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35 .Nd compression/decompression tool using Lempel-Ziv coding (LZ77)
63 program compresses and decompresses files using Lempel-Ziv coding
69 will compress from standard input, or decompress to standard output.
70 When in compression mode, each
72 will be replaced with another file with the suffix, set by the
74 option, added, if possible.
76 In decompression mode, each
78 will be checked for existence, as will the file with the suffix
82 argument must contain a separate complete archive;
85 are indicated, each is decompressed in turn.
89 the resulting data is then concatenated in the manner of
109 is also capable of decompressing files compressed using
115 The following options are available:
116 .Bl -tag -width XXrXXXrecursiveX
117 .It Fl 1 , Fl Fl fast
118 .It Fl 2 , 3 , 4 , 5 , 6 , 7 , 8
119 .It Fl 9 , Fl Fl best
120 These options change the compression level used, with the
122 option being the fastest, with less compression, and the
124 option being the slowest, with optimal compression.
125 The default compression level is 6.
126 .It Fl c , Fl Fl stdout , Fl Fl to-stdout
127 This option specifies that output will go to the standard output
128 stream, leaving files intact.
129 .It Fl d , Fl Fl decompress , Fl Fl uncompress
130 This option selects decompression rather than compression.
131 .It Fl f , Fl Fl force
132 This option turns on force mode.
133 This allows files with multiple links, symbolic links to regular files,
134 overwriting of pre-existing files, reading from or writing to a terminal,
135 and when combined with the
137 option, allowing non-compressed data to pass through unchanged.
138 .It Fl h , Fl Fl help
139 This option prints a usage summary and exits.
140 .It Fl k , Fl Fl keep
143 from deleting input files after (de)compression.
148 .It Fl l , Fl Fl list
149 This option displays information about the file's compressed and
150 uncompressed size, ratio, uncompressed name.
153 option, it also displays the compression method, CRC, date and time
154 embedded in the file.
155 .It Fl N , Fl Fl name
156 This option causes the stored filename in the input file to be used
158 .It Fl n , Fl Fl no-name
159 This option stops the filename and timestamp from being stored in
161 .It Fl q , Fl Fl quiet
162 With this option, no warnings or errors are printed.
163 .It Fl r , Fl Fl recursive
164 This option is used to
166 the files in a directory tree individually, using the
169 .It Fl S Ar suffix , Fl Fl suffix Ar suffix
170 This option changes the default suffix from .gz to
172 .It Fl t , Fl Fl test
173 This option will test compressed files for integrity.
174 .It Fl V , Fl Fl version
175 This option prints the version of the
178 .It Fl v , Fl Fl verbose
179 This option turns on verbose mode, which prints the compression
180 ratio for each file compressed.
183 If the environment variable
185 is set, it is parsed as a white-space separated list of options
186 handled before any options on the command line.
187 Options on the command line will override anything in
192 utility exits 0 on success,
194 and 2 if a warning occurs.
197 responds to the following signals:
198 .Bl -tag -width indent
200 Report progress to standard error.
211 program was originally written by Jean-loup Gailly, licensed under
212 the GNU Public Licence.
213 Matthew R. Green wrote a simple front end for
215 distribution media, based on the freely re-distributable zlib library.
216 It was enhanced to be mostly feature-compatible with the original
222 This implementation of
224 was ported based on the
228 and first appeared in
232 This implementation of
235 .An Matthew R. Green Aq Mt mrg@eterna.com.au
236 with unpack support written by
237 .An Xin LI Aq Mt delphij@FreeBSD.org .
239 According to RFC 1952, the recorded file size is stored in a 32-bit
240 integer, therefore, it cannot represent files larger than 4GB.
241 This limitation also applies to