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27 .\" $FreeBSD: head/usr.bin/gzip/gzip.1 290073 2015-10-27 21:26:05Z delphij $

28 .Dd October 26, 2015

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 .Pp

105 This version of

106 .Nm

107 is also capable of decompressing files compressed using

108 .Xr compress 1 ,

109 .Xr bzip2 1 ,

110 or

111 .Xr xz 1 .

112 .Sh OPTIONS

113 The following options are available:

114 .Bl -tag -width XXrXXXrecursiveX

115 .It Fl 1 , -fast

116 .It Fl 2 , 3 , 4 , 5 , 6 , 7 , 8

117 .It Fl 9 , -best

118 These options change the compression level used, with the

119 .Fl 1

120 option being the fastest, with less compression, and the

121 .Fl 9

122 option being the slowest, with optimal compression.

123 The default compression level is 6.

124 .It Fl c , -stdout , -to-stdout

125 This option specifies that output will go to the standard output

126 stream, leaving files intact.

127 .It Fl d , -decompress , -uncompress

128 This option selects decompression rather than compression.

129 .It Fl f , -force

130 This option turns on force mode.

131 This allows files with multiple links, symbolic links to regular files,

132 overwriting of pre-existing files, reading from or writing to a terminal,

133 and when combined with the

134 .Fl c

135 option, allowing non-compressed data to pass through unchanged.

136 .It Fl h , -help

137 This option prints a usage summary and exits.

138 .It Fl k , -keep

139 Keep (do not delete) input files during compression

140 or decompression.

141 .It Fl L , -license

142 This option prints

143 .Nm

144 license.

145 .It Fl l , -list

146 This option displays information about the file's compressed and

147 uncompressed size, ratio, uncompressed name.

148 With the

149 .Fl v

150 option, it also displays the compression method, CRC, date and time

151 embedded in the file.

152 .It Fl N , -name

153 This option causes the stored filename in the input file to be used

154 as the output file.

155 .It Fl n , -no-name

156 This option stops the filename and timestamp from being stored in

157 the output file.

158 .It Fl q , -quiet

159 With this option, no warnings or errors are printed.

160 .It Fl r , -recursive

161 This option is used to

162 .Nm

163 the files in a directory tree individually, using the

164 .Xr fts 3

165 library.

166 .It Fl S Ar suffix , Fl -suffix Ar suffix

167 This option changes the default suffix from .gz to

168 .Ar suffix .

169 .It Fl t , -test

170 This option will test compressed files for integrity.

171 .It Fl V , -version

172 This option prints the version of the

173 .Nm

174 program.

175 .It Fl v , -verbose

176 This option turns on verbose mode, which prints the compression

177 ratio for each file compressed.

178 .El

179 .Sh ENVIRONMENT

180 If the environment variable

181 .Ev GZIP

182 is set, it is parsed as a white-space separated list of options

183 handled before any options on the command line.

184 Options on the command line will override anything in

185 .Ev GZIP .

186 .Sh EXIT STATUS

187 The

188 .Nm

189 utility exits 0 on success,

190 1 on errors,

191 and 2 if a warning occurs.

192 .Sh SEE ALSO

193 .Xr bzip2 1 ,

194 .Xr compress 1 ,

195 .Xr xz 1 ,

196 .Xr fts 3 ,

197 .Xr zlib 3

198 .Sh HISTORY

199 The

200 .Nm

201 program was originally written by Jean-loup Gailly, licensed under

202 the GNU Public Licence.

203 Matthew R. Green wrote a simple front end for

204 .Nx 1.3

205 distribution media, based on the freely re-distributable zlib library.

206 It was enhanced to be mostly feature-compatible with the original

207 GNU

208 .Nm

209 program for

210 .Nx 2.0 .

211 .Pp

212 This implementation of

213 .Nm

214 was ported based on the

215 .Nx

216 .Nm ,

217 and first appeared in

218 .Fx 7.0 .

219 .Sh AUTHORS

220 .An -nosplit

221 This implementation of

222 .Nm

223 was written by

224 .An Matthew R. Green Aq Mt mrg@eterna.com.au

225 with unpack support written by

226 .An Xin LI Aq Mt delphij@FreeBSD.org .

227 .Sh BUGS

228 According to RFC 1952, the recorded file size is stored in a 32-bit

229 integer, therefore, it cannot represent files larger than 4GB.

230 This limitation also applies to

231 .Fl l

232 option of

233 .Nm

234 utility.