1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
\"
\" lz4.1: This is a manual page for 'lz4' program. This file is part of the
\" lz4 <https://code.google.com/p/lz4/> 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 \-dc"
.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.
.B lz4
supports a command line syntax similar to
.BR gzip (1).
The native file format is the
.B .lz4
format.
.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.
.PP
.SH OPTIONS
.
.SS "Short command 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 "Operation mode"
If multiple operation mode options are given,
the last one takes effect.
.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
extensionq
.TP
.BR \-t ", " \-\-test
Test the integrity of compressed
.B .lz4
files.
The decompressed data is discarded.
No files are created or removed.
.
.SS "Operation modifiers"
.TP
.B \-1
fast compression (default)
.TP
.B \-9
high compression
.TP
.BR \-f ", " --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 file names.
By default, the second filename is used as the output filename for the compressed file.
With
.B -m
, you can specify any number of input filenames, each of them will be compressed
with the resulting compressed file named
.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 (improve compression ratio)
.TP
.B \--no-frame-crc
disable stream checksum (default:enabled)
.TP
.B \--frame-content-size
compressed frame includes original size (default:not present)
.TP
.B \--sparse-support
enable sparse file (default:disabled)(experimental)
.TP
.B \-l
use Legacy format (useful for Linux Kernel compression)
.
.SS "Other options"
.TP
.BR \-v ", " --verbose
verbose mode
.TP
.BR \-q ", " --quiet
suppress warnings; specify twice to suppress errors too
.TP
.B \-h/\-H
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.
.TP
.B \-b
benchmark file(s)
.TP
.B \-i#
iteration loops [1-9](default : 3), benchmark mode only
.SH BUGS
Report bugs at: https://github.com/Cyan4973/lz4
.SH AUTHOR
Yann Collet
|