a single archive (for example,
       .tar), the Delta filter will work on that too as	 long  as  all	images
       have the same number of bytes per pixel.

SEE ALSO
       xzdec(1),   xzdiff(1),	xzgrep(1),   xzless(1),	  xzmore(1),  gzip(1),
       bzip2(1), 7z(1)

       XZ Utils: <https://tukaani.org/xz/>
       XZ Embedded: <https://tukaani.org/xz/embedded.html>
       LZMA SDK: <https://7-zip.org/sdk.html>



Tukaani				  2024-12-30				 XZ(1)

XZLESS(1)			   XZ Utils			     XZLESS(1)



NAME
       xzless, lzless - view xz or lzma compressed (text) files

SYNOPSIS
       xzless [file...]
       lzless [file...]

DESCRIPTION
       xzless is a filter that displays text from compressed files to a termi‐
       nal.  Files supported by xz(1) are decompressed; other  files  are  as‐
       sumed  to  be in uncompressed form already.  If no files are given, xz‐
       less reads from standard input.

       xzless uses less(1) to present its output.  Unlike xzmore,  its	choice
       of  pager  cannot  be altered by setting an environment variable.  Com‐
       mands are based on both more(1) and vi(1)  and  allow  back  and	 forth
       movement and searching.	See the less(1) manual for more information.

       The  command  named  lzless is provided for backward compatibility with
       LZMA Utils.

ENVIRONMENT
       LESSMETACHARS
	      A list of characters special to the shell.  Set by xzless unless
	      it is already set in the environment.

       LESSOPEN
	      Set  to a command line to invoke the xz(1) decompressor for pre‐
	      processing the input files to less(1).

SEE ALSO
       less(1), xz(1), xzmore(1), zless(1)



Tukaani				  2024-02-12			     XZLESS(1)

XZMORE(1)			   XZ Utils			     XZMORE(1)



NAME
       xzmore, lzmore - view xz or lzma compressed (text) files

SYNOPSIS
       xzmore [file...]
       lzmore [file...]

DESCRIPTION
       xzmore displays text from compressed files to a terminal using more(1).
       Files supported by xz(1) are decompressed; other files are  assumed  to
       be  in  uncompressed form already.  If no files are given, xzmore reads
       from standard input.  See the more(1) manual for the keyboard commands.

       Note that scrolling backwards might not be possible  depending  on  the
       implementation  of more(1).  This is because xzmore uses a pipe to pass
       the decompressed data to more(1).  xzless(1) uses  less(1)  which  pro‐
       vides more advanced features.

       The  command  lzmore  is	 provided for backward compatibility with LZMA
       Utils.

ENVIRONMENT
       PAGER  If PAGER is set, its value is  used  as  the  pager  instead  of
	      more(1).

SEE ALSO
       more(1), xz(1), xzless(1), zmore(1)



Tukaani				  2024-02-12			     XZMORE(1)

XZGREP(1)			   XZ Utils			     XZGREP(1)



NAME
       xzgrep - search possibly-compressed files for patterns

SYNOPSIS
       xzgrep [option...]  [pattern_list] [file...]
       xzegrep ...
       xzfgrep ...
       lzgrep ...
       lzegrep ...
       lzfgrep ...

DESCRIPTION
       xzgrep  invokes grep(1) on uncompressed contents of files.  The formats
       of the files are determined from the filename suffixes.	Any file  with
       a  suffix  supported  by xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1) will be decompressed; all other files are assumed to  be	uncom‐
       pressed.

       If  no  files  are  specified or file is - then standard input is read.
       When reading from standard input, only files supported by xz(1) are de‐
       compressed.   Other  files  are	assumed to be in uncompressed form al‐
       ready.

       Most options of grep(1) are supported.  However, the following  options
       are not supported:

	   -r, --recursive

	   -R, --dereference-recursive

	   -d, --directories=action

	   -Z, --null

	   -z, --null-data

	   --include=glob

	   --exclude=glob

	   --exclude-from=file

	   --exclude-dir=glob

       xzegrep is an alias for xzgrep -E.  xzfgrep is an alias for xzgrep -F.

       The  commands  lzgrep,  lzegrep,	 and lzfgrep are provided for backward
       compatibility with LZMA Utils.

EXIT STATUS
       0      At least one match was found from at  least  one	of  the	 input
	      files.  No errors occurred.

       1      No  matches  were	 found from any of the input files.  No errors
	      occurred.

       >1     One or more errors occurred.  It	is  unknown  if	 matches  were
	      found.

ENVIRONMENT
       GREP   If GREP is set to a non-empty value, it is used instead of grep,
	      grep -E, or grep -F.

SEE ALSO
       grep(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1), zgrep(1)



Tukaani				  2024-02-13			     XZGREP(1)

XZDIFF(1)			   XZ Utils			     XZDIFF(1)



NAME
       xzcmp, xzdiff, lzcmp, lzdiff - compare compressed files

SYNOPSIS
       xzcmp [option...]  file1 [file2]
       xzdiff ...
       lzcmp ...
       lzdiff ...

DESCRIPTION
       xzcmp  and  xzdiff  compare uncompressed contents of two files.	Uncom‐
       pressed data and options are passed to cmp(1) or diff(1) unless	--help
       or --version is specified.

       If  both	 file1 and file2 are specified, they can be uncompressed files
       or files in formats that xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1)  can decompress.	The required decompression commands are deter‐
       mined from the filename suffixes of file1 and file2.  A	file  with  an
       unknown suffix is assumed to be either uncompressed or in a format that
       xz(1) can decompress.

       If only one filename is provided, file1 must have a suffix  of  a  sup‐
       ported compression format and the name for file2 is assumed to be file1
       with the compression format suffix removed.

       The commands lzcmp and lzdiff are provided for  backward	 compatibility
       with LZMA Utils.

EXIT STATUS
       If  a  decompression error occurs, the exit status is 2.	 Otherwise the
       exit status of cmp(1) or diff(1) is used.

SEE ALSO
       cmp(1), diff(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1)



Tukaani				  2024-02-13			     XZDIFF(1)

XZDIFF(1)			   XZ Utils			     XZDIFF(1)



NAME
       xzcmp, xzdiff, lzcmp, lzdiff - compare compressed files

SYNOPSIS
       xzcmp [option...]  file1 [file2]
       xzdiff ...
       lzcmp ...
       lzdiff ...

DESCRIPTION
       xzcmp  and  xzdiff  compare uncompressed contents of two files.	Uncom‐
       pressed data and options are passed to cmp(1) or diff(1) unless	--help
       or --version is specified.

       If  both	 file1 and file2 are specified, they can be uncompressed files
       or files in formats that xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1)  can decompress.	The required decompression commands are deter‐
       mined from the filename suffixes of file1 and file2.  A	file  with  an
       unknown suffix is assumed to be either uncompressed or in a format that
       xz(1) can decompress.

       If only one filename is provided, file1 must have a suffix  of  a  sup‐
       ported compression format and the name for file2 is assumed to be file1
       with the compression format suffix removed.

       The commands lzcmp and lzdiff are provided for  backward	 compatibility
       with LZMA Utils.

EXIT STATUS
       If  a  decompression error occurs, the exit status is 2.	 Otherwise the
       exit status of cmp(1) or diff(1) is used.

SEE ALSO
       cmp(1), diff(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1)



Tukaani				  2024-02-13			     XZDIFF(1)

XZGREP(1)			   XZ Utils			     XZGREP(1)



NAME
       xzgrep - search possibly-compressed files for patterns

SYNOPSIS
       xzgrep [option...]  [pattern_list] [file...]
       xzegrep ...
       xzfgrep ...
       lzgrep ...
       lzegrep ...
       lzfgrep ...

DESCRIPTION
       xzgrep  invokes grep(1) on uncompressed contents of files.  The formats
       of the files are determined from the filename suffixes.	Any file  with
       a  suffix  supported  by xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1) will be decompressed; all other files are assumed to  be	uncom‐
       pressed.

       If  no  files  are  specified or file is - then standard input is read.
       When reading from standard input, only files supported by xz(1) are de‐
       compressed.   Other  files  are	assumed to be in uncompressed form al‐
       ready.

       Most options of grep(1) are supported.  However, the following  options
       are not supported:

	   -r, --recursive

	   -R, --dereference-recursive

	   -d, --directories=action

	   -Z, --null

	   -z, --null-data

	   --include=glob

	   --exclude=glob

	   --exclude-from=file

	   --exclude-dir=glob

       xzegrep is an alias for xzgrep -E.  xzfgrep is an alias for xzgrep -F.

       The  commands  lzgrep,  lzegrep,	 and lzfgrep are provided for backward
       compatibility with LZMA Utils.

EXIT STATUS
       0      At least one match was found from at  least  one	of  the	 input
	      files.  No errors occurred.

       1      No  matches  were	 found from any of the input files.  No errors
	      occurred.

       >1     One or more errors occurred.  It	is  unknown  if	 matches  were
	      found.

ENVIRONMENT
       GREP   If GREP is set to a non-empty value, it is used instead of grep,
	      grep -E, or grep -F.

SEE ALSO
       grep(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1), zgrep(1)



Tukaani				  2024-02-13			     XZGREP(1)

XZGREP(1)			   XZ Utils			     XZGREP(1)



NAME
       xzgrep - search possibly-compressed files for patterns

SYNOPSIS
       xzgrep [option...]  [pattern_list] [file...]
       xzegrep ...
       xzfgrep ...
       lzgrep ...
       lzegrep ...
       lzfgrep ...

DESCRIPTION
       xzgrep  invokes grep(1) on uncompressed contents of files.  The formats
       of the files are determined from the filename suffixes.	Any file  with
       a  suffix  supported  by xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1) will be decompressed; all other files are assumed to  be	uncom‐
       pressed.

       If  no  files  are  specified or file is - then standard input is read.
       When reading from standard input, only files supported by xz(1) are de‐
       compressed.   Other  files  are	assumed to be in uncompressed form al‐
       ready.

       Most options of grep(1) are supported.  However, the following  options
       are not supported:

	   -r, --recursive

	   -R, --dereference-recursive

	   -d, --directories=action

	   -Z, --null

	   -z, --null-data

	   --include=glob

	   --exclude=glob

	   --exclude-from=file

	   --exclude-dir=glob

       xzegrep is an alias for xzgrep -E.  xzfgrep is an alias for xzgrep -F.

       The  commands  lzgrep,  lzegrep,	 and lzfgrep are provided for backward
       compatibility with LZMA Utils.

EXIT STATUS
       0      At least one match was found from at  least  one	of  the	 input
	      files.  No errors occurred.

       1      No  matches  were	 found from any of the input files.  No errors
	      occurred.

       >1     One or more errors occurred.  It	is  unknown  if	 matches  were
	      found.

ENVIRONMENT
       GREP   If GREP is set to a non-empty value, it is used instead of grep,
	      grep -E, or grep -F.

