programs/lz4.1 - lz4 - Rivoreo Source Code Repositories

 \."
 \." lz4.1: This is a manual page for 'lz4' program. This file is part of the
 \." lz4 <http://www.lz4.org/> project.
 \." Author: Yann Collet
 \."
 .
 \." No hyphenation
 .hy 0
 .nr HY 0
 .
 .TH lz4 "1" "2015-03-21" "lz4" "User Commands"
 .SH NAME
 \fBlz4, unlz4, lz4cat\fR \- Compress or decompress .lz4 files

 .SH SYNOPSIS
 .TP 5
 \fBlz4\fR [\fBOPTIONS\fR] [-|INPUT-FILE] <OUTPUT-FILE>
 .PP
 .B unlz4
 is equivalent to
 .BR "lz4 \-d"
 .br
 .B lz4cat
 is equivalent to
 .BR "lz4 \-dcfm"
 .br
 .PP
 When writing scripts that need to decompress files,
 it is recommended to always use the name
 .B lz4
 with appropriate arguments
 .RB ( "lz4 \-d"
 or
 .BR "lz4 \-dc" )
 instead of the names
 .B unlz4
 and
 .BR lz4cat .


 .SH DESCRIPTION
 .PP
 \fBlz4\fR is an extremely fast lossless compression algorithm,
 based on \fBbyte-aligned LZ77\fR family of compression scheme.
 \fBlz4\fR offers compression speeds of 400 MB/s per core, linearly scalable with multi-core CPUs.
 It features an extremely fast decoder, with speed in multiple GB/s per core,
 typically reaching RAM speed limit on multi-core systems.
 The native file format is the
 .B .lz4
 format.

 .B lz4
 supports a command line syntax similar \fIbut not identical\fR to
 .BR gzip (1).
 Differences are :
  \fBlz4\fR preserves original files
  \fBlz4\fR compresses a single file by default (use \fB-m\fR for multiple files)
  \fBlz4 file1 file2\fR means : compress file1 \fIinto\fR file2
  When no destination name is provided, compressed file name receives a \fB.lz4\fR suffix
  When no destination name is provided, if \fBstdout\fR is \fInot\fR the console, it becomes the output (like a silent \fB-c\fR)
       Therefore \fBlz4 file > /dev/null\fR will not create \fBfile.lz4\fR
  \fBlz4 file\fR shows real-time statistics during compression (use \fB-q\fR to silent them)

 Default behaviors can be modified by opt-in commands, described below.
 \fBlz4 --quiet --multiple\fR more closely mimics \fBgzip\fR behavior.

 .SS "Concatenation of .lz4 files"
 It is possible to concatenate
 .B .lz4
 files as is.
 .B lz4
 will decompress such files as if they were a single
 .B .lz4
 file. For example:
   lz4 file1  > foo.lz4
   lz4 file2 >> foo.lz4
  then
   lz4cat foo.lz4
  is equivalent to :
   cat file1 file2

 .PP

 .SH OPTIONS
 .
 .SS "Short commands concatenation"
 In some cases, some options can be expressed using short command
 .B "-x"
 or long command
 .B "--long-word" .
 Short commands can be concatenated together. For example,
 .B "-d -c"
 is equivalent to
 .B "-dc" .
 Long commands cannot be concatenated.
 They must be clearly separated by a space.
 .SS "Multiple commands"
 When multiple contradictory commands are issued on a same command line,
 only the latest one will be applied.
 .
 .SS "Operation mode"
 .TP
 .BR \-z ", " \-\-compress
 Compress.
 This is the default operation mode
 when no operation mode option is specified ,
 no other operation mode is implied from the command name
 (for example,
 .B unlz4
 implies
 .B \-\-decompress ),
 nor from the input file name
 (for example, a file extension
 .B .lz4
 implies
 .B \-\-decompress
 by default).
 .B -z
 can also be used to force compression of an already compressed
 .B .lz4
 file.
 .TP
 .BR \-d ", " \-\-decompress ", " \-\-uncompress
 Decompress.
 .B --decompress
 is also the default operation when the input filename has an
 .B .lz4
 extension.
 .TP
 .BR \-t ", " \-\-test
 Test the integrity of compressed
 .B .lz4
 files.
 The decompressed data is discarded.
 No files are created nor removed.

 .TP
 .BR \-b#
 Benchmark mode, using # compression level.

 .
 .SS "Operation modifiers"
 .TP
 .B \-#
  compression level, with # being any value from 1 to 16.
  Higher values trade compression speed for compression ratio.
  Values above 16 are considered the same as 16.
  Recommended values are 1 for fast compression (default), and 9 for high compression.
  Speed/compression trade-off will vary depending on data to compress.
  Decompression speed remains fast at all settings.

