programs/lz4.1 - platform/external/lz4 - Git at Google

 .
 .TH "LZ4" "1" "November 2016" "lz4 1.7.4" "User Commands"
 .
 .SH "NAME"
 \fBlz4\fR \- lz4, unlz4, lz4cat \- Compress or decompress \.lz4 files
 .
 .SH "SYNOPSIS"
 \fBlz4\fR [\fIOPTIONS\fR] [\-|INPUT\-FILE] \fIOUTPUT\-FILE\fR
 .
 .P
 \fBunlz4\fR is equivalent to \fBlz4 \-d\fR
 .
 .P
 \fBlz4cat\fR is equivalent to \fBlz4 \-dcfm\fR
 .
 .P
 When writing scripts that need to decompress files, it is recommended to always use the name \fBlz4\fR with appropriate arguments (\fBlz4 \-d\fR or \fBlz4 \-dc\fR) instead of the names \fBunlz4\fR and \fBlz4cat\fR\.
 .
 .SH "DESCRIPTION"
 \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 \fB\.lz4\fR format\.
 .
 .SS "Difference between lz4 and gzip"
 \fBlz4\fR supports a command line syntax similar \fIbut not identical\fR to \fBgzip(1)\fR\. Differences are :
 .
 .IP "\(bu" 4
 \fBlz4\fR preserves original files
 .
 .IP "\(bu" 4
 \fBlz4\fR compresses a single file by default (see \fB\-m\fR for multiple files)
 .
 .IP "\(bu" 4
 \fBlz4 file1 file2\fR means : compress file1 \fIinto\fR file2
 .
 .IP "\(bu" 4
 \fBlz4\fR shows real\-time notification statistics during compression or decompression of a single file (use \fB\-q\fR to silent them)
 .
 .IP "\(bu" 4
 If no destination name is provided, result is sent to \fBstdout\fR \fIexcept if stdout is the console\fR\.
 .
 .IP "\(bu" 4
 If no destination name is provided, \fBand\fR if \fBstdout\fR is the console, \fBfile\fR is compressed into \fBfile\.lz4\fR\.
 .
 .IP "\(bu" 4
 As a consequence of previous rules, note the following example : \fBlz4 file | consumer\fR sends compressed data to \fBconsumer\fR through \fBstdout\fR, hence it does \fInot\fR create any \fBfile\.lz4\fR\.
 .
 .IP "" 0
 .
 .P
 Default behaviors can be modified by opt\-in commands, detailed below\.
 .
 .IP "\(bu" 4
 \fBlz4 \-m\fR makes it possible to provide multiple input filenames, which will be compressed into files using suffix \fB\.lz4\fR\. Progress notifications are also disabled by default\. This mode has a behavior which more closely mimics \fBgzip\fR command line, with the main difference being that source files are preserved by default\.
 .
 .IP "\(bu" 4
 It\'s possible to opt\-in to erase source files on successful compression or decompression, using \fB\-\-rm\fR command\.
 .
 .IP "\(bu" 4
 Consequently, \fBlz4 \-m \-\-rm\fR behaves the same as \fBgzip\fR\.
 .
 .IP "" 0
 .
 .SS "Concatenation of \.lz4 files"
 It is possible to concatenate \fB\.lz4\fR files as is\. \fBlz4\fR will decompress such files as if they were a single \fB\.lz4\fR file\. For example: lz4 file1 > foo\.lz4 lz4 file2 >> foo\.lz4
 .
 .P
 then lz4cat foo\.lz4
 .
 .P
 is equivalent to : cat file1 file2
 .
 .SH "OPTIONS"
 .
 .SS "Short commands concatenation"
 In some cases, some options can be expressed using short command \fB\-x\fR or long command \fB\-\-long\-word\fR\. Short commands can be concatenated together\. For example, \fB\-d \-c\fR is equivalent to \fB\-dc\fR\. 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
 \fB\-z\fR \fB\-\-compress\fR
 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, \fBunlz4\fR implies \fB\-\-decompress\fR), nor from the input file name (for example, a file extension \fB\.lz4\fR implies \fB\-\-decompress\fR by default)\. \fB\-z\fR can also be used to force compression of an already compressed \fB\.lz4\fR file\.
