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3 .\" Copyright (c) 1997, 2003, 2004 Matthew R. Green
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33 .Nd compression/decompression tool using Lempel-Ziv coding (LZ77)
61 program compresses and decompresses files using Lempel-Ziv coding
67 will compress from standard input, or decompress to standard output.
68 When in compression mode, each
70 will be replaced with another file with the suffix, set by the
72 option, added, if possible.
74 In decompression mode, each
76 will be checked for existence, as will the file with the suffix
80 argument must contain a separate complete archive;
83 are indicated, each is decompressed in turn.
87 the resulting data is then concatenated in the manner of
107 is also capable of decompressing files compressed using
112 The following options are available:
113 .Bl -tag -width XXrXXXrecursiveX
115 .It Fl 2 , 3 , 4 , 5 , 6 , 7 , 8
117 These options change the compression level used, with the
119 option being the fastest, with less compression, and the
121 option being the slowest, with optimal compression.
122 The default compression level is 6.
123 .It Fl c , -stdout , -to-stdout
124 This option specifies that output will go to the standard output
125 stream, leaving files intact.
126 .It Fl d , -decompress , -uncompress
127 This option selects decompression rather than compression.
129 This option turns on force mode.
130 This allows files with multiple links, overwriting of pre-existing
131 files, reading from or writing to a terminal, and when combined
134 option, allowing non-compressed data to pass through unchanged.
136 This option prints a usage summary and exits.
138 Keep (don't delete) input files during compression
145 This option displays information about the file's compressed and
146 uncompressed size, ratio, uncompressed name.
149 option, it also displays the compression method, CRC, date and time
150 embedded in the file.
152 This option causes the stored filename in the input file to be used
155 This option stops the filename and timestamp from being stored in
158 With this option, no warnings or errors are printed.
159 .It Fl r , -recursive
160 This option is used to
162 the files in a directory tree individually, using the
165 .It Fl S Ar suffix , Fl -suffix Ar suffix
166 This option changes the default suffix from .gz to
169 This option will test compressed files for integrity.
171 This option prints the version of the
175 This option turns on verbose mode, which prints the compression
176 ratio for each file compressed.
179 If the environment variable
181 is set, it is parsed as a white-space separated list of options
182 handled before any options on the command line.
183 Options on the command line will override anything in
193 program was originally written by Jean-loup Gailly, licensed under
194 the GNU Public Licence.
195 Matthew R. Green wrote a simple front end for
197 distribution media, based on the freely re-distributable zlib library.
198 It was enhanced to be mostly feature-compatible with the original
204 This implementation of
206 was ported based on the
209 and first appeared in
213 This implementation of
216 .An Matthew R. Green Aq mrg@eterna.com.au
217 with unpack support written by
218 .An Xin LI Aq delphij@FreeBSD.org .
220 According to RFC 1952, the recorded file size is stored in a 32-bit
221 integer, therefore, it can not represent files larger than 4GB.
222 This limitation also applies to