SEE ALSO
       grep(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1), zgrep(1)



Tukaani				  2024-02-13			     XZGREP(1)

XZGREP(1)			   XZ Utils			     XZGREP(1)



NAME
       xzgrep - search possibly-compressed files for patterns

SYNOPSIS
       xzgrep [option...]  [pattern_list] [file...]
       xzegrep ...
       xzfgrep ...
       lzgrep ...
       lzegrep ...
       lzfgrep ...

DESCRIPTION
       xzgrep  invokes grep(1) on uncompressed contents of files.  The formats
       of the files are determined from the filename suffixes.	Any file  with
       a  suffix  supported  by xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1) will be decompressed; all other files are assumed to  be	uncom‐
       pressed.

       If  no  files  are  specified or file is - then standard input is read.
       When reading from standard input, only files supported by xz(1) are de‐
       compressed.   Other  files  are	assumed to be in uncompressed form al‐
       ready.

       Most options of grep(1) are supported.  However, the following  options
       are not supported:

	   -r, --recursive

	   -R, --dereference-recursive

	   -d, --directories=action

	   -Z, --null

	   -z, --null-data

	   --include=glob

	   --exclude=glob

	   --exclude-from=file

	   --exclude-dir=glob

       xzegrep is an alias for xzgrep -E.  xzfgrep is an alias for xzgrep -F.

       The  commands  lzgrep,  lzegrep,	 and lzfgrep are provided for backward
       compatibility with LZMA Utils.

EXIT STATUS
       0      At least one match was found from at  least  one	of  the	 input
	      files.  No errors occurred.

       1      No  matches  were	 found from any of the input files.  No errors
	      occurred.

       >1     One or more errors occurred.  It	is  unknown  if	 matches  were
	      found.

ENVIRONMENT
       GREP   If GREP is set to a non-empty value, it is used instead of grep,
	      grep -E, or grep -F.

SEE ALSO
       grep(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1), zgrep(1)



Tukaani				  2024-02-13			     XZGREP(1)

XZGREP(1)			   XZ Utils			     XZGREP(1)



NAME
       xzgrep - search possibly-compressed files for patterns

SYNOPSIS
       xzgrep [option...]  [pattern_list] [file...]
       xzegrep ...
       xzfgrep ...
       lzgrep ...
       lzegrep ...
       lzfgrep ...

DESCRIPTION
       xzgrep  invokes grep(1) on uncompressed contents of files.  The formats
       of the files are determined from the filename suffixes.	Any file  with
       a  suffix  supported  by xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1) will be decompressed; all other files are assumed to  be	uncom‐
       pressed.

       If  no  files  are  specified or file is - then standard input is read.
       When reading from standard input, only files supported by xz(1) are de‐
       compressed.   Other  files  are	assumed to be in uncompressed form al‐
       ready.

       Most options of grep(1) are supported.  However, the following  options
       are not supported:

	   -r, --recursive

	   -R, --dereference-recursive

	   -d, --directories=action

	   -Z, --null

	   -z, --null-data

	   --include=glob

	   --exclude=glob

	   --exclude-from=file

	   --exclude-dir=glob

       xzegrep is an alias for xzgrep -E.  xzfgrep is an alias for xzgrep -F.

       The  commands  lzgrep,  lzegrep,	 and lzfgrep are provided for backward
       compatibility with LZMA Utils.

EXIT STATUS
       0      At least one match was found from at  least  one	of  the	 input
	      files.  No errors occurred.

       1      No  matches  were	 found from any of the input files.  No errors
	      occurred.

       >1     One or more errors occurred.  It	is  unknown  if	 matches  were
	      found.

ENVIRONMENT
       GREP   If GREP is set to a non-empty value, it is used instead of grep,
	      grep -E, or grep -F.

SEE ALSO
       grep(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1), zgrep(1)



Tukaani				  2024-02-13			     XZGREP(1)

XZGREP(1)			   XZ Utils			     XZGREP(1)



NAME
       xzgrep - search possibly-compressed files for patterns

SYNOPSIS
       xzgrep [option...]  [pattern_list] [file...]
       xzegrep ...
       xzfgrep ...
       lzgrep ...
       lzegrep ...
       lzfgrep ...

DESCRIPTION
       xzgrep  invokes grep(1) on uncompressed contents of files.  The formats
       of the files are determined from the filename suffixes.	Any file  with
       a  suffix  supported  by xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), or
       lz4(1) will be decompressed; all other files are assumed to  be	uncom‐
       pressed.

       If  no  files  are  specified or file is - then standard input is read.
       When reading from standard input, only files supported by xz(1) are de‐
       compressed.   Other  files  are	assumed to be in uncompressed form al‐
       ready.

       Most options of grep(1) are supported.  However, the following  options
       are not supported:

	   -r, --recursive

	   -R, --dereference-recursive

	   -d, --directories=action

	   -Z, --null

	   -z, --null-data

	   --include=glob

	   --exclude=glob

	   --exclude-from=file

	   --exclude-dir=glob

       xzegrep is an alias for xzgrep -E.  xzfgrep is an alias for xzgrep -F.

       The  commands  lzgrep,  lzegrep,	 and lzfgrep are provided for backward
       compatibility with LZMA Utils.

EXIT STATUS
       0      At least one match was found from at  least  one	of  the	 input
	      files.  No errors occurred.

       1      No  matches  were	 found from any of the input files.  No errors
	      occurred.

       >1     One or more errors occurred.  It	is  unknown  if	 matches  were
	      found.

ENVIRONMENT
       GREP   If GREP is set to a non-empty value, it is used instead of grep,
	      grep -E, or grep -F.

SEE ALSO
       grep(1), xz(1), gzip(1), bzip2(1), lzop(1), zstd(1), lz4(1), zgrep(1)



Tukaani				  2024-02-13			     XZGREP(1)

XZLESS(1)			   XZ Utils			     XZLESS(1)



NAME
       xzless, lzless - view xz or lzma compressed (text) files

SYNOPSIS
       xzless [file...]
       lzless [file...]

DESCRIPTION
       xzless is a filter that displays text from compressed files to a termi‐
       nal.  Files supported by xz(1) are decompressed; other  files  are  as‐
       sumed  to  be in uncompressed form already.  If no files are given, xz‐
       less reads from standard input.

       xzless uses less(1) to present its output.  Unlike xzmore,  its	choice
       of  pager  cannot  be altered by setting an environment variable.  Com‐
       mands are based on both more(1) and vi(1)  and  allow  back  and	 forth
       movement and searching.	See the less(1) manual for more information.

       The  command  named  lzless is provided for backward compatibility with
       LZMA Utils.

ENVIRONMENT
       LESSMETACHARS
	      A list of characters special to the shell.  Set by xzless unless
	      it is already set in the environment.

       LESSOPEN
	      Set  to a command line to invoke the xz(1) decompressor for pre‐
	      processing the input files to less(1).

SEE ALSO
       less(1), xz(1), xzmore(1), zless(1)



Tukaani				  2024-02-12			     XZLESS(1)

XZ(1)				   XZ Utils				 XZ(1)



NAME
       xz,  unxz,  xzcat, lzma, unlzma, lzcat - Compress or decompress .xz and
       .lzma files

SYNOPSIS
       xz [option...]  [file...]

COMMAND ALIASES
       unxz is equivalent to xz --decompress.
       xzcat is equivalent to xz --decompress --stdout.
       lzma is equivalent to xz --format=lzma.
       unlzma is equivalent to xz --format=lzma --decompress.
       lzcat is equivalent to xz --format=lzma --decompress --stdout.

       When writing scripts that need to decompress files, it  is  recommended
       to  always use the name xz with appropriate arguments (xz -d or xz -dc)
       instead of the names unxz and xzcat.

DESCRIPTION
       xz is a general-purpose data compression tool with command line	syntax
       similar	to  gzip(1)  and  bzip2(1).  The native file format is the .xz
       format, but the legacy .lzma format used by LZMA	 Utils	and  raw  com‐
       pressed	streams	 with  no container format headers are also supported.
       In addition, decompression of the .lz format used by lzip is supported.

       xz compresses or decompresses each file according to the selected oper‐
       ation mode.  If no files are given or file is -, xz reads from standard
       input and writes the processed data to standard output.	xz will refuse
       (display	 an error and skip the file) to write compressed data to stan‐
       dard output if it is a terminal.	 Similarly, xz	will  refuse  to  read
       compressed data from standard input if it is a terminal.

       Unless  --stdout	 is specified, files other than - are written to a new
       file whose name is derived from the source file name:

       •  When compressing, the suffix of  the	target	file  format  (.xz  or
	  .lzma)  is  appended	to the source filename to get the target file‐
	  name.

       •  When decompressing, the .xz, .lzma, or .lz suffix  is	 removed  from
	  the  filename	 to  get  the target filename.	xz also recognizes the
	  suffixes .txz and .tlz, and replaces them with the .tar suffix.

       If the target file already exists, an error is displayed and  the  file
       is skipped.

       Unless  writing	to standard output, xz will display a warning and skip
       the file if any of the following applies:

       •  File is not a regular file.  Symbolic links are  not	followed,  and
	  thus they are not considered to be regular files.

       •  File has more than one hard link.

       •  File has setuid, setgid, or sticky bit set.

       •  The  operation  mode	is  set to compress and the file already has a
	  suffix of the target file format (.xz or .txz	 when  compressing  to
	  the .xz format, and .lzma or .tlz when compressing to the .lzma for‐
	  mat).

       •  The operation mode is set to decompress and the file doesn't have  a
	  suffix of any of the supported file formats (.xz, .txz, .lzma, .tlz,
	  or .lz).

       After successfully compressing or decompressing the file, xz copies the
       owner,  group, permissions, access time, and modification time from the
       source file to the target file.	If copying the group fails,  the  per‐
       missions are modified so that the target file doesn't become accessible
       to users who didn't have permission to  access  the  source  file.   xz
       doesn't support copying other metadata like access control lists or ex‐
       tended attributes yet.

       Once the target file has been successfully closed, the source  file  is
       removed	unless --keep was specified.  The source file is never removed
       if the output is written to standard output or if an error occurs.

       Sending SIGINFO or SIGUSR1 to the xz process makes  it  print  progress
       information  to	standard  error.  This has only limited use since when
       standard error is a terminal, using --verbose will display an automati‐
       cally updating progress indicator.

   Memory usage
       The  memory  usage of xz varies from a few hundred kilobytes to several
       gigabytes depending on the compression  settings.   The	settings  used
       when compressing a file determine the memory requirements of the decom‐
       pressor.	 Typically the decompressor needs 5 % to 20 % of the amount of
       memory that the compressor needed when creating the file.  For example,
       decompressing a file created with xz -9 currently  requires  65 MiB  of
       memory.	 Still,	 it is possible to have .xz files that require several
       gigabytes of memory to decompress.

       Especially users of older systems may  find  the	 possibility  of  very
       large  memory  usage  annoying.	To prevent uncomfortable surprises, xz
       has a built-in memory usage limiter,  which  is	disabled  by  default.
       While  some operating systems provide ways to limit the memory usage of
       processes, relying on it wasn't deemed to be flexible enough (for exam‐
       ple, using ulimit(1) to limit virtual memory tends to cripple mmap(2)).

