gzip/gzip.1

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   3 .\" Copyright (c) 1997, 2003, 2004 Matthew R. Green
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  27 .\" $FreeBSD: src/usr.bin/gzip/gzip.1,v 1.11 2011/10/10 06:37:32 delphij Exp $
  28 .Dd October 9, 2011
  29 .Dt GZIP 1
  30 .Os
  31 .Sh NAME
  32 .Nm gzip
  33 .Nd compression/decompression tool using Lempel-Ziv coding (LZ77)
  34 .Sh SYNOPSIS
  35 .Nm
  36 .Op Fl cdfhkLlNnqrtVv
  37 .Op Fl S Ar suffix
  38 .Ar file
  39 .Oo
  40 .Ar file Oo ...
  41 .Oc
  42 .Oc
  43 .Nm gunzip
  44 .Op Fl cfhkLNqrtVv
  45 .Op Fl S Ar suffix
  46 .Ar file
  47 .Oo
  48 .Ar file Oo ...
  49 .Oc
  50 .Oc
  51 .Nm zcat
  52 .Op Fl fhV
  53 .Ar file
  54 .Oo
  55 .Ar file Oo ...
  56 .Oc
  57 .Oc
  58 .Sh DESCRIPTION
  59 The
  60 .Nm
  61 program compresses and decompresses files using Lempel-Ziv coding
  62 (LZ77).
  63 If no
  64 .Ar files
  65 are specified,
  66 .Nm
  67 will compress from standard input, or decompress to standard output.
  68 When in compression mode, each
  69 .Ar file
  70 will be replaced with another file with the suffix, set by the
  71 .Fl S Ar suffix
  72 option, added, if possible.
  73 .Pp
  74 In decompression mode, each
  75 .Ar file
  76 will be checked for existence, as will the file with the suffix
  77 added.
  78 Each
  79 .Ar file
  80 argument must contain a separate complete archive;
  81 when multiple
  82 .Ar files
  83 are indicated, each is decompressed in turn.
  84 .Pp
  85 In the case of
  86 .Nm gzcat
  87 the resulting data is then concatenated in the manner of
  88 .Xr cat 1 .
  89 .Pp
  90 If invoked as
  91 .Nm gunzip
  92 then the
  93 .Fl d
  94 option is enabled.
  95 If invoked as
  96 .Nm zcat
  97 or
  98 .Nm gzcat
  99 then both the
 100 .Fl c
 101 and
 102 .Fl d
 103 options are enabled.
 104 When invoked as
 105 .Nm zcat ,
 106 .Dq .Z
 107 will be appended to all filenames that do not have that suffix.
 108 .Pp
 109 This version of
 110 .Nm
 111 is also capable of decompressing files compressed using
 112 .Xr compress 1
 113 or
 114 .Xr bzip2 1 .
 115 .Sh OPTIONS
 116 The following options are available:
 117 .Bl -tag -width XXrXXXrecursiveX
 118 .It Fl 1 , -fast
 119 .It Fl 2 , 3 , 4 , 5 , 6 , 7 , 8
 120 .It Fl 9 , -best
 121 These options change the compression level used, with the
 122 .Fl 1
 123 option being the fastest, with less compression, and the
 124 .Fl 9
 125 option being the slowest, with optimal compression.
 126 The default compression level is 6.
 127 .It Fl c , -stdout , -to-stdout
 128 This option specifies that output will go to the standard output
 129 stream, leaving files intact.
 130 .It Fl d , -decompress , -uncompress
 131 This option selects decompression rather than compression.
 132 .It Fl f , -force
 133 This option turns on force mode.
 134 This allows files with multiple links, symbolic links to regular files,
 135 overwriting of pre-existing files, reading from or writing to a terminal,
 136 and when combined with the
 137 .Fl c
 138 option, allowing non-compressed data to pass through unchanged.
 139 .It Fl h , -help
 140 This option prints a usage summary and exits.
 141 .It Fl k , -keep
 142 Keep (don't delete) input files during compression
 143 or decompression.
 144 .It Fl L , -license
 145 This option prints
 146 .Nm
 147 license.
 148 .It Fl l , -list
 149 This option displays information about the file's compressed and
 150 uncompressed size, ratio, uncompressed name.
 151 With the
 152 .Fl v
 153 option, it also displays the compression method, CRC, date and time
 154 embedded in the file.
 155 .It Fl N , -name
 156 This option causes the stored filename in the input file to be used
 157 as the output file.
 158 .It Fl n , -no-name
 159 This option stops the filename and timestamp from being stored in
 160 the output file.
 161 .It Fl q , -quiet
 162 With this option, no warnings or errors are printed.
 163 .It Fl r , -recursive
 164 This option is used to
 165 .Nm
 166 the files in a directory tree individually, using the
 167 .Xr fts 3
 168 library.
 169 .It Fl S Ar suffix , Fl -suffix Ar suffix
 170 This option changes the default suffix from .gz to
 171 .Ar suffix .
 172 .It Fl t , -test
 173 This option will test compressed files for integrity.
 174 .It Fl V , -version
 175 This option prints the version of the
 176 .Nm
 177 program.
 178 .It Fl v , -verbose
 179 This option turns on verbose mode, which prints the compression
 180 ratio for each file compressed.
 181 .El
 182 .Sh ENVIRONMENT
 183 If the environment variable
 184 .Ev GZIP
 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
 188 .Ev GZIP .
 189 .Sh SEE ALSO
 190 .Xr bzip2 1 ,
 191 .Xr compress 1 ,
 192 .Xr xz 1 ,
 193 .Xr fts 3 ,
 194 .Xr zlib 3 ,
 195 .Xr compat 5
 196 .Sh HISTORY
 197 The
 198 .Nm
 199 program was originally written by Jean-loup Gailly, licensed under
 200 the GNU Public Licence.
 201 Matthew R. Green wrote a simple front end for
 202 .Nx 1.3
 203 distribution media, based on the freely re-distributable zlib library.
 204 It was enhanced to be mostly feature-compatible with the original
 205 GNU
 206 .Nm
 207 program for
 208 .Nx 2.0 .
 209 .Pp
 210 This implementation of
 211 .Nm
 212 was ported based on the
 213 .Nx
 214 .Nm ,
 215 and first appeared in
 216 .Fx 7.0 .
 217 .Sh AUTHORS
 218 .An -nosplit
 219 This implementation of
 220 .Nm
 221 was written by
 222 .An Matthew R. Green Aq mrg@eterna.com.au
 223 with unpack support written by
 224 .An Xin LI Aq delphij@FreeBSD.org .
 225 .Sh BUGS
 226 According to RFC 1952, the recorded file size is stored in a 32-bit
 227 integer, therefore, it can not represent files larger than 4GB.
 228 This limitation also applies to
 229 .Fl l
 230 option of
 231 .Nm
 232 utility.