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LZMA(1)								       LZMA(1)

NAME
       lzma, unlzma, lzcat - LZMA compression and decompression tool

SYNOPSIS
       lzma [-123456789cdefhkLqtvV] [-S suffix] [filenames ...]
       unlzma [-cfhkLqtvV] [-S suffix] [filenames ...]
       lzcat [-fhLqV] [filenames ...]

DESCRIPTION
       LZMA  (Lempel-Ziv-Markov	 chain-Algorithm)  is  an  improved version of
       famous LZ77 compression algorithm. It was improved in  way  of  maximum
       increasing  of  compression ratio, keeping high decompression speed and
       low memory requirements for decompressing.

       lzma command line tool has a similar interface to gzip(1) and  bzip2(1)
       and  is intended to make use of LZMA compression easy for the users who
       are already familiar with gzip and bzip2.

       In this manual lzma is compared mostly to bzip2 because	that  is  cur‐
       rently  one of the most widely used free software to compress tar files
       made for distribution.  Comparing lzma to gzip is not practical because
       neither	lzma  nor bzip2 can compete with gzip in compression speed. On
       the other hand the compression ratio of gzip is worse than of lzma  and
       bzip2.

       lzma  provides  notably	better compression ratio than bzip2 especially
       with files having other than plain text content. The other advantage of
       lzma  is fast decompression which is many times quicker than bzip2. The
       major disadvantage is that achieving  the  highest  compression	ratios
       requires	 extensive  amount of system resources, both CPU time and RAM.
       Also software to handle LZMA  compressed	 files	is  not	 installed  by
       default on most distributions.

       When compressing or decompressing with lzma, the new file will have the
       same ownership information, permissions and timestamps as the  original
       file.  However  the  this information is not stored into the compressed
       file like gzip does.

STREAMED VS. NON-STREAMED
       LZMA files can be either streamed or non-streamed.  Non-streamed	 files
       are  created  only when the size of the file being compressed is known.
       In practice this means that the source file must be a regular file.  In
       other  words,  if  compressing  from the standard input or from a named
       pipe (fifo) the compressed file will always be streamed.

       Both streamed and non-streamed files are	 compressed  identically;  the
       only  differences  are  found from the beginnings and ends of LZMA com‐
       pressed files: Non-streamed files contain the uncompressed size of  the
       file  in	 the  LZMA  file header; streamed files have uncompressed size
       marked as unknown. To know where to stop decoding, streamed files  have
       a  special  End	Of  Stream marker at the end of the LZMA file. The EOS
       marker makes streamed files five or six bytes bigger than non-streamed.

       So in practice creating non-streamed files has two advantages:  1)  the
       compressed  file is a few bytes smaller and 2) the uncompressed size of
       the file can be checked without decompressing the file.

OPTIONS
       Short options can be grouped like -cd.

       -c --stdout --to-stdout
	      The output is written to the standard output. The original files
	      are  kept	 unchanged.  When  compressing	to the standard output
	      there can be only one input file. This option  is	 implied  when
	      input  is	 read from the standard input or the script is invoked
	      as lzcat.

       -d --decompress --uncompress
	      Force decompression regardless of the invocation name. This  the
	      default when called as unlzma or lzcat.

       -f --force
	      Force compression or decompression even if source file is a sym‐
	      link, target exists, or target is a  terminal.  In  contrast  to
	      gzip  and	 bzip2,	 if  input data is not in LZMA format, --force
	      does not make lzma behave like cat.  lzma never prompts if  tar‐
	      get  file	 should be overwritten; existing files are skipped or,
	      in case of --force, overwritten.

       -h --help
	      Show a summary of supported options and quit.

       -k --keep
	      Do not delete the input files after  compression	or  decompres‐
	      sion.

       -L --license
	      Show licensing information of lzma.

       -q --quiet
	      Suppress	all  warnings.	You can still check the exit status to
	      detect if a warning had been shown.

       -S --suffix .suf
	      Use .suf instead of the default .lzma.   A  null	suffix	forces
	      unlzma to decompress all the given files regardless of the file‐
	      name suffix.

       -t --test
	      Check the integrity of the compressed file(s). Without --verbose
	      no output is produced if no errors are found.

       -v --verbose
	      Show  the	 filename  and	percentage reduction of each processes
	      file.

       -V --version
	      Show the version number of lzma.

       -z --compress
	      Force compression regardless of the invocation name.

       -1 .. -9
	      Set the compression ratio. These options	have  no  effect  when
	      decompressing.

       --fast Alias to -1.

       --best Alias to -9.


DIAGNOSTICS
       Exit status:
       0 - Everything OK.
       1 - An error occurred.
       2 - Something worth a warning happened but no errors.

       It  can	be  especially useful with tar(1) patched to support LZMA com‐
       pression.

AUTHORS
       The LZMA algorithm and the implementation used in LZMA utils was devel‐
       oped  by	 Igor Pavlov. The original code is available in LZMA SDK which
       can be found from http://7-zip.org/sdk.html .

       lzma   command	line   tool   was   written   by    Ville    Koskinen.
       http://tukaani.org/lzma/

       This manual page is inspired by manual pages of gzip and bzip2.

SEE ALSO
       gzip(1), bzip2(1)

LZMA utils			  23 Dec 2005			       LZMA(1)
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