 .
 .TP
 \fB\-d\fR \fB\-\-decompress\fR \fB\-\-uncompress\fR
 Decompress\. \fB\-\-decompress\fR is also the default operation when the input filename has an \fB\.lz4\fR extension\.
 .
 .TP
 \fB\-t\fR \fB\-\-test\fR
 Test the integrity of compressed \fB\.lz4\fR files\. The decompressed data is discarded\. No files are created nor removed\.
 .
 .TP
 \fB\-b#\fR
 Benchmark mode, using \fB#\fR compression level\.
 .
 .SS "Operation modifiers"
 .
 .TP
 \fB\-#\fR
 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
 \fB\-f\fR \fB\-\-[no\-]force\fR
 This option has several effects:
 .
 .IP
 If the target file already exists, overwrite it without prompting\.
 .
 .IP
 When used with \fB\-\-decompress\fR and \fBlz4\fR cannot recognize the type of the source file, copy the source file as is to standard output\. This allows \fBlz4cat \-\-force\fR to be used like \fBcat (1)\fR for files that have not been compressed with \fBlz4\fR\.
 .
 .TP
 \fB\-c\fR \fB\-\-stdout\fR \fB\-\-to\-stdout\fR
 Force write to standard output, even if it is the console\.
 .
 .TP
 \fB\-m\fR \fB\-\-multiple\fR
 Multiple input files\. Compressed file names will be appended a \fB\.lz4\fR suffix\. This mode also reduces notification level\. \fBlz4 \-m\fR has a behavior equivalent to \fBgzip \-k\fR (it preserves source files by default)\.
 .
 .TP
 \fB\-r\fR
 operate recursively on directories\. This mode also sets \fB\-m\fR (multiple input files)\.
 .
 .TP
 \fB\-B#\fR
 Block size [4\-7](default : 7)
 .
 .br
 \fB\-B4\fR= 64KB ; \fB\-B5\fR= 256KB ; \fB\-B6\fR= 1MB ; \fB\-B7\fR= 4MB
 .
 .TP
 \fB\-BD\fR
 Block Dependency (improves compression ratio on small blocks)
 .
 .TP
 \fB\-\-[no\-]frame\-crc\fR
 Select frame checksum (default:enabled)
 .
 .TP
 \fB\-\-[no\-]content\-size\fR
 Header includes original size (default:not present)
 .
 .br
 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
 \fB\-\-[no\-]sparse\fR
 Sparse mode support (default:enabled on file, disabled on stdout)
 .
 .TP
 \fB\-l\fR
 Use Legacy format (typically for Linux Kernel compression)
 .
 .br
 Note : \fB\-l\fR is not compatible with \fB\-m\fR (\fB\-\-multiple\fR) nor \fB\-r\fR
 .
 .SS "Other options"
 .
 .TP
 \fB\-v\fR \fB\-\-verbose\fR
 Verbose mode
 .
 .TP
 \fB\-q\fR \fB\-\-quiet\fR
 Suppress warnings and real\-time statistics; specify twice to suppress errors too
 .
 .TP
 \fB\-h\fR \fB\-H\fR \fB\-\-help\fR
 Display help/long help and exit
 .
 .TP
 \fB\-V\fR \fB\-\-version\fR
 Display Version number and exit
 .
 .TP
 \fB\-k\fR \fB\-\-keep\fR
 Preserve source files (default behavior)
 .
 .TP
 \fB\-\-rm\fR
 Delete source files on successful compression or decompression
 .
 .SS "Benchmark mode"
 .
 .TP
 \fB\-b#\fR
 Benchmark file(s), using # compression level
 .
 .TP
 \fB\-e#\fR
 Benchmark multiple compression levels, from b# to e# (included)
 .
 .TP
 \fB\-i#\fR
 Minimum evaluation in seconds [1\-9] (default : 3)
 .
 .TP
 \fB\-r\fR
 Operate recursively on directories
 .
 .SH "BUGS"
 Report bugs at: https://github\.com/lz4/lz4/issues
 .