       The  memory  usage  limiter can be enabled with the command line option
       --memlimit=limit.  Often it is more convenient to enable the limiter by
       default	by  setting the environment variable XZ_DEFAULTS, for example,
       XZ_DEFAULTS=--memlimit=150MiB.  It is possible to set the limits	 sepa‐
       rately  for  compression	 and  decompression  by	 using --memlimit-com‐
       press=limit and --memlimit-decompress=limit.  Using these  two  options
       outside	XZ_DEFAULTS is rarely useful because a single run of xz cannot
       do both compression  and	 decompression	and  --memlimit=limit  (or  -M
       limit) is shorter to type on the command line.

       If  the specified memory usage limit is exceeded when decompressing, xz
       will display an error and decompressing the file	 will  fail.   If  the
       limit  is  exceeded when compressing, xz will try to scale the settings
       down so that the limit is no longer exceeded (except when using	--for‐
       mat=raw	or --no-adjust).  This way the operation won't fail unless the
       limit is very small.  The scaling of the settings is done in steps that
       don't match the compression level presets, for example, if the limit is
       only slightly less than the amount required for	xz  -9,	 the  settings
       will be scaled down only a little, not all the way down to xz -8.

   Concatenation and padding with .xz files
       It is possible to concatenate .xz files as is.  xz will decompress such
       files as if they were a single .xz file.

       It is possible to insert padding between the concatenated parts or  af‐
       ter the last part.  The padding must consist of null bytes and the size
       of the padding must be a multiple of four bytes.	 This can  be  useful,
       for  example,  if the .xz file is stored on a medium that measures file
       sizes in 512-byte blocks.

       Concatenation and padding are not  allowed  with	 .lzma	files  or  raw
       streams.

OPTIONS
   Integer suffixes and special values
       In  most places where an integer argument is expected, an optional suf‐
       fix is supported to easily indicate large integers.  There must	be  no
       space between the integer and the suffix.

       KiB    Multiply	the integer by 1,024 (2^10).  Ki, k, kB, K, and KB are
	      accepted as synonyms for KiB.

       MiB    Multiply the integer by 1,048,576 (2^20).	 Mi, m, M, and MB  are
	      accepted as synonyms for MiB.

       GiB    Multiply	the integer by 1,073,741,824 (2^30).  Gi, g, G, and GB
	      are accepted as synonyms for GiB.

       The special value max can be used to indicate the maximum integer value
       supported by the option.

   Operation mode
       If  multiple  operation	mode options are given, the last one takes ef‐
       fect.

       -z, --compress
	      Compress.	 This is the default operation mode when no  operation
	      mode  option is specified and no other operation mode is implied
	      from the command name (for example, unxz implies --decompress).

	      After successful compression, the source file is removed	unless
	      writing to standard output or --keep was specified.

       -d, --decompress, --uncompress
	      Decompress.   After successful decompression, the source file is
	      removed unless writing to standard output or --keep  was	speci‐
	      fied.

       -t, --test
	      Test  the integrity of compressed files.	This option is equiva‐
	      lent to --decompress --stdout except that the decompressed  data
	      is  discarded  instead  of being written to standard output.  No
	      files are created or removed.

       -l, --list
	      Print information about compressed files.	 No uncompressed  out‐
	      put  is  produced, and no files are created or removed.  In list
	      mode, the program cannot read the compressed data from  standard
	      input or from other unseekable sources.

	      The  default  listing  shows  basic information about files, one
	      file per line.  To get more detailed information, use  also  the
	      --verbose	 option.   For	even  more  information, use --verbose
	      twice, but note that this may be slow, because getting  all  the
	      extra  information  requires  many  seeks.  The width of verbose
	      output exceeds 80 characters, so piping the output to, for exam‐
	      ple,  less -S  may  be  convenient  if  the  terminal isn't wide
	      enough.

	      The exact output may vary between xz versions and different  lo‐
	      cales.   For  machine-readable  output, --robot --list should be
	      used.

   Operation modifiers
       -k, --keep
	      Don't delete the input files.

	      Since xz 5.2.6, this option also makes xz compress or decompress
	      even if the input is a symbolic link to a regular file, has more
	      than one hard link, or has the setuid,  setgid,  or  sticky  bit
	      set.   The setuid, setgid, and sticky bits are not copied to the
	      target file.  In	earlier	 versions  this	 was  only  done  with
	      --force.

       -f, --force
	      This option has several effects:

	      •	 If the target file already exists, delete it before compress‐
		 ing or decompressing.

	      •	 Compress or decompress even if the input is a	symbolic  link
		 to  a	regular	 file, has more than one hard link, or has the
		 setuid, setgid, or sticky bit set.  The setuid,  setgid,  and
		 sticky bits are not copied to the target file.

	      •	 When  used with --decompress --stdout and xz cannot recognize
		 the type of the source file, copy the source file  as	is  to
		 standard  output.   This allows xzcat --force to be used like
		 cat(1) for files that have not been compressed with xz.  Note
		 that in future, xz might support new compressed file formats,
		 which may make xz decompress more types of files  instead  of
		 copying  them	as is to standard output.  --format=format can
		 be used to restrict xz to decompress only a single file  for‐
		 mat.

       -c, --stdout, --to-stdout
	      Write the compressed or decompressed data to standard output in‐
	      stead of a file.	This implies --keep.

       --single-stream
	      Decompress only the first .xz stream, and silently ignore possi‐
	      ble  remaining  input  data following the stream.	 Normally such
	      trailing garbage makes xz display an error.

	      xz never decompresses more than one stream from .lzma  files  or
	      raw  streams, but this option still makes xz ignore the possible
	      trailing data after the .lzma file or raw stream.

	      This option has no effect if the operation mode is not  --decom‐
	      press or --test.

       --no-sparse
	      Disable  creation of sparse files.  By default, if decompressing
	      into a regular file, xz tries to make the file sparse if the de‐
	      compressed  data	contains  long	sequences of binary zeros.  It
	      also works when writing to standard output as long  as  standard
	      output  is  connected  to	 a regular file and certain additional
	      conditions are met to make it safe.  Creating sparse  files  may
	      save  disk  space and speed up the decompression by reducing the
	      amount of disk I/O.

       -S .suf, --suffix=.suf
	      When compressing, use .suf as the suffix for the target file in‐
	      stead  of	 .xz  or .lzma.	 If not writing to standard output and
	      the source file already has the suffix .suf, a warning  is  dis‐
	      played and the file is skipped.

	      When  decompressing, recognize files with the suffix .suf in ad‐
	      dition to files with the .xz, .txz, .lzma, .tlz, or .lz  suffix.
	      If the source file has the suffix .suf, the suffix is removed to
	      get the target filename.

	      When compressing or decompressing	 raw  streams  (--format=raw),
	      the  suffix  must always be specified unless writing to standard
	      output, because there is no default suffix for raw streams.

       --files[=file]
	      Read the filenames to process from file;	if  file  is  omitted,
	      filenames	 are read from standard input.	Filenames must be ter‐
	      minated with the newline character.  A dash (-) is  taken	 as  a
	      regular  filename; it doesn't mean standard input.  If filenames
	      are given also as command line arguments, they are processed be‐
	      fore the filenames read from file.

       --files0[=file]
	      This  is	identical  to --files[=file] except that each filename
	      must be terminated with the null character.

   Basic file format and compression options
       -F format, --format=format
	      Specify the file format to compress or decompress:

	      auto   This is the default.  When compressing, auto  is  equiva‐
		     lent  to xz.  When decompressing, the format of the input
		     file is automatically detected.  Note  that  raw  streams
		     (created with --format=raw) cannot be auto-detected.

	      xz     Compress to the .xz file format, or accept only .xz files
		     when decompressing.

	      lzma, alone
		     Compress to the legacy .lzma file format, or accept  only
		     .lzma  files  when	 decompressing.	  The alternative name
		     alone is provided for backwards compatibility  with  LZMA
		     Utils.

	      lzip   Accept only .lz files when decompressing.	Compression is
		     not supported.

		     The .lz format version 0 and the unextended version 1 are
		     supported.	 Version 0 files were produced by lzip 1.3 and
		     older.  Such files aren't common but may  be  found  from
		     file  archives  as a few source packages were released in
		     this format.  People might have  old  personal  files  in
		     this  format  too.	  Decompression support for the format
		     version 0 was removed in lzip 1.18.

		     lzip 1.4 and later create files in the format version  1.
		     The  sync	flush marker extension to the format version 1
		     was added in lzip 1.6.  This extension is rarely used and
		     isn't supported by xz (diagnosed as corrupt input).

	      raw    Compress  or  uncompress a raw stream (no headers).  This
		     is meant for advanced users only.	To decode raw streams,
		     you need use --format=raw and explicitly specify the fil‐
		     ter chain, which normally would have been stored  in  the
		     container headers.

       -C check, --check=check
	      Specify  the  type  of the integrity check.  The check is calcu‐
	      lated from the uncompressed data and stored  in  the  .xz	 file.
	      This  option  has	 an  effect only when compressing into the .xz
	      format; the .lzma format doesn't support integrity checks.   The
	      integrity check (if any) is verified when the .xz file is decom‐
	      pressed.

	      Supported check types:

	      none   Don't calculate an integrity check at all.	 This is  usu‐
		     ally  a  bad  idea.  This can be useful when integrity of
		     the data is verified by other means anyway.

	      crc32  Calculate CRC32  using  the  polynomial  from  IEEE-802.3
		     (Ethernet).

	      crc64  Calculate CRC64 using the polynomial from ECMA-182.  This
		     is the default, since it is slightly better than CRC32 at
		     detecting	damaged files and the speed difference is neg‐
		     ligible.

	      sha256 Calculate SHA-256.	 This is somewhat  slower  than	 CRC32
		     and CRC64.

	      Integrity	 of the .xz headers is always verified with CRC32.  It
	      is not possible to change or disable it.

       --ignore-check
	      Don't verify the integrity check of the compressed data when de‐
	      compressing.   The CRC32 values in the .xz headers will still be
	      verified normally.

	      Do not use this option unless you know what you are doing.  Pos‐
	      sible reasons to use this option:

	      •	 Trying to recover data from a corrupt .xz file.

	      •	 Speeding  up decompression.  This matters mostly with SHA-256
		 or with files that have compressed extremely well.  It's rec‐
		 ommended  to  not use this option for this purpose unless the
		 file integrity is verified externally in some other way.

       -0 ... -9
	      Select a compression preset level.  The default is -6.  If  mul‐
	      tiple  preset  levels  are specified, the last one takes effect.
	      If a custom filter chain was already specified, setting  a  com‐
	      pression preset level clears the custom filter chain.

