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