 .SH "AUTHOR"
 Yann Collet
	.
	.TH "LZ4" "1" "November 2016" "lz4 1.7.4" "User Commands"
	.
	.SH "NAME"
	\fBlz4\fR \- lz4, unlz4, lz4cat \- Compress or decompress \.lz4 files
	.
	.SH "SYNOPSIS"
	\fBlz4\fR [\fIOPTIONS\fR] [\-\|INPUT\-FILE] \fIOUTPUT\-FILE\fR
	.
	.P
	\fBunlz4\fR is equivalent to \fBlz4 \-d\fR
	.
	.P
	\fBlz4cat\fR is equivalent to \fBlz4 \-dcfm\fR
	.
	.P
	When writing scripts that need to decompress files, it is recommended to always use the name \fBlz4\fR with appropriate arguments (\fBlz4 \-d\fR or \fBlz4 \-dc\fR) instead of the names \fBunlz4\fR and \fBlz4cat\fR\.
	.
	.SH "DESCRIPTION"
	\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 \fB\.lz4\fR format\.
	.
	.SS "Difference between lz4 and gzip"
	\fBlz4\fR supports a command line syntax similar \fIbut not identical\fR to \fBgzip(1)\fR\. Differences are :
	.
	.IP "\(bu" 4
	\fBlz4\fR preserves original files
	.
	.IP "\(bu" 4
	\fBlz4\fR compresses a single file by default (see \fB\-m\fR for multiple files)
	.
	.IP "\(bu" 4
	\fBlz4 file1 file2\fR means : compress file1 \fIinto\fR file2
	.
	.IP "\(bu" 4
	\fBlz4\fR shows real\-time notification statistics during compression or decompression of a single file (use \fB\-q\fR to silent them)
	.
	.IP "\(bu" 4
	If no destination name is provided, result is sent to \fBstdout\fR \fIexcept if stdout is the console\fR\.
	.
	.IP "\(bu" 4
	If no destination name is provided, \fBand\fR if \fBstdout\fR is the console, \fBfile\fR is compressed into \fBfile\.lz4\fR\.
	.
	.IP "\(bu" 4
	As a consequence of previous rules, note the following example : \fBlz4 file \| consumer\fR sends compressed data to \fBconsumer\fR through \fBstdout\fR, hence it does \fInot\fR create any \fBfile\.lz4\fR\.
	.
	.IP "" 0
	.
	.P
	Default behaviors can be modified by opt\-in commands, detailed below\.
	.
	.IP "\(bu" 4
	\fBlz4 \-m\fR makes it possible to provide multiple input filenames, which will be compressed into files using suffix \fB\.lz4\fR\. Progress notifications are also disabled by default\. This mode has a behavior which more closely mimics \fBgzip\fR command line, with the main difference being that source files are preserved by default\.
	.
	.IP "\(bu" 4
	It\'s possible to opt\-in to erase source files on successful compression or decompression, using \fB\-\-rm\fR command\.
	.
	.IP "\(bu" 4
	Consequently, \fBlz4 \-m \-\-rm\fR behaves the same as \fBgzip\fR\.
	.
	.IP "" 0
	.
	.SS "Concatenation of \.lz4 files"
	It is possible to concatenate \fB\.lz4\fR files as is\. \fBlz4\fR will decompress such files as if they were a single \fB\.lz4\fR file\. For example: lz4 file1 > foo\.lz4 lz4 file2 >> foo\.lz4
	.
	.P
	then lz4cat foo\.lz4
	.
	.P
	is equivalent to : cat file1 file2
	.
	.SH "OPTIONS"
	.
	.SS "Short commands concatenation"
	In some cases, some options can be expressed using short command \fB\-x\fR or long command \fB\-\-long\-word\fR\. Short commands can be concatenated together\. For example, \fB\-d \-c\fR is equivalent to \fB\-dc\fR\. 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
	\fB\-z\fR \fB\-\-compress\fR
	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, \fBunlz4\fR implies \fB\-\-decompress\fR), nor from the input file name (for example, a file extension \fB\.lz4\fR implies \fB\-\-decompress\fR by default)\. \fB\-z\fR can also be used to force compression of an already compressed \fB\.lz4\fR file\.