	      The  differences	between	 the presets are more significant than
	      with gzip(1) and bzip2(1).  The  selected	 compression  settings
	      determine	 the memory requirements of the decompressor, thus us‐
	      ing a too high preset level might make it painful to  decompress
	      the  file	 on an old system with little RAM.  Specifically, it's
	      not a good idea to blindly use -9 for everything like  it	 often
	      is with gzip(1) and bzip2(1).

	      -0 ... -3
		     These  are somewhat fast presets.	-0 is sometimes faster
		     than gzip -9 while compressing much better.   The	higher
		     ones  often have speed comparable to bzip2(1) with compa‐
		     rable or better compression ratio, although  the  results
		     depend a lot on the type of data being compressed.

	      -4 ... -6
		     Good  to very good compression while keeping decompressor
		     memory usage reasonable even for old systems.  -6 is  the
		     default,  which is usually a good choice for distributing
		     files that need to be decompressible even on systems with
		     only  16 MiB  RAM.	  (-5e or -6e may be worth considering
		     too.  See --extreme.)

	      -7 ... -9
		     These are like -6 but with higher compressor  and	decom‐
		     pressor  memory requirements.  These are useful only when
		     compressing files bigger than 8 MiB, 16 MiB, and  32 MiB,
		     respectively.

	      On the same hardware, the decompression speed is approximately a
	      constant number of bytes of  compressed  data  per  second.   In
	      other  words,  the better the compression, the faster the decom‐
	      pression will usually be.	 This also means that  the  amount  of
	      uncompressed output produced per second can vary a lot.

	      The following table summarises the features of the presets:

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem -0;256 KiB;0;3 MiB;1 MiB -1;1 MiB;1;9
		     MiB;2 MiB -2;2 MiB;2;17 MiB;3 MiB -3;4 MiB;3;32 MiB;5 MiB
		     -4;4 MiB;4;48 MiB;5 MiB  -5;8  MiB;5;94  MiB;9  MiB  -6;8
		     MiB;6;94  MiB;9  MiB  -7;16  MiB;6;186  MiB;17  MiB -8;32
		     MiB;6;370 MiB;33 MiB -9;64 MiB;6;674 MiB;65 MiB

	      Column descriptions:

	      •	 DictSize is the LZMA2 dictionary size.	 It is waste of memory
		 to  use a dictionary bigger than the size of the uncompressed
		 file.	This is why it is good to avoid using the  presets  -7
		 ...  -9 when there's no real need for them.  At -6 and lower,
		 the amount of memory wasted is usually low enough to not mat‐
		 ter.

	      •	 CompCPU  is a simplified representation of the LZMA2 settings
		 that affect compression speed.	 The dictionary	 size  affects
		 speed too, so while CompCPU is the same for levels -6 ... -9,
		 higher levels still tend to be a little slower.  To get  even
		 slower and thus possibly better compression, see --extreme.

	      •	 CompMem  contains  the	 compressor memory requirements in the
		 single-threaded mode.	It may vary slightly between  xz  ver‐
		 sions.

	      •	 DecMem	 contains  the decompressor memory requirements.  That
		 is, the compression settings determine	 the  memory  require‐
		 ments of the decompressor.  The exact decompressor memory us‐
		 age is slightly more than the LZMA2 dictionary size, but  the
		 values	 in  the  table	 have been rounded up to the next full
		 MiB.

	      Memory requirements of the multi-threaded mode are significantly
	      higher  than that of the single-threaded mode.  With the default
	      value of --block-size, each thread needs 3*3*DictSize plus Comp‐
	      Mem  or  DecMem.	For example, four threads with preset -6 needs
	      660–670 MiB of memory.

       -e, --extreme
	      Use a slower variant of the selected  compression	 preset	 level
	      (-0 ... -9) to hopefully get a little bit better compression ra‐
	      tio, but with bad luck this can also make it worse.   Decompres‐
	      sor  memory  usage  is not affected, but compressor memory usage
	      increases a little at preset levels -0 ... -3.

	      Since there are two presets  with	 dictionary  sizes  4 MiB  and
	      8 MiB,  the  presets  -3e	 and  -5e use slightly faster settings
	      (lower CompCPU) than -4e and -6e, respectively.  That way no two
	      presets are identical.

		     tab(;);  c	 c  c  c  c  n	n n n n.  Preset;DictSize;Com‐
		     pCPU;CompMem;DecMem  -0e;256  KiB;8;4  MiB;1  MiB	 -1e;1
		     MiB;8;13	MiB;2  MiB  -2e;2  MiB;8;25  MiB;3  MiB	 -3e;4
		     MiB;7;48  MiB;5  MiB  -4e;4  MiB;8;48  MiB;5  MiB	 -5e;8
		     MiB;7;94  MiB;9  MiB  -6e;8  MiB;8;94  MiB;9  MiB	-7e;16
		     MiB;8;186 MiB;17 MiB -8e;32 MiB;8;370 MiB;33  MiB	-9e;64
		     MiB;8;674 MiB;65 MiB

	      For  example,  there  are a total of four presets that use 8 MiB
	      dictionary, whose order from the fastest to the slowest  is  -5,
	      -6, -5e, and -6e.

       --fast
       --best These  are  somewhat  misleading	aliases for -0 and -9, respec‐
	      tively.  These are provided  only	 for  backwards	 compatibility
	      with LZMA Utils.	Avoid using these options.

       --block-size=size
	      When  compressing	 to  the .xz format, split the input data into
	      blocks of size bytes.  The blocks are  compressed	 independently
	      from each other, which helps with multi-threading and makes lim‐
	      ited random-access decompression possible.  This option is typi‐
	      cally  used to override the default block size in multi-threaded
	      mode, but this option can be used in single-threaded mode too.

	      In multi-threaded mode about three times size bytes will be  al‐
	      located  in each thread for buffering input and output.  The de‐
	      fault size is three times the LZMA2 dictionary size  or  1  MiB,
	      whichever is more.  Typically a good value is 2–4 times the size
	      of the LZMA2 dictionary or at least 1 MiB.  Using size less than
	      the LZMA2 dictionary size is waste of RAM because then the LZMA2
	      dictionary buffer will never get fully used.  In	multi-threaded
	      mode,  the  sizes of the blocks are stored in the block headers.
	      This size information is required for multi-threaded  decompres‐
	      sion.

	      In  single-threaded  mode no block splitting is done by default.
	      Setting this option doesn't affect memory usage.	No size infor‐
	      mation is stored in block headers, thus files created in single-
	      threaded mode won't be identical	to  files  created  in	multi-
	      threaded	mode.  The lack of size information also means that xz
	      won't be able decompress the files in multi-threaded mode.

       --block-list=items
	      When compressing to the .xz format, start a new  block  with  an
	      optional custom filter chain after the given intervals of uncom‐
	      pressed data.

	      The items are a comma-separated list.  Each item consists of  an
	      optional filter chain number between 0 and 9 followed by a colon
	      (:) and a required size of uncompressed data.  Omitting an  item
	      (two  or more consecutive commas) is a shorthand to use the size
	      and filters of the previous item.

	      If the input file is bigger than the sum of the sizes in	items,
	      the  last item is repeated until the end of the file.  A special
	      value of 0 may be used as the last size  to  indicate  that  the
	      rest of the file should be encoded as a single block.

	      An  alternative  filter chain for each block can be specified in
	      combination with the --filters1=filters  ...  --filters9=filters
	      options.	 These options define filter chains with an identifier
	      between 1–9.  Filter chain 0 can be used to refer to the default
	      filter  chain,  which  is	 the  same  as not specifying a filter
	      chain.  The filter chain identifier can be used before  the  un‐
	      compressed  size,	 followed by a colon (:).  For example, if one
	      specifies	 --block-list=1:2MiB,3:2MiB,2:4MiB,,2MiB,0:4MiB	  then
	      blocks will be created using:

	      •	 The filter chain specified by --filters1 and 2 MiB input

	      •	 The filter chain specified by --filters3 and 2 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The filter chain specified by --filters2 and 4 MiB input

	      •	 The default filter chain and 2 MiB input

	      •	 The  default filter chain and 4 MiB input for every block un‐
		 til end of input.

	      If one specifies a size that exceeds the	encoder's  block  size
	      (either  the  default value in threaded mode or the value speci‐
	      fied with --block-size=size), the encoder will create additional
	      blocks while keeping the boundaries specified in items.  For ex‐
	      ample,	  if	  one	    specifies	    --block-size=10MiB
	      --block-list=5MiB,10MiB,8MiB,12MiB,24MiB	and  the input file is
	      80 MiB, one will get 11 blocks: 5, 10, 8, 10, 2, 10, 10, 4,  10,
	      10, and 1 MiB.

	      In multi-threaded mode the sizes of the blocks are stored in the
	      block headers.  This isn't done in single-threaded mode, so  the
	      encoded  output won't be identical to that of the multi-threaded
	      mode.

       --flush-timeout=timeout
	      When compressing, if more than timeout milliseconds (a  positive
	      integer)	has  passed  since the previous flush and reading more
	      input would block, all the pending input data  is	 flushed  from
	      the  encoder  and made available in the output stream.  This can
	      be useful if xz is used to compress data that is streamed over a
	      network.	 Small	timeout	 values make the data available at the
	      receiving end with a small delay, but large timeout values  give
	      better compression ratio.

	      This  feature  is disabled by default.  If this option is speci‐
	      fied more than once, the last one	 takes	effect.	  The  special
	      timeout  value  of 0 can be used to explicitly disable this fea‐
	      ture.

	      This feature is not available on non-POSIX systems.

	      This feature is still experimental.  Currently xz is  unsuitable
	      for  decompressing  the  stream  in real time due to how xz does
	      buffering.

       --memlimit-compress=limit
	      Set a memory usage limit for compression.	  If  this  option  is
	      specified multiple times, the last one takes effect.

	      If the compression settings exceed the limit, xz will attempt to
	      adjust the settings downwards so that the limit is no longer ex‐
	      ceeded  and display a notice that automatic adjustment was done.
	      The adjustments are done in this order: reducing the  number  of
	      threads, switching to single-threaded mode if even one thread in
	      multi-threaded mode exceeds the limit, and finally reducing  the
	      LZMA2 dictionary size.

	      When  compressing	 with  --format=raw or if --no-adjust has been
	      specified, only the number of threads may be  reduced  since  it
	      can be done without affecting the compressed output.

	      If  the  limit cannot be met even with the adjustments described
	      above, an error is displayed and xz will exit with  exit	status
	      1.

	      The limit can be specified in multiple ways:

	      •	 The  limit can be an absolute value in bytes.	Using an inte‐
		 ger suffix like MiB can be useful.  Example:  --memlimit-com‐
		 press=80MiB

	      •	 The  limit can be specified as a percentage of total physical
		 memory (RAM).	This can be useful especially when setting the
		 XZ_DEFAULTS  environment  variable  in a shell initialization
		 script that is shared between different computers.  That  way
		 the  limit  is automatically bigger on systems with more mem‐
		 ory.  Example: --memlimit-compress=70%

	      •	 The limit can be reset back to its default value  by  setting
		 it  to	 0.  This is currently equivalent to setting the limit
		 to max (no memory usage limit).

