182 lines
5.3 KiB
Groff
182 lines
5.3 KiB
Groff
.\" $NetBSD: pigz.1,v 1.5 2014/06/15 19:41:04 wiz Exp $
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.Dd June 15, 2014
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.Dt PIGZ 1
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.Os
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.Sh NAME
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.Nm pigz ,
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.Nm unpigz
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.Nd compress or expand files
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.Sh SYNOPSIS
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.Nm
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.Op Fl 0..9cdFfhiKkLlNnqORrTtz
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.Op Fl 11
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.Op Fl b Ar blocksize
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.Op Fl I Ar iterations
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.Op Fl M Ar maxsplits
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.Op Fl p Ar threads
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.Op Fl S Ar suffix
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.Op Ar
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.Nm unpigz
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.Op Fl cfhiKkLlNnqRrTtz
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.Op Fl b Ar blocksize
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.Op Fl p Ar threads
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.Op Fl S Ar suffix
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.Op Ar
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.Sh DESCRIPTION
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.Nm
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compresses using threads to make use of multiple processors and cores.
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The input is broken up into 128 KB chunks with each compressed in parallel.
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The individual check value for each chunk is also calculated in parallel.
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The compressed data is written in order to the output, and a combined check
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value is calculated from the individual check values.
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.Pp
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The compressed data format generated is in the gzip, zlib, or single-entry
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zip format using the deflate compression method.
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The compression produces
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partial raw deflate streams which are concatenated by a single write thread
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and wrapped with the appropriate header and trailer, where the trailer
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contains the combined check value.
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.Pp
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Each partial raw deflate stream is terminated by an empty stored block
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(using the
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.Dv Z_SYNC_FLUSH
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option of
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.Xr zlib 3 ) ,
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in order to end that partial bit stream at a byte boundary.
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That allows the partial streams to be concatenated simply as sequences
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of bytes.
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This adds a very small four to five byte overhead to the output for
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each input chunk.
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.Pp
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The default input block size is 128K, but can be changed with the
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.Fl b
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option.
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The number of compress threads is set by default to the number
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of online processors, which can be changed using the
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.Fl p
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option.
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Specifying
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.Fl p Ar 1
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avoids the use of threads entirely.
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.Pp
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The input blocks, while compressed independently, have the last 32K of the
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previous block loaded as a preset dictionary to preserve the compression
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effectiveness of deflating in a single thread.
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This can be turned off using the
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.Fl i
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or
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.Fl Fl independent
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option, so that the blocks can be decompressed
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independently for partial error recovery or for random access.
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.Pp
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Decompression can't be parallelized, at least not without specially prepared
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deflate streams for that purpose.
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As a result,
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.Nm
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uses a single thread (the main thread) for decompression, but will
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create three other threads for reading, writing, and check
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calculation, which can speed up decompression under some
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circumstances.
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Parallel decompression can be turned off by specifying one process
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.Fl ( dp Ar 1
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or
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.Fl tp Ar 1 ) .
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.Pp
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Compressed files can be restored to their original form using
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.Nm pigz Fl d
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or
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.Nm unpigz .
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.Sh OPTIONS
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.Bl -tag -width XXiXXXindependentXX
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.It Fl #, Fl Fl fast, Fl Fl best
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Regulate the speed of compression using the specified digit
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.Ar # ,
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where
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.Fl 1
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or
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.Fl Fl fast
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indicates the fastest compression method (less compression)
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and
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.Fl 9
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or
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.Fl Fl best
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indicates the slowest compression method (best compression).
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.Fl 0
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is no compression.
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.Fl 11
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gives a few percent better compression at a severe cost in execution time.
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The default is
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.Fl 6 .
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.It Fl b, Fl Fl blocksize Ar mmm
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Set compression block size to
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.Ar mmm
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K (default 128KiB).
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.It Fl c, Fl Fl stdout, Fl Fl to-stdout
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Write all processed output to stdout (won't delete).
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.It Fl d, Fl Fl decompress, Fl Fl uncompress
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Decompress the compressed input.
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.It Fl F, Fl Fl first
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If compressing at level 11, do iterations first, before block split (default is last).
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.It Fl f, Fl Fl force
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Force overwrite, compress .gz, links, and to terminal.
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.It Fl h, Fl Fl help
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Display a help screen and quit.
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.It Fl I, Fl Fl iterations Ar n
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If compressing at level 11, number of iterations for optimization (default 15).
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.It Fl i, Fl Fl independent
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Compress blocks independently for damage recovery.
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.It Fl K, Fl Fl zip
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Compress to PKWare zip (.zip) single entry format.
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.It Fl k, Fl Fl keep
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Do not delete original file after processing.
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.It Fl L, Fl Fl license
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Display the
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.Nm pigz
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license and quit.
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.It Fl l, Fl Fl list
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List the contents of the compressed input.
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.It Fl M, Fl Fl maxsplits Ar n
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If compressing at level 11, maximum number of split blocks (default 15).
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.It Fl N, Fl Fl name
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Store/restore file name and mod time in/from header.
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.It Fl n, Fl Fl no-name
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Do not store or restore file name in/from header.
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.It Fl O, Fl Fl oneblock
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If compressing at level 11, do not split into smaller blocks (default is
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block splitting).
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.It Fl p, Fl Fl processes Ar n
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Allow up to n processes (default is the number of online processors)
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.It Fl q, Fl Fl quiet, Fl Fl silent
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Print no messages, even on error.
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.It Fl R, Fl Fl rsyncable
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Input-determined block locations for rsync.
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.It Fl r, Fl Fl recursive
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Process the contents of all subdirectories.
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.It Fl S, Fl Fl suffix Ar .sss
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Use suffix
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.Ar .sss
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instead of
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.Pa .gz
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(for compression).
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.It Fl T, Fl Fl no-time
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Do not store or restore mod time in/from header.
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.It Fl t, Fl Fl test
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Test the integrity of the compressed input.
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.It Fl V, Fl Fl version
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Show the version of pigz.
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.It Fl v, Fl Fl verbose
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Provide more verbose output.
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.It Fl z, Fl Fl zlib
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Compress to zlib
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.Pq Pa .zz
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instead of gzip format.
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.El
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.Sh COPYRIGHT NOTICE
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This software is provided 'as-is', without any express or implied
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warranty.
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In no event will the author be held liable for any damages
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arising from the use of this software.
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.Pp
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Copyright (C) 2007, 2008, 2009, 2010
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.An Mark Adler Aq Mt madler@alumni.caltech.edu
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