	.
	.TP
	\fB\-d\fR \fB\-\-decompress\fR \fB\-\-uncompress\fR
	Decompress\. \fB\-\-decompress\fR is also the default operation when the input filename has an \fB\.lz4\fR extension\.
	.
	.TP
	\fB\-t\fR \fB\-\-test\fR
	Test the integrity of compressed \fB\.lz4\fR files\. The decompressed data is discarded\. No files are created nor removed\.
	.
	.TP
	\fB\-b#\fR
	Benchmark mode, using \fB#\fR compression level\.
	.
	.SS "Operation modifiers"
	.
	.TP
	\fB\-#\fR
	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
	\fB\-f\fR \fB\-\-[no\-]force\fR
	This option has several effects:
	.
	.IP
	If the target file already exists, overwrite it without prompting\.
	.
	.IP
	When used with \fB\-\-decompress\fR and \fBlz4\fR cannot recognize the type of the source file, copy the source file as is to standard output\. This allows \fBlz4cat \-\-force\fR to be used like \fBcat (1)\fR for files that have not been compressed with \fBlz4\fR\.
	.
	.TP
	\fB\-c\fR \fB\-\-stdout\fR \fB\-\-to\-stdout\fR
	Force write to standard output, even if it is the console\.
	.
	.TP
	\fB\-m\fR \fB\-\-multiple\fR
	Multiple input files\. Compressed file names will be appended a \fB\.lz4\fR suffix\. This mode also reduces notification level\. \fBlz4 \-m\fR has a behavior equivalent to \fBgzip \-k\fR (it preserves source files by default)\.
	.
	.TP
	\fB\-r\fR
	operate recursively on directories\. This mode also sets \fB\-m\fR (multiple input files)\.
	.
	.TP
	\fB\-B#\fR
	Block size [4\-7](default : 7)
	.
	.br
	\fB\-B4\fR= 64KB ; \fB\-B5\fR= 256KB ; \fB\-B6\fR= 1MB ; \fB\-B7\fR= 4MB
	.
	.TP
	\fB\-BD\fR
	Block Dependency (improves compression ratio on small blocks)
	.
	.TP
	\fB\-\-[no\-]frame\-crc\fR
	Select frame checksum (default:enabled)
	.
	.TP
	\fB\-\-[no\-]content\-size\fR
	Header includes original size (default:not present)
	.
	.br
	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
	\fB\-\-[no\-]sparse\fR
	Sparse mode support (default:enabled on file, disabled on stdout)
	.
	.TP
	\fB\-l\fR
	Use Legacy format (typically for Linux Kernel compression)
	.
	.br
	Note : \fB\-l\fR is not compatible with \fB\-m\fR (\fB\-\-multiple\fR) nor \fB\-r\fR
	.
	.SS "Other options"
	.
	.TP
	\fB\-v\fR \fB\-\-verbose\fR
	Verbose mode
	.
	.TP
	\fB\-q\fR \fB\-\-quiet\fR
	Suppress warnings and real\-time statistics; specify twice to suppress errors too
	.
	.TP
	\fB\-h\fR \fB\-H\fR \fB\-\-help\fR
	Display help/long help and exit
	.
	.TP
	\fB\-V\fR \fB\-\-version\fR
	Display Version number and exit
	.
	.TP
	\fB\-k\fR \fB\-\-keep\fR
	Preserve source files (default behavior)
	.
	.TP
	\fB\-\-rm\fR
	Delete source files on successful compression or decompression
	.
	.SS "Benchmark mode"
	.
	.TP
	\fB\-b#\fR
	Benchmark file(s), using # compression level
	.
	.TP
	\fB\-e#\fR
	Benchmark multiple compression levels, from b# to e# (included)
	.
	.TP
	\fB\-i#\fR
	Minimum evaluation in seconds [1\-9] (default : 3)
	.
	.TP
	\fB\-r\fR
	Operate recursively on directories
	.
	.SH "BUGS"
	Report bugs at: https://github\.com/lz4/lz4/issues
	.
	.SH "AUTHOR"
	Yann Collet