	      For 32-bit xz there is a special case: if	 the  limit  would  be
	      over 4020 MiB, the limit is set to 4020 MiB.  On MIPS32 2000 MiB
	      is used instead.	(The values 0 and max aren't affected by this.
	      A similar feature doesn't exist for decompression.)  This can be
	      helpful when a 32-bit executable has  access  to	4 GiB  address
	      space  (2	 GiB on MIPS32) while hopefully doing no harm in other
	      situations.

	      See also the section Memory usage.

       --memlimit-decompress=limit
	      Set a memory usage limit for decompression.  This	 also  affects
	      the  --list  mode.  If the operation is not possible without ex‐
	      ceeding the limit, xz will display an  error  and	 decompressing
	      the  file will fail.  See --memlimit-compress=limit for possible
	      ways to specify the limit.

       --memlimit-mt-decompress=limit
	      Set a memory usage limit for multi-threaded decompression.  This
	      can  only	 affect the number of threads; this will never make xz
	      refuse to decompress a file.  If limit is too low to  allow  any
	      multi-threading,	the  limit  is ignored and xz will continue in
	      single-threaded mode.  Note that if  also	 --memlimit-decompress
	      is used, it will always apply to both single-threaded and multi-
	      threaded modes, and so the effective limit  for  multi-threading
	      will  never  be higher than the limit set with --memlimit-decom‐
	      press.

	      In contrast to the other	memory	usage  limit  options,	--mem‐
	      limit-mt-decompress=limit	 has  a system-specific default limit.
	      xz --info-memory can be used to see the current value.

	      This option and its default  value  exist	 because  without  any
	      limit  the  threaded decompressor could end up allocating an in‐
	      sane amount of memory with some input  files.   If  the  default
	      limit is too low on your system, feel free to increase the limit
	      but never set it to a value larger than the amount of usable RAM
	      as  with	appropriate  input  files  xz will attempt to use that
	      amount of memory even with a low number of threads.  Running out
	      of  memory  or  swapping	will not improve decompression perfor‐
	      mance.

	      See --memlimit-compress=limit for possible ways to  specify  the
	      limit.   Setting limit to 0 resets the limit to the default sys‐
	      tem-specific value.

       -M limit, --memlimit=limit, --memory=limit
	      This  is	equivalent  to	specifying   --memlimit-compress=limit
	      --memlimit-decompress=limit --memlimit-mt-decompress=limit.

       --no-adjust
	      Display  an  error  and exit if the memory usage limit cannot be
	      met without adjusting settings that affect the  compressed  out‐
	      put.   That is, this prevents xz from switching the encoder from
	      multi-threaded mode to single-threaded mode  and	from  reducing
	      the  LZMA2  dictionary  size.  Even when this option is used the
	      number of threads may be reduced to meet the memory usage	 limit
	      as that won't affect the compressed output.

	      Automatic adjusting is always disabled when creating raw streams
	      (--format=raw).

       -T threads, --threads=threads
	      Specify the number of worker threads to use.  Setting threads to
	      a special value 0 makes xz use up to as many threads as the pro‐
	      cessor(s) on the system support.	The actual number  of  threads
	      can  be  fewer  than threads if the input file is not big enough
	      for threading with the given settings or if using	 more  threads
	      would exceed the memory usage limit.

	      The  single-threaded and multi-threaded compressors produce dif‐
	      ferent output.  Single-threaded compressor will give the	small‐
	      est  file	 size but only the output from the multi-threaded com‐
	      pressor can be decompressed  using  multiple  threads.   Setting
	      threads to 1 will use the single-threaded mode.  Setting threads
	      to any other value, including 0,	will  use  the	multi-threaded
	      compressor even if the system supports only one hardware thread.
	      (xz 5.2.x used single-threaded mode in this situation.)

	      To use multi-threaded mode with only one thread, set threads  to
	      +1.   The	 +  prefix  has no effect with values other than 1.  A
	      memory usage limit can still make xz switch  to  single-threaded
	      mode  unless  --no-adjust is used.  Support for the + prefix was
	      added in xz 5.4.0.

	      If an automatic number of threads has been requested and no mem‐
	      ory  usage  limit has been specified, then a system-specific de‐
	      fault soft limit will be used to possibly limit  the  number  of
	      threads.	 It is a soft limit in sense that it is ignored if the
	      number of threads becomes one, thus a soft limit will never stop
	      xz  from	compressing or decompressing.  This default soft limit
	      will not make xz switch  from  multi-threaded  mode  to  single-
	      threaded	 mode.	  The  active  limits  can  be	seen  with  xz
	      --info-memory.

	      Currently the only threading method is to split the  input  into
	      blocks and compress them independently from each other.  The de‐
	      fault block size depends on the compression  level  and  can  be
	      overridden with the --block-size=size option.

	      Threaded decompression only works on files that contain multiple
	      blocks with size information in block headers.  All large enough
	      files compressed in multi-threaded mode meet this condition, but
	      files  compressed	 in  single-threaded  mode   don't   even   if
	      --block-size=size has been used.

	      The  default  value for threads is 0.  In xz 5.4.x and older the
	      default is 1.

   Custom compressor filter chains
       A custom filter chain allows specifying the compression settings in de‐
       tail  instead  of  relying  on  the settings associated to the presets.
       When a custom filter chain is specified, preset options (-0 ... -9  and
       --extreme)  earlier on the command line are forgotten.  If a preset op‐
       tion is specified after one or more custom filter  chain	 options,  the
       new  preset  takes effect and the custom filter chain options specified
       earlier are forgotten.

       A filter chain is comparable to piping on the command line.  When  com‐
       pressing, the uncompressed input goes to the first filter, whose output
       goes to the next filter (if any).  The output of the last  filter  gets
       written	to  the compressed file.  The maximum number of filters in the
       chain is four, but typically a filter chain has only one	 or  two  fil‐
       ters.

       Many filters have limitations on where they can be in the filter chain:
       some filters can work only as the last filter in the chain,  some  only
       as  a non-last filter, and some work in any position in the chain.  De‐
       pending on the filter, this limitation is either inherent to the filter
       design or exists to prevent security issues.

       A  custom filter chain can be specified in two different ways.  The op‐
       tions --filters=filters and --filters1=filters  ...  --filters9=filters
       allow specifying an entire filter chain in one option using the liblzma
       filter string syntax.  Alternatively, a filter chain can	 be  specified
       by  using  one  or more individual filter options in the order they are
       wanted in the filter chain.  That is, the order of the individual  fil‐
       ter  options is significant!  When decoding raw streams (--format=raw),
       the filter chain must be specified in the same order as it  was	speci‐
       fied  when compressing.	Any individual filter or preset options speci‐
       fied before the full chain option (--filters=filters) will  be  forgot‐
       ten.  Individual filters specified after the full chain option will re‐
       set the filter chain.

       Both the full and individual filter options  take  filter-specific  op‐
       tions  as a comma-separated list.  Extra commas in options are ignored.
       Every option has a default value, so specify those you want to change.

       To see the whole filter chain and options, use xz  -vv  (that  is,  use
       --verbose twice).  This works also for viewing the filter chain options
       used by presets.

       --filters=filters
	      Specify the full filter chain or a preset in  a  single  option.
	      Each filter can be separated by spaces or two dashes (--).  fil‐
	      ters may need to be quoted on the shell command line  so	it  is
	      parsed  as  a  single option.  To denote options, use : or =.  A
	      preset can be prefixed with a - and followed with zero  or  more
	      flags.   The  only supported flag is e to apply the same options
	      as --extreme.

       --filters1=filters ... --filters9=filters
	      Specify up to nine additional filter chains  that	 can  be  used
	      with --block-list.

	      For  example,  when compressing an archive with executable files
	      followed by text files, the executable part could use  a	filter
	      chain with a BCJ filter and the text part only the LZMA2 filter.

       --filters-help
	      Display  a  help	message	 describing how to specify presets and
	      custom filter chains in the --filters and --filters1=filters ...
	      --filters9=filters options, and exit successfully.

       --lzma1[=options]
       --lzma2[=options]
	      Add  LZMA1  or  LZMA2 filter to the filter chain.	 These filters
	      can be used only as the last filter in the chain.

	      LZMA1 is a legacy filter, which is supported almost  solely  due
	      to  the  legacy  .lzma  file  format, which supports only LZMA1.
	      LZMA2 is an updated version of LZMA1 to fix some	practical  is‐
	      sues  of	LZMA1.	 The .xz format uses LZMA2 and doesn't support
	      LZMA1 at all.  Compression speed and ratios of LZMA1  and	 LZMA2
	      are practically the same.

	      LZMA1 and LZMA2 share the same set of options:

	      preset=preset
		     Reset  all LZMA1 or LZMA2 options to preset.  Preset con‐
		     sist of an integer, which may be followed by  single-let‐
		     ter  preset  modifiers.   The integer can be from 0 to 9,
		     matching the command line options -0 ...  -9.   The  only
		     supported	modifier  is  currently e, which matches --ex‐
		     treme.  If no preset is specified, the default values  of
		     LZMA1 or LZMA2 options are taken from the preset 6.

	      dict=size
		     Dictionary (history buffer) size indicates how many bytes
		     of the recently processed uncompressed data  is  kept  in
		     memory.   The  algorithm tries to find repeating byte se‐
		     quences (matches) in the uncompressed data,  and  replace
		     them with references to the data currently in the dictio‐
		     nary.  The bigger	the  dictionary,  the  higher  is  the
		     chance to find a match.  Thus, increasing dictionary size
		     usually improves compression ratio, but a dictionary big‐
		     ger than the uncompressed file is waste of memory.

		     Typical  dictionary  size	is from 64 KiB to 64 MiB.  The
		     minimum is 4 KiB.	The maximum for	 compression  is  cur‐
		     rently 1.5 GiB (1536 MiB).	 The decompressor already sup‐
		     ports dictionaries up to one byte less than 4 GiB,	 which
		     is the maximum for the LZMA1 and LZMA2 stream formats.

		     Dictionary	 size and match finder (mf) together determine
		     the memory usage of the LZMA1 or LZMA2 encoder.  The same
		     (or bigger) dictionary size is required for decompressing
		     that was used when compressing, thus the memory usage  of
		     the  decoder  is  determined  by the dictionary size used
		     when compressing.	The .xz headers store  the  dictionary
		     size  either  as 2^n or 2^n + 2^(n-1), so these sizes are
		     somewhat preferred for compression.  Other sizes will get
		     rounded up when stored in the .xz headers.

	      lc=lc  Specify  the number of literal context bits.  The minimum
		     is 0 and the maximum is 4; the default is	3.   In	 addi‐
		     tion, the sum of lc and lp must not exceed 4.

		     All  bytes	 that cannot be encoded as matches are encoded
		     as literals.  That is, literals are  simply  8-bit	 bytes
		     that are encoded one at a time.

