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.TH PIGZ 1 local | ||
.SH NAME | ||
pigz, unpigz \- compress or expand files | ||
.SH SYNOPSIS | ||
.ll +8 | ||
.B pigz | ||
.RB [ " \-cdfhikKlLnNqrRtTz0..9 " ] | ||
[ | ||
.B -b | ||
.I blocksize | ||
] | ||
[ | ||
.B -p | ||
.I threads | ||
] | ||
[ | ||
.B -S | ||
.I suffix | ||
] | ||
[ | ||
.I "name \&..." | ||
] | ||
.ll -8 | ||
.br | ||
.B unpigz | ||
.RB [ " \-cfhikKlLnNqrRtTz " ] | ||
[ | ||
.B -b | ||
.I blocksize | ||
] | ||
[ | ||
.B -p | ||
.I threads | ||
] | ||
[ | ||
.B -S | ||
.I suffix | ||
] | ||
[ | ||
.I "name \&..." | ||
] | ||
.SH DESCRIPTION | ||
.I Pigz | ||
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 Z_SYNC_FLUSH option of zlib), 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 | ||
.B -b | ||
option. The number of compress threads is set by default to 4, | ||
which can be changed using the | ||
.B -p | ||
option. Specifying | ||
.B -p 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 | ||
.B -i | ||
or | ||
.B --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, | ||
.I pigz | ||
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 | ||
( | ||
.B -dp 1 | ||
or | ||
.B -tp 1 | ||
). | ||
.PP | ||
Compressed files can be restored to their original form using | ||
.I pigz -d | ||
or | ||
.I unpigz. | ||
|
||
.SH OPTIONS | ||
.TP | ||
.B -# --fast --best | ||
Regulate the speed of compression using the specified digit | ||
.IR # , | ||
where | ||
.B \-1 | ||
or | ||
.B \-\-fast | ||
indicates the fastest compression method (less compression) | ||
and | ||
.B \-9 | ||
or | ||
.B \-\-best | ||
indicates the slowest compression method (best compression). | ||
Level 0 is no compression. | ||
.TP | ||
.B -b --blocksize mmm | ||
Set compression block size to mmmK (default 128KiB). | ||
.TP | ||
.B -c --stdout --to-stdout | ||
Write all processed output to stdout (won't delete). | ||
.TP | ||
.B -d --decompress --uncompress | ||
Decompress the compressed input. | ||
.TP | ||
.B -f --force | ||
Force overwrite, compress .gz, links, and to terminal. | ||
.TP | ||
.B -h --help | ||
Display a help screen and quit. | ||
.TP | ||
.B -i --independent | ||
Compress blocks independently for damage recovery. | ||
.TP | ||
.B -k --keep | ||
Do not delete original file after processing. | ||
.TP | ||
.B -K --zip | ||
Compress to PKWare zip (.zip) single entry format. | ||
.TP | ||
.B -l --list | ||
List the contents of the compressed input. | ||
.TP | ||
.B -L --license | ||
Display the | ||
.I pigz | ||
license and quit. | ||
.TP | ||
.B -n --no-name | ||
Do not store or restore file name in/from header. | ||
.TP | ||
.B -N --name | ||
Store/restore file name and mod time in/from header. | ||
.TP | ||
.B -p --processes n | ||
Allow up to n processes (default is the number of online processors) | ||
.TP | ||
.B -q --quiet --silent | ||
Print no messages, even on error. | ||
.TP | ||
.B -r --recursive | ||
Process the contents of all subdirectories. | ||
.TP | ||
.B -S --suffix .sss | ||
Use suffix .sss instead of .gz (for compression). | ||
.TP | ||
.B -t --test | ||
Test the integrity of the compressed input. | ||
.TP | ||
.B -T --no-time | ||
Do not store or restore mod time in/from header. | ||
.TP | ||
.B -v --verbose | ||
Provide more verbose output. | ||
.TP | ||
.B -V --version | ||
Show the version of pigz. | ||
.TP | ||
.B -z --zlib | ||
Compress to zlib (.zz) instead of gzip format. | ||
.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 Mark Adler <madler@alumni.caltech.edu> |
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