pigz.1 - third_party/github.com/madler/pigz - Git at Google

 .TH PIGZ 1 "February 6, 2021"
 .SH NAME
 pigz, unpigz \- compress or expand files
 .SH SYNOPSIS
 .ll +8
 .B pigz
 .RB [ " \-cdfhikKlLmMnNqrRtz0..9,11 " ]
 [
 .B -b
 .I blocksize
 ]
 [
 .B -p
 .I threads
 ]
 [
 .B -S
 .I suffix
 ]
 [
 .I "name \&..."
 ]
 .ll -8
 .br
 .B unpigz
 .RB [ " \-cfhikKlLmMnNqrRtz " ]
 [
 .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 the number
 of online processors,
 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. This also
 inserts an extra empty block to flag independent blocks by prefacing
 each with the nine-byte sequence (in hex): 00 00 FF FF 00 00 00 FF FF.
 .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
 All options on the command line are processed before any names are processed.
 If no names are provided on the command line, or if "-" is given as a name (but
 not after "--"), then the input is taken from stdin.
 .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).
 .B -0
 is no compression.
 .B \-11
 gives a few percent better compression at a severe cost in execution time,
 using the zopfli algorithm by Jyrki Alakuijala.
 The default is
 .B \-6.
 .TP
 .B -A --alias xxx
 Use xxx as the name for any --zip entry from stdin (the default name is "-").
 .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 -C --comment ccc
 Include the provided comment in the gzip header or zip central file header.
 .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 -H --huffman
 Compress using the Huffman-only strategy.
 .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 -m --no-time
 Do not store or restore the modification time. -Nm will store or restore the
 name, but not the modification time. Note that the order of the options is
 important.
 .TP
 .B -M --time
 Store or restore the modification time. -nM will store or restore the
 modification time, but not the name. Note that the order of the options is
 important.
 .TP
 .B -n --no-name
 Do not store or restore the file name or the modification time. This is the
 default when decompressing. When the file name is not restored from the header,
 the name of the compressed file with the suffix stripped is the name of the
 decompressed file. When the modification time is not restored from the header,
 the modification time of the compressed file is used (not the current time).
 .TP
 .B -N --name
 Store or restore both the file name and the modification time. This is the
 default when compressing.
 .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 -R --rsyncable
 Input-determined block locations for rsync.
 .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 -U --rle
 Compress using the run length encoding strategy.
 .TP
 .B -v --verbose
 Provide more verbose output.
 .TP
 .B -V --version
 Show the version of pigz. -vV also shows the zlib version.
 .TP
 .B -z --zlib
 Compress to zlib (.zz) instead of gzip format.
 .TP
 .B --
 All arguments after "--" are treated as file names (for names that start with "-")
 .TP
 These options are unique to the -11 compression level:
 .TP
 .B -F  --first
 Do iterations first, before block split (default is last).
 .TP
 .B -I, --iterations n
 Number of iterations for optimization (default 15).
 .TP
 .B -J, --maxsplits n
 Maximum number of split blocks (default 15).
 .TP
 .B -O  --oneblock
 Do not split into smaller blocks (default is block splitting).
 .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) 2007-2021 Mark Adler <madler@alumni.caltech.edu>
	.TH PIGZ 1 "February 6, 2021"
	.SH NAME
	pigz, unpigz \- compress or expand files
	.SH SYNOPSIS
	.ll +8
	.B pigz
	.RB [ " \-cdfhikKlLmMnNqrRtz0..9,11 " ]
	[
	.B -b
	.I blocksize
	]
	[
	.B -p
	.I threads
	]
	[
	.B -S
	.I suffix
	]
	[
	.I "name \&..."
	]
	.ll -8
	.br
	.B unpigz
	.RB [ " \-cfhikKlLmMnNqrRtz " ]
	[
	.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 the number
	of online processors,
	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. This also
	inserts an extra empty block to flag independent blocks by prefacing
	each with the nine-byte sequence (in hex): 00 00 FF FF 00 00 00 FF FF.
	.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
	All options on the command line are processed before any names are processed.
	If no names are provided on the command line, or if "-" is given as a name (but
	not after "--"), then the input is taken from stdin.
	.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).
	.B -0
	is no compression.
	.B \-11
	gives a few percent better compression at a severe cost in execution time,
	using the zopfli algorithm by Jyrki Alakuijala.
	The default is
	.B \-6.
	.TP
	.B -A --alias xxx
	Use xxx as the name for any --zip entry from stdin (the default name is "-").
	.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 -C --comment ccc
	Include the provided comment in the gzip header or zip central file header.
	.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 -H --huffman
	Compress using the Huffman-only strategy.
	.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 -m --no-time
	Do not store or restore the modification time. -Nm will store or restore the
	name, but not the modification time. Note that the order of the options is
	important.
	.TP
	.B -M --time
	Store or restore the modification time. -nM will store or restore the
	modification time, but not the name. Note that the order of the options is
	important.
	.TP
	.B -n --no-name
	Do not store or restore the file name or the modification time. This is the
	default when decompressing. When the file name is not restored from the header,
	the name of the compressed file with the suffix stripped is the name of the
	decompressed file. When the modification time is not restored from the header,
	the modification time of the compressed file is used (not the current time).
	.TP
	.B -N --name
	Store or restore both the file name and the modification time. This is the
	default when compressing.
	.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 -R --rsyncable
	Input-determined block locations for rsync.
	.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 -U --rle
	Compress using the run length encoding strategy.
	.TP
	.B -v --verbose
	Provide more verbose output.
	.TP
	.B -V --version
	Show the version of pigz. -vV also shows the zlib version.
	.TP
	.B -z --zlib
	Compress to zlib (.zz) instead of gzip format.
	.TP
	.B --
	All arguments after "--" are treated as file names (for names that start with "-")
	.TP
	These options are unique to the -11 compression level:
	.TP
	.B -F --first
	Do iterations first, before block split (default is last).
	.TP
	.B -I, --iterations n
	Number of iterations for optimization (default 15).
	.TP
	.B -J, --maxsplits n
	Maximum number of split blocks (default 15).
	.TP
	.B -O --oneblock
	Do not split into smaller blocks (default is block splitting).
	.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) 2007-2021 Mark Adler <madler@alumni.caltech.edu>