		     The  literal  coding makes an assumption that the highest
		     lc bits of the previous uncompressed byte correlate  with
		     the  next byte.  For example, in typical English text, an
		     upper-case letter is often followed by a lower-case  let‐
		     ter,  and	a lower-case letter is usually followed by an‐
		     other lower-case letter.  In the US-ASCII character  set,
		     the highest three bits are 010 for upper-case letters and
		     011 for lower-case letters.  When lc is at least  3,  the
		     literal coding can take advantage of this property in the
		     uncompressed data.

		     The default value (3) is usually good.  If you want maxi‐
		     mum compression, test lc=4.  Sometimes it helps a little,
		     and sometimes it makes compression worse.	If it makes it
		     worse, test lc=2 too.

	      lp=lp  Specify the number of literal position bits.  The minimum
		     is 0 and the maximum is 4; the default is 0.

		     Lp affects what kind of  alignment	 in  the  uncompressed
		     data is assumed when encoding literals.  See pb below for
		     more information about alignment.

	      pb=pb  Specify the number of position bits.  The	minimum	 is  0
		     and the maximum is 4; the default is 2.

		     Pb	 affects  what	kind  of alignment in the uncompressed
		     data is assumed in general.  The default means  four-byte
		     alignment (2^pb=2^2=4), which is often a good choice when
		     there's no better guess.

		     When the alignment is known, setting pb  accordingly  may
		     reduce  the  file	size a little.	For example, with text
		     files having one-byte  alignment  (US-ASCII,  ISO-8859-*,
		     UTF-8),  setting  pb=0  can improve compression slightly.
		     For UTF-16 text, pb=1 is a good choice.  If the alignment
		     is	 an  odd  number  like 3 bytes, pb=0 might be the best
		     choice.

		     Even though the assumed alignment can be adjusted with pb
		     and  lp,  LZMA1  and  LZMA2  still slightly favor 16-byte
		     alignment.	 It might be worth taking  into	 account  when
		     designing	file  formats that are likely to be often com‐
		     pressed with LZMA1 or LZMA2.

	      mf=mf  Match finder has a major effect on encoder speed,	memory
		     usage,  and  compression ratio.  Usually Hash Chain match
		     finders are faster than Binary Tree match	finders.   The
		     default  depends  on the preset: 0 uses hc3, 1–3 use hc4,
		     and the rest use bt4.

		     The following match finders are  supported.   The	memory
		     usage  formulas below are rough approximations, which are
		     closest to the reality when dict is a power of two.

		     hc3    Hash Chain with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 7.5 (if dict <= 16 MiB);
			    dict * 5.5 + 64 MiB (if dict > 16 MiB)

		     hc4    Hash Chain with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 7.5 (if dict <= 32 MiB);
			    dict * 6.5 (if dict > 32 MiB)

		     bt2    Binary Tree with 2-byte hashing
			    Minimum value for nice: 2
			    Memory usage: dict * 9.5

		     bt3    Binary Tree with 2- and 3-byte hashing
			    Minimum value for nice: 3
			    Memory usage:
			    dict * 11.5 (if dict <= 16 MiB);
			    dict * 9.5 + 64 MiB (if dict > 16 MiB)

		     bt4    Binary Tree with 2-, 3-, and 4-byte hashing
			    Minimum value for nice: 4
			    Memory usage:
			    dict * 11.5 (if dict <= 32 MiB);
			    dict * 10.5 (if dict > 32 MiB)

	      mode=mode
		     Compression mode specifies the method to analyze the data
		     produced  by  the match finder.  Supported modes are fast
		     and normal.  The default is fast for presets 0–3 and nor‐
		     mal for presets 4–9.

		     Usually  fast  is	used with Hash Chain match finders and
		     normal with Binary Tree match finders.  This is also what
		     the presets do.

	      nice=nice
		     Specify  what  is	considered  to	be a nice length for a
		     match.  Once a match of at least nice bytes is found, the
		     algorithm stops looking for possibly better matches.

		     Nice can be 2–273 bytes.  Higher values tend to give bet‐
		     ter compression ratio at the expense of speed.   The  de‐
		     fault depends on the preset.

	      depth=depth
		     Specify  the  maximum  search  depth in the match finder.
		     The default is the special value of 0,  which  makes  the
		     compressor determine a reasonable depth from mf and nice.

		     Reasonable depth for Hash Chains is 4–100 and 16–1000 for
		     Binary Trees.  Using very high values for depth can  make
		     the  encoder  extremely slow with some files.  Avoid set‐
		     ting the depth over 1000 unless you are prepared  to  in‐
		     terrupt  the  compression	in  case  it is taking far too
		     long.

	      When decoding raw streams (--format=raw), LZMA2 needs  only  the
	      dictionary size.	LZMA1 needs also lc, lp, and pb.

       --x86[=options]
       --arm[=options]
       --armthumb[=options]
       --arm64[=options]
       --powerpc[=options]
       --ia64[=options]
       --sparc[=options]
       --riscv[=options]
	      Add  a branch/call/jump (BCJ) filter to the filter chain.	 These
	      filters can be used only as a  non-last  filter  in  the	filter
	      chain.

	      A	 BCJ filter converts relative addresses in the machine code to
	      their absolute counterparts.  This doesn't change	 the  size  of
	      the  data	 but  it increases redundancy, which can help LZMA2 to
	      produce 0–15 % smaller .xz file.	The BCJ filters are always re‐
	      versible,	 so  using a BCJ filter for wrong type of data doesn't
	      cause any data loss, although it may make the compression	 ratio
	      slightly	worse.	 The  BCJ filters are very fast and use an in‐
	      significant amount of memory.

	      These BCJ filters have known problems related to the compression
	      ratio:

	      •	 Some  types of files containing executable code (for example,
		 object files, static libraries,  and  Linux  kernel  modules)
		 have  the  addresses  in  the instructions filled with filler
		 values.  These BCJ filters will still do the address  conver‐
		 sion, which will make the compression worse with these files.

	      •	 If a BCJ filter is applied on an archive, it is possible that
		 it makes the compression ratio worse than  not	 using	a  BCJ
		 filter.   For example, if there are similar or even identical
		 executables then filtering will likely make  the  files  less
		 similar  and thus compression is worse.  The contents of non-
		 executable files in the same  archive	can  matter  too.   In
		 practice  one has to try with and without a BCJ filter to see
		 which is better in each situation.

	      Different instruction sets have different	 alignment:  the  exe‐
	      cutable  file must be aligned to a multiple of this value in the
	      input data to make the filter work.

		     tab(;); l n l l n l.  Filter;Alignment;Notes x86;1;32-bit
		     or	  64-bit  x86  ARM;4;  ARM-Thumb;2;  ARM64;4;4096-byte
		     alignment is best PowerPC;4;Big endian only IA-64;16;Ita‐
		     nium SPARC;4; RISC-V;2;

	      Since  the  BCJ-filtered	data is usually compressed with LZMA2,
	      the compression ratio may be improved slightly if the LZMA2  op‐
	      tions are set to match the alignment of the selected BCJ filter.
	      Examples:

	      •	 IA-64 filter has 16-byte alignment so pb=4,lp=4,lc=0 is  good
		 with LZMA2 (2^4=16).

	      •	 RISC-V	 code  has  2-byte  or	4-byte	alignment depending on
		 whether the file contains 16-bit compressed instructions (the
		 C   extension).    When   16-bit   instructions   are	 used,
		 pb=2,lp=1,lc=3 or pb=1,lp=1,lc=3 is good.   When  16-bit  in‐
		 structions aren't present, pb=2,lp=2,lc=2 is the best.	 read‐
		 elf -h can be used to check if "RVC" appears on  the  "Flags"
		 line.

	      •	 ARM64 is always 4-byte aligned so pb=2,lp=2,lc=2 is the best.

	      •	 The  x86  filter is an exception.  It's usually good to stick
		 to LZMA2's defaults (pb=2,lp=0,lc=3) when compressing x86 ex‐
		 ecutables.

	      All BCJ filters support the same options:

	      start=offset
		     Specify the start offset that is used when converting be‐
		     tween relative and absolute addresses.  The  offset  must
		     be a multiple of the alignment of the filter (see the ta‐
		     ble above).  The default is zero.	In practice,  the  de‐
		     fault is good; specifying a custom offset is almost never
		     useful.

       --delta[=options]
	      Add the Delta filter to the filter chain.	 The Delta filter  can
	      be only used as a non-last filter in the filter chain.

	      Currently	 only simple byte-wise delta calculation is supported.
	      It can be useful when  compressing,  for	example,  uncompressed
	      bitmap  images or uncompressed PCM audio.	 However, special pur‐
	      pose algorithms may give significantly better results than Delta
	      +	 LZMA2.	  This is true especially with audio, which compresses
	      faster and better, for example, with flac(1).

	      Supported options:

	      dist=distance
		     Specify the distance of the delta calculation  in	bytes.
		     distance must be 1–256.  The default is 1.

		     For example, with dist=2 and eight-byte input A1 B1 A2 B3
		     A3 B5 A4 B7, the output will be A1 B1 01 02 01 02 01 02.

   Other options
       -q, --quiet
	      Suppress warnings and notices.  Specify this twice  to  suppress
	      errors too.  This option has no effect on the exit status.  That
	      is, even if a warning was suppressed, the exit status  to	 indi‐
	      cate a warning is still used.

       -v, --verbose
	      Be  verbose.   If	 standard error is connected to a terminal, xz
	      will display a progress indicator.  Specifying  --verbose	 twice
	      will give even more verbose output.

	      The progress indicator shows the following information:

	      •	 Completion  percentage is shown if the size of the input file
		 is known.  That is, the percentage cannot be shown in pipes.

	      •	 Amount of compressed data produced (compressing) or  consumed
		 (decompressing).

	      •	 Amount	 of  uncompressed  data consumed (compressing) or pro‐
		 duced (decompressing).

	      •	 Compression ratio, which is calculated by dividing the amount
		 of  compressed	 data processed so far by the amount of uncom‐
		 pressed data processed so far.

	      •	 Compression or decompression speed.  This is measured as  the
		 amount	 of  uncompressed  data consumed (compression) or pro‐
		 duced (decompression) per second.  It is shown	 after	a  few
		 seconds have passed since xz started processing the file.

	      •	 Elapsed time in the format M:SS or H:MM:SS.

	      •	 Estimated  remaining  time is shown only when the size of the
		 input file is known and a  couple  of	seconds	 have  already
		 passed	 since	xz  started  processing the file.  The time is
		 shown in a less precise format which never  has  any  colons,
		 for example, 2 min 30 s.

	      When  standard  error  is not a terminal, --verbose will make xz
	      print the filename, compressed size, uncompressed size, compres‐
	      sion  ratio,  and	 possibly also the speed and elapsed time on a
	      single line to standard error after compressing or decompressing
	      the file.	 The speed and elapsed time are included only when the
	      operation took at least a few seconds.  If the operation	didn't
	      finish,  for example, due to user interruption, also the comple‐
	      tion percentage is printed if the size  of  the  input  file  is
	      known.