 .TP
 .BR \-f ", " --[no-]force
  This option has several effects:
 .RS
 .IP \(bu 3
 If the target file already exists,
 overwrite it without prompting.
 .IP \(bu 3
 When used with
 .B \-\-decompress
 and
 .B lz4
 cannot recognize the type of the source file,
 copy the source file as is to standard output.
 This allows
 .B lz4cat
 .B \-\-force
 to be used like
 .BR cat (1)
 for files that have not been compressed with
 .BR lz4 .
 .RE

 .TP
 .BR \-c ", " \--stdout ", " \--to-stdout
  force write to standard output, even if it is the console

 .TP
 .BR \-m ", " \--multiple
  Multiple file names.
  By default, the second filename is used as the destination filename for the compressed file.
  With
 .B -m
 , it is possible to specify any number of input filenames. Each of them will be compressed
 independently, and the resulting name of each compressed file will be
 .B filename.lz4
 .

 .TP
 .B \-B#
  block size [4-7](default : 7)
  B4= 64KB ; B5= 256KB ; B6= 1MB ; B7= 4MB
 .TP
 .B \-BD
  block dependency (improves compression ratio on small blocks)
 .TP
 .B \--[no-]frame-crc
  select frame checksum (default:enabled)
 .TP
 .B \--[no-]content-size
  header includes original size (default:not present)
  Note : this option can only be activated when the original size can be determined,
 hence for a file. It won't work with unknown source size, such as stdin or pipe.
 .TP
 .B \--[no-]sparse
  sparse mode support (default:enabled on file, disabled on stdout)
 .TP
 .B \-l
  use Legacy format (typically used for Linux Kernel compression)
  note : \fB-l\fR is not compatible with \fB-m\fR (\fB--multiple\fR)
 .
 .SS "Other options"
 .TP
 .BR \-v ", " --verbose
  verbose mode
 .TP
 .BR \-q ", " --quiet
  suppress warnings and real-time statistics; specify twice to suppress errors too
 .TP
 .B \-h/\-H ", " --help
  display help/long help and exit
 .TP
 .BR \-V ", " \--version
  display Version number and exit
 .TP
 .BR \-k ", " \--keep
  Don't delete source file.
 This is default behavior anyway, so this option is just for compatibility with gzip/xz.

 .
 .SS "Benchmark mode"
 .TP
 .B \-b#
  benchmark file(s), using # compression level
 .TP
 .B \-e#
  benchmark multiple compression levels, from b# to e# (included)
 .TP
 .B \-i#
  minimum evaluation in seconds [1-9] (default : 3)
 .TP
 .B \-r
  operate recursively on directories


 .SH BUGS
 Report bugs at: https://github.com/Cyan4973/lz4/issues

 .SH AUTHOR
 Yann Collet
	\."
	\." lz4.1: This is a manual page for 'lz4' program. This file is part of the
	\." lz4 <http://www.lz4.org/> project.
	\." Author: Yann Collet
	\."
	.
	\." No hyphenation
	.hy 0
	.nr HY 0
	.
	.TH lz4 "1" "2015-03-21" "lz4" "User Commands"
	.SH NAME
	\fBlz4, unlz4, lz4cat\fR \- Compress or decompress .lz4 files

	.SH SYNOPSIS
	.TP 5
	\fBlz4\fR [\fBOPTIONS\fR] [-\|INPUT-FILE] <OUTPUT-FILE>
	.PP
	.B unlz4
	is equivalent to
	.BR "lz4 \-d"
	.br
	.B lz4cat
	is equivalent to
	.BR "lz4 \-dcfm"
	.br
	.PP
	When writing scripts that need to decompress files,
	it is recommended to always use the name
	.B lz4
	with appropriate arguments
	.RB ( "lz4 \-d"
	or
	.BR "lz4 \-dc" )
	instead of the names
	.B unlz4
	and
	.BR lz4cat .


	.SH DESCRIPTION
	.PP
	\fBlz4\fR is an extremely fast lossless compression algorithm,
	based on \fBbyte-aligned LZ77\fR family of compression scheme.
	\fBlz4\fR offers compression speeds of 400 MB/s per core, linearly scalable with multi-core CPUs.
	It features an extremely fast decoder, with speed in multiple GB/s per core,
	typically reaching RAM speed limit on multi-core systems.
	The native file format is the
	.B .lz4
	format.

	.B lz4
	supports a command line syntax similar \fIbut not identical\fR to
	.BR gzip (1).
	Differences are :
	\fBlz4\fR preserves original files
	\fBlz4\fR compresses a single file by default (use \fB-m\fR for multiple files)
	\fBlz4 file1 file2\fR means : compress file1 \fIinto\fR file2
	When no destination name is provided, compressed file name receives a \fB.lz4\fR suffix
	When no destination name is provided, if \fBstdout\fR is \fInot\fR the console, it becomes the output (like a silent \fB-c\fR)
	Therefore \fBlz4 file > /dev/null\fR will not create \fBfile.lz4\fR
	\fBlz4 file\fR shows real-time statistics during compression (use \fB-q\fR to silent them)

	Default behaviors can be modified by opt-in commands, described below.
	\fBlz4 --quiet --multiple\fR more closely mimics \fBgzip\fR behavior.