       -Q, --no-warn
	      Don't set the exit status to 2 even if a condition worth a warn‐
	      ing was detected.	 This  option  doesn't	affect	the  verbosity
	      level,  thus  both  --quiet and --no-warn have to be used to not
	      display warnings and to not alter the exit status.

       --robot
	      Print messages in a machine-parsable format.  This  is  intended
	      to  ease	writing	 frontends  that want to use xz instead of li‐
	      blzma, which may be the case with various scripts.   The	output
	      with  this  option  enabled  is meant to be stable across xz re‐
	      leases.  See the section ROBOT MODE for details.

       --info-memory
	      Display, in human-readable  format,  how	much  physical	memory
	      (RAM)  and  how  many processor threads xz thinks the system has
	      and the memory usage limits for compression  and	decompression,
	      and exit successfully.

       -h, --help
	      Display  a  help	message	 describing the most commonly used op‐
	      tions, and exit successfully.

       -H, --long-help
	      Display a help message describing all features of xz,  and  exit
	      successfully

       -V, --version
	      Display  the  version number of xz and liblzma in human readable
	      format.  To get machine-parsable output, specify --robot	before
	      --version.

ROBOT MODE
       The robot mode is activated with the --robot option.  It makes the out‐
       put of xz easier to parse by other programs.  Currently --robot is sup‐
       ported  only  together  with --list, --filters-help, --info-memory, and
       --version.  It will be supported for compression and  decompression  in
       the future.

   List mode
       xz --robot --list uses tab-separated output.  The first column of every
       line has a string that indicates the type of the information  found  on
       that line:

       name   This is always the first line when starting to list a file.  The
	      second column on the line is the filename.

       file   This line contains overall information about the .xz file.  This
	      line is always printed after the name line.

       stream This line type is used only when --verbose was specified.	 There
	      are as many stream lines as there are streams in the .xz file.

       block  This line type is used only when --verbose was specified.	 There
	      are  as  many  block  lines as there are blocks in the .xz file.
	      The block lines are shown after all the stream lines;  different
	      line types are not interleaved.

       summary
	      This  line type is used only when --verbose was specified twice.
	      This line is printed after all block lines.  Like the file line,
	      the  summary  line  contains  overall  information about the .xz
	      file.

       totals This line is always the very last line of the list  output.   It
	      shows the total counts and sizes.

       The columns of the file lines:
	      2.  Number of streams in the file
	      3.  Total number of blocks in the stream(s)
	      4.  Compressed size of the file
	      5.  Uncompressed size of the file
	      6.  Compression  ratio,  for  example,  0.123.  If ratio is over
		  9.999, three dashes (---) are displayed instead of  the  ra‐
		  tio.
	      7.  Comma-separated  list of integrity check names.  The follow‐
		  ing strings are used for the known check types: None, CRC32,
		  CRC64,  and  SHA-256.	 For unknown check types, Unknown-N is
		  used, where N is the Check ID as a decimal  number  (one  or
		  two digits).
	      8.  Total size of stream padding in the file

       The columns of the stream lines:
	      2.  Stream number (the first stream is 1)
	      3.  Number of blocks in the stream
	      4.  Compressed start offset
	      5.  Uncompressed start offset
	      6.  Compressed size (does not include stream padding)
	      7.  Uncompressed size
	      8.  Compression ratio
	      9.  Name of the integrity check
	      10. Size of stream padding

       The columns of the block lines:
	      2.  Number of the stream containing this block
	      3.  Block	 number	 relative  to the beginning of the stream (the
		  first block is 1)
	      4.  Block number relative to the beginning of the file
	      5.  Compressed start offset relative to  the  beginning  of  the
		  file
	      6.  Uncompressed	start  offset relative to the beginning of the
		  file
	      7.  Total compressed size of the block (includes headers)
	      8.  Uncompressed size
	      9.  Compression ratio
	      10. Name of the integrity check

       If --verbose was specified twice, additional columns  are  included  on
       the  block lines.  These are not displayed with a single --verbose, be‐
       cause getting this information requires many  seeks  and	 can  thus  be
       slow:
	      11. Value of the integrity check in hexadecimal
	      12. Block header size
	      13. Block	 flags:	 c  indicates that compressed size is present,
		  and u indicates that uncompressed size is present.   If  the
		  flag	is  not	 set,  a dash (-) is shown instead to keep the
		  string length fixed.	New flags may be added to the  end  of
		  the string in the future.
	      14. Size	of  the	 actual compressed data in the block (this ex‐
		  cludes the block header, block padding, and check fields)
	      15. Amount of memory (in	bytes)	required  to  decompress  this
		  block with this xz version
	      16. Filter  chain.   Note	 that most of the options used at com‐
		  pression time cannot be known, because only the options that
		  are needed for decompression are stored in the .xz headers.

       The columns of the summary lines:
	      2.  Amount of memory (in bytes) required to decompress this file
		  with this xz version
	      3.  yes or no indicating if all block  headers  have  both  com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      4.  Minimum xz version required to decompress the file

       The columns of the totals line:
	      2.  Number of streams
	      3.  Number of blocks
	      4.  Compressed size
	      5.  Uncompressed size
	      6.  Average compression ratio
	      7.  Comma-separated  list	 of  integrity	check  names that were
		  present in the files
	      8.  Stream padding size
	      9.  Number of files.  This is here to keep the order of the ear‐
		  lier columns the same as on file lines.

       If  --verbose  was  specified twice, additional columns are included on
       the totals line:
	      10. Maximum amount of memory (in bytes) required	to  decompress
		  the files with this xz version
	      11. yes  or  no  indicating  if all block headers have both com‐
		  pressed size and uncompressed size stored in them
	      Since xz 5.1.2alpha:
	      12. Minimum xz version required to decompress the file

       Future versions may add new line types and new columns can be added  to
       the existing line types, but the existing columns won't be changed.

   Filters help
       xz --robot --filters-help prints the supported filters in the following
       format:

       filter:option=<value>,option=<value>...

       filter Name of the filter

       option Name of a filter specific option

       value  Numeric value ranges appear as <min-max>.	 String value  choices
	      are shown within < > and separated by a | character.

       Each filter is printed on its own line.

   Memory limit information
       xz  --robot  --info-memory prints a single line with multiple tab-sepa‐
       rated columns:

       1.  Total amount of physical memory (RAM) in bytes.

       2.  Memory usage limit for compression in bytes	(--memlimit-compress).
	   A  special  value of 0 indicates the default setting which for sin‐
	   gle-threaded mode is the same as no limit.

       3.  Memory usage limit for decompression	 in  bytes  (--memlimit-decom‐
	   press).   A	special value of 0 indicates the default setting which
	   for single-threaded mode is the same as no limit.

       4.  Since xz 5.3.4alpha: Memory usage for multi-threaded	 decompression
	   in  bytes (--memlimit-mt-decompress).  This is never zero because a
	   system-specific default value shown in the column 5 is used	if  no
	   limit  has  been  specified explicitly.  This is also never greater
	   than the value in the column 3 even if  a  larger  value  has  been
	   specified with --memlimit-mt-decompress.

       5.  Since  xz  5.3.4alpha: A system-specific default memory usage limit
	   that is used to limit the number of threads when  compressing  with
	   an  automatic  number  of threads (--threads=0) and no memory usage
	   limit has been specified (--memlimit-compress).  This is also  used
	   as the default value for --memlimit-mt-decompress.

       6.  Since xz 5.3.4alpha: Number of available processor threads.

       In  the	future,	 the  output of xz --robot --info-memory may have more
       columns, but never more than a single line.

   Version
       xz --robot --version prints the version number of xz and liblzma in the
       following format:

       XZ_VERSION=XYYYZZZS
       LIBLZMA_VERSION=XYYYZZZS

       X      Major version.

       YYY    Minor  version.  Even numbers are stable.	 Odd numbers are alpha
	      or beta versions.

       ZZZ    Patch level for stable releases or just a counter	 for  develop‐
	      ment releases.

       S      Stability.  0 is alpha, 1 is beta, and 2 is stable.  S should be
	      always 2 when YYY is even.

       XYYYZZZS are the same on both lines if xz and liblzma are from the same
       XZ Utils release.

       Examples: 4.999.9beta is 49990091 and 5.0.0 is 50000002.

EXIT STATUS
       0      All is good.

       1      An error occurred.

       2      Something	 worth	a  warning  occurred, but no actual errors oc‐
	      curred.

       Notices (not warnings or errors) printed on standard error don't affect
       the exit status.

ENVIRONMENT
       xz  parses  space-separated lists of options from the environment vari‐
       ables XZ_DEFAULTS and XZ_OPT, in this order, before parsing the options
       from  the command line.	Note that only options are parsed from the en‐
       vironment variables; all non-options are silently ignored.  Parsing  is
       done  with getopt_long(3) which is used also for the command line argu‐
       ments.

       XZ_DEFAULTS
	      User-specific or system-wide default options.  Typically this is
	      set in a shell initialization script to enable xz's memory usage
	      limiter by default.  Excluding shell initialization scripts  and
	      similar  special	cases,	scripts must never set or unset XZ_DE‐
	      FAULTS.

       XZ_OPT This is for passing options to xz when it is not possible to set
	      the  options  directly on the xz command line.  This is the case
	      when xz is run by a script or tool, for example, GNU tar(1):

		     XZ_OPT=-2v tar caf foo.tar.xz foo

	      Scripts may use XZ_OPT, for example, to set script-specific  de‐
	      fault  compression  options.   It	 is still recommended to allow
	      users to override XZ_OPT if that is reasonable.  For example, in
	      sh(1) scripts one may use something like this:

		     XZ_OPT=${XZ_OPT-"-7e"}
		     export XZ_OPT

LZMA UTILS COMPATIBILITY
       The  command  line  syntax of xz is practically a superset of lzma, un‐
       lzma, and lzcat as found from LZMA Utils 4.32.x.	 In most cases, it  is
       possible	 to replace LZMA Utils with XZ Utils without breaking existing
       scripts.	 There are some incompatibilities though, which may  sometimes
       cause problems.

   Compression preset levels
       The  numbering  of the compression level presets is not identical in xz
       and LZMA Utils.	The most important difference is how dictionary	 sizes
       are  mapped  to different presets.  Dictionary size is roughly equal to
       the decompressor memory usage.

	      tab(;); c c c c n n.  Level;xz;LZMA Utils	 -0;256	 KiB;N/A  -1;1
	      MiB;64  KiB  -2;2 MiB;1 MiB -3;4 MiB;512 KiB -4;4 MiB;1 MiB -5;8
	      MiB;2 MiB -6;8 MiB;4 MiB -7;16 MiB;8 MiB -8;32 MiB;16 MiB	 -9;64
	      MiB;32 MiB

       The dictionary size differences affect the compressor memory usage too,
       but there are some other differences between LZMA Utils and  XZ	Utils,
       which make the difference even bigger:

	      tab(;);  c  c  c c n n.  Level;xz;LZMA Utils 4.32.x -0;3 MiB;N/A
	      -1;9 MiB;2 MiB -2;17 MiB;12 MiB -3;32 MiB;12  MiB	 -4;48	MiB;16
	      MiB  -5;94  MiB;26 MiB -6;94 MiB;45 MiB -7;186 MiB;83 MiB -8;370
	      MiB;159 MiB -9;674 MiB;311 MiB

       The default preset level in LZMA Utils is -7 while in XZ	 Utils	it  is
       -6, so both use an 8 MiB dictionary by default.

   Streamed vs. non-streamed .lzma files
       The  uncompressed  size	of the file can be stored in the .lzma header.
       LZMA Utils does that when compressing regular files.   The  alternative
       is  to  mark  that  uncompressed size is unknown and use end-of-payload
       marker to indicate where the decompressor should stop.  LZMA Utils uses
       this  method when uncompressed size isn't known, which is the case, for
       example, in pipes.

       xz supports decompressing .lzma files with  or  without	end-of-payload
       marker,	but  all  .lzma	 files	created	 by xz will use end-of-payload
       marker and have uncompressed  size  marked  as  unknown	in  the	 .lzma
       header.	 This may be a problem in some uncommon situations.  For exam‐
       ple, a .lzma decompressor in an embedded device might  work  only  with
       files  that have known uncompressed size.  If you hit this problem, you
       need to use LZMA Utils or LZMA SDK to create .lzma files with known un‐
       compressed size.

   Unsupported .lzma files
       The .lzma format allows lc values up to 8, and lp values up to 4.  LZMA
       Utils can decompress files with any lc and lp, but always creates files
       with  lc=3  and	lp=0.  Creating files with other lc and lp is possible
       with xz and with LZMA SDK.

       The implementation of the LZMA1 filter in liblzma requires that the sum
       of  lc  and lp must not exceed 4.  Thus, .lzma files, which exceed this
       limitation, cannot be decompressed with xz.

       LZMA Utils creates only .lzma files which have a dictionary size of 2^n
       (a power of 2) but accepts files with any dictionary size.  liblzma ac‐
       cepts only .lzma files which have a dictionary size of  2^n  or	2^n  +
       2^(n-1).	  This	is  to	decrease  false positives when detecting .lzma
       files.

       These limitations shouldn't be a problem in practice, since practically
       all  .lzma  files  have been compressed with settings that liblzma will
       accept.

   Trailing garbage
       When decompressing, LZMA Utils silently	ignore	everything  after  the
       first  .lzma  stream.   In  most	 situations, this is a bug.  This also
       means that LZMA Utils don't support  decompressing  concatenated	 .lzma
       files.

       If  there  is  data left after the first .lzma stream, xz considers the
       file to be corrupt unless --single-stream was used.  This may break ob‐
       scure scripts which have assumed that trailing garbage is ignored.

NOTES
   Compressed output may vary
       The  exact  compressed output produced from the same uncompressed input
       file may vary between XZ Utils versions even if compression options are
       identical.  This is because the encoder can be improved (faster or bet‐
       ter compression) without affecting the file  format.   The  output  can
       vary  even  between  different  builds of the same XZ Utils version, if
       different build options are used.

       The above means that once --rsyncable has been implemented, the result‐
       ing  files won't necessarily be rsyncable unless both old and new files
       have been compressed with the same xz version.	This  problem  can  be
       fixed if a part of the encoder implementation is frozen to keep rsynca‐
       ble output stable across xz versions.

   Embedded .xz decompressors
       Embedded .xz decompressor implementations like XZ Embedded don't neces‐
       sarily support files created with integrity check types other than none
       and  crc32.   Since  the	 default  is  --check=crc64,  you   must   use
       --check=none or --check=crc32 when creating files for embedded systems.

       Outside	embedded systems, all .xz format decompressors support all the
       check types, or at least are able to decompress the file without	 veri‐
       fying the integrity check if the particular check is not supported.

       XZ  Embedded supports BCJ filters, but only with the default start off‐
       set.

EXAMPLES
   Basics
       Compress the file foo into foo.xz using the default  compression	 level
       (-6), and remove foo if compression is successful:

	      xz foo

       Decompress  bar.xz  into bar and don't remove bar.xz even if decompres‐
       sion is successful:

	      xz -dk bar.xz

       Create baz.tar.xz with the preset -4e (-4 --extreme), which  is	slower
       than  the  default -6, but needs less memory for compression and decom‐
       pression (48 MiB and 5 MiB, respectively):

	      tar cf - baz | xz -4e > baz.tar.xz

       A mix of compressed and uncompressed files can be decompressed to stan‐
       dard output with a single command:

	      xz -dcf a.txt b.txt.xz c.txt d.txt.lzma > abcd.txt

   Parallel compression of many files
       On  GNU	and *BSD, find(1) and xargs(1) can be used to parallelize com‐
       pression of many files:

	      find . -type f \! -name '*.xz' -print0 \
		  | xargs -0r -P4 -n16 xz -T1

       The -P option to xargs(1) sets the number  of  parallel	xz  processes.
       The best value for the -n option depends on how many files there are to
       be compressed.  If there are only a couple of files, the	 value	should
       probably be 1; with tens of thousands of files, 100 or even more may be
       appropriate to reduce the number of xz  processes  that	xargs(1)  will
       eventually create.

       The option -T1 for xz is there to force it to single-threaded mode, be‐
       cause xargs(1) is used to control the amount of parallelization.

   Robot mode
       Calculate how many bytes have been saved	 in  total  after  compressing
       multiple files:

	      xz --robot --list *.xz | awk '/^totals/{print $5-$4}'

       A  script may want to know that it is using new enough xz.  The follow‐
       ing sh(1) script checks that the version number of the xz  tool	is  at
       least  5.0.0.   This method is compatible with old beta versions, which
       didn't support the --robot option:

	      if ! eval "$(xz --robot --version 2> /dev/null)" ||
		      [ "$XZ_VERSION" -lt 50000002 ]; then
		  echo "Your xz is too old."
	      fi
	      unset XZ_VERSION LIBLZMA_VERSION

       Set a memory usage limit for decompression using XZ_OPT, but if a limit
       has already been set, don't increase it:

	      NEWLIM=$((123 << 20))  # 123 MiB
	      OLDLIM=$(xz --robot --info-memory | cut -f3)
	      if [ $OLDLIM -eq 0 -o $OLDLIM -gt $NEWLIM ]; then
		  XZ_OPT="$XZ_OPT --memlimit-decompress=$NEWLIM"
		  export XZ_OPT
	      fi

   Custom compressor filter chains
       The  simplest  use for custom filter chains is customizing a LZMA2 pre‐
       set.  This can be useful, because the presets cover only	 a  subset  of
       the potentially useful combinations of compression settings.

       The  CompCPU columns of the tables from the descriptions of the options
       -0 ... -9 and --extreme are  useful  when  customizing  LZMA2  presets.
       Here are the relevant parts collected from those two tables:

	      tab(;);  c  c n n.  Preset;CompCPU -0;0 -1;1 -2;2 -3;3 -4;4 -5;5
	      -6;6 -5e;7 -6e;8

       If you know that a file requires somewhat big dictionary (for  example,
       32 MiB)	to  compress well, but you want to compress it quicker than xz
       -8 would do, a preset with a low CompCPU value (for example, 1) can  be
       modified to use a bigger dictionary:

	      xz --lzma2=preset=1,dict=32MiB foo.tar

       With  certain  files,  the above command may be faster than xz -6 while
       compressing significantly better.  However, it must be emphasized  that
       only some files benefit from a big dictionary while keeping the CompCPU
       value low.  The most obvious situation, where a big dictionary can help
       a  lot,	is  an archive containing very similar files of at least a few
       megabytes each.	The dictionary size has	 to  be	 significantly	bigger
       than  any  individual file to allow LZMA2 to take full advantage of the
       similarities between consecutive files.

       If very high compressor and decompressor memory usage is fine, and  the
       file  being compressed is at least several hundred megabytes, it may be
       useful to use an even bigger dictionary than the	 64  MiB  that	xz  -9
       would use:

	      xz -vv --lzma2=dict=192MiB big_foo.tar

       Using -vv (--verbose --verbose) like in the above example can be useful
       to see the memory requirements of the compressor and decompressor.  Re‐
       member that using a dictionary bigger than the size of the uncompressed
       file is waste of memory, so the above command isn't  useful  for	 small
       files.

       Sometimes  the  compression  time  doesn't matter, but the decompressor
       memory usage has to be kept low, for example, to make  it  possible  to
       decompress  the file on an embedded system.  The following command uses
       -6e (-6 --extreme) as a base and sets the dictionary  to	 only  64 KiB.
       The  resulting  file  can  be decompressed with XZ Embedded (that's why
       there is --check=crc32) using about 100 KiB of memory.

	      xz --check=crc32 --lzma2=preset=6e,dict=64KiB foo

       If you want to squeeze out as many bytes	 as  possible,	adjusting  the
       number  of  literal  context bits (lc) and number of position bits (pb)
       can sometimes help.  Adjusting the number of literal position bits (lp)
       might help too, but usually lc and pb are more important.  For example,
       a source code archive contains mostly US-ASCII text, so something  like
       the following might give slightly (like 0.1 %) smaller file than xz -6e
       (try also without lc=4):

	      xz --lzma2=preset=6e,pb=0,lc=4 source_code.tar

       Using another filter together with LZMA2 can improve  compression  with
       certain file types.  For example, to compress a x86-32 or x86-64 shared
       library using the x86 BCJ filter:

	      xz --x86 --lzma2 libfoo.so

       Note that the order of the filter options is significant.  If --x86  is
       specified after --lzma2, xz will give an error, because there cannot be
       any filter after LZMA2, and also because the x86 BCJ filter  cannot  be
       used as the last filter in the chain.

       The  Delta filter together with LZMA2 can give good results with bitmap
       images.	It should usually beat PNG, which has a few more advanced fil‐
       ters than simple delta but uses Deflate for the actual compression.

       The  image  has to be saved in uncompressed format, for example, as un‐
       compressed TIFF.	 The distance parameter of the Delta filter is set  to
       match  the number of bytes per pixel in the image.  For example, 24-bit
       RGB bitmap needs dist=3, and it is also good to pass pb=0 to  LZMA2  to
       accommodate the three-byte alignment:

	      xz --delta=dist=3 --lzma2=pb=0 foo.tiff

       If  multiple  images  have been put into a single archive (for example,
       .tar), the Delta filter will work on that too as	 long  as  all	images
       have the same number of bytes per pixel.

SEE ALSO
       xzdec(1),   xzdiff(1),	xzgrep(1),   xzless(1),	  xzmore(1),  gzip(1),
       bzip2(1), 7z(1)

       XZ Utils: <https://tukaani.org/xz/>
       XZ Embedded: <https://tukaani.org/xz/embedded.html>
       LZMA SDK: <https://7-zip.org/sdk.html>



Tukaani				  2024-12-30				 XZ(1)