	.SS "Concatenation of .lz4 files"
	It is possible to concatenate
	.B .lz4
	files as is.
	.B lz4
	will decompress such files as if they were a single
	.B .lz4
	file. For example:
	lz4 file1 > foo.lz4
	lz4 file2 >> foo.lz4
	then
	lz4cat foo.lz4
	is equivalent to :
	cat file1 file2

	.PP

	.SH OPTIONS
	.
	.SS "Short commands concatenation"
	In some cases, some options can be expressed using short command
	.B "-x"
	or long command
	.B "--long-word" .
	Short commands can be concatenated together. For example,
	.B "-d -c"
	is equivalent to
	.B "-dc" .
	Long commands cannot be concatenated.
	They must be clearly separated by a space.
	.SS "Multiple commands"
	When multiple contradictory commands are issued on a same command line,
	only the latest one will be applied.
	.
	.SS "Operation mode"
	.TP
	.BR \-z ", " \-\-compress
	Compress.
	This is the default operation mode
	when no operation mode option is specified ,
	no other operation mode is implied from the command name
	(for example,
	.B unlz4
	implies
	.B \-\-decompress ),
	nor from the input file name
	(for example, a file extension
	.B .lz4
	implies
	.B \-\-decompress
	by default).
	.B -z
	can also be used to force compression of an already compressed
	.B .lz4
	file.
	.TP
	.BR \-d ", " \-\-decompress ", " \-\-uncompress
	Decompress.
	.B --decompress
	is also the default operation when the input filename has an
	.B .lz4
	extension.
	.TP
	.BR \-t ", " \-\-test
	Test the integrity of compressed
	.B .lz4
	files.
	The decompressed data is discarded.
	No files are created nor removed.

	.TP
	.BR \-b#
	Benchmark mode, using # compression level.

	.
	.SS "Operation modifiers"
	.TP
	.B \-#
	compression level, with # being any value from 1 to 16.
	Higher values trade compression speed for compression ratio.
	Values above 16 are considered the same as 16.
	Recommended values are 1 for fast compression (default), and 9 for high compression.
	Speed/compression trade-off will vary depending on data to compress.
	Decompression speed remains fast at all settings.

	.TP
	.BR \-f ", " --[no-]force
	This option has several effects:
	.RS
	.IP \(bu 3
	If the target file already exists,
	overwrite it without prompting.
	.IP \(bu 3
	When used with
	.B \-\-decompress
	and
	.B lz4
	cannot recognize the type of the source file,
	copy the source file as is to standard output.
	This allows
	.B lz4cat
	.B \-\-force
	to be used like
	.BR cat (1)
	for files that have not been compressed with
	.BR lz4 .
	.RE

	.TP
	.BR \-c ", " \--stdout ", " \--to-stdout
	force write to standard output, even if it is the console

	.TP
	.BR \-m ", " \--multiple
	Multiple file names.
	By default, the second filename is used as the destination filename for the compressed file.
	With
	.B -m
	, it is possible to specify any number of input filenames. Each of them will be compressed
	independently, and the resulting name of each compressed file will be
	.B filename.lz4
	.

	.TP
	.B \-B#
	block size [4-7](default : 7)
	B4= 64KB ; B5= 256KB ; B6= 1MB ; B7= 4MB
	.TP
	.B \-BD
	block dependency (improves compression ratio on small blocks)
	.TP
	.B \--[no-]frame-crc
	select frame checksum (default:enabled)
	.TP
	.B \--[no-]content-size
	header includes original size (default:not present)
	Note : this option can only be activated when the original size can be determined,
	hence for a file. It won't work with unknown source size, such as stdin or pipe.
	.TP
	.B \--[no-]sparse
	sparse mode support (default:enabled on file, disabled on stdout)
	.TP
	.B \-l
	use Legacy format (typically used for Linux Kernel compression)
	note : \fB-l\fR is not compatible with \fB-m\fR (\fB--multiple\fR)
	.
	.SS "Other options"
	.TP
	.BR \-v ", " --verbose
	verbose mode
	.TP
	.BR \-q ", " --quiet
	suppress warnings and real-time statistics; specify twice to suppress errors too
	.TP
	.B \-h/\-H ", " --help
	display help/long help and exit
	.TP
	.BR \-V ", " \--version
	display Version number and exit
	.TP
	.BR \-k ", " \--keep
	Don't delete source file.
	This is default behavior anyway, so this option is just for compatibility with gzip/xz.

	.
	.SS "Benchmark mode"
	.TP
	.B \-b#
	benchmark file(s), using # compression level
	.TP
	.B \-e#
	benchmark multiple compression levels, from b# to e# (included)
	.TP
	.B \-i#
	minimum evaluation in seconds [1-9] (default : 3)
	.TP
	.B \-r
	operate recursively on directories


	.SH BUGS
	Report bugs at: https://github.com/Cyan4973/lz4/issues

	.SH AUTHOR
	Yann Collet