1 .TH TAR 1
2 .SH NAME
3 tar \- archiver
4 .SH SYNOPSIS
5 .B tar
6 .I key
7 [
8 .I file ...
9 ]
10 .SH DESCRIPTION
11 .PP
12 .I Tar
13 saves and restores file trees.
14 It is most often used to transport a tree of files from one
15 system to another.
16 The
17 .I key
18 is a string that contains
19 at most one function letter plus optional modifiers.
20 Other arguments to the command are names of
21 files or directories to be dumped or restored.
22 A directory name implies all the contained
23 files and subdirectories (recursively).
24 .PP
25 The function is one of the following letters:
26 .TP
27 .B  c
28 Create a new archive with the given files as contents.
29 .TP
30 .B  r
31 The named files
32 are appended to the archive.
33 .TP
34 .B  t
35 List all occurrences of each 
36 .I file
37 in the archive, or of all files if there are no
38 .I file
39 arguments.
40 .TP
41 .B  x
42 Extract the named files from the archive.
43 If a file is a directory, the directory is extracted recursively.
44 Modes are restored if possible.
45 If no file argument is given, extract the entire archive.
46 If the archive contains multiple entries for a file,
47 the latest one wins.
48 .PP
49 The modifiers are:
50 .TP
51 .B f
52 Use the next argument as the name of the archive instead of
53 the default standard input (for keys
54 .B x
55 and
56 .BR t )
57 or standard output (for keys
58 .B c
59 and
60 .BR r ).
61 .TP
62 .B g
63 Use the next (numeric) argument as the group id for files in
64 the output archive.
65 .TP
66 .B k
67 (keep)
68 Modifies the behavior of
69 .B x
70 not to extract files which already exist.
71 .TP
72 .B m
73 Do not set the modification time on extracted files.
74 This is the default behavior; the flag exists only for compatibility with other tars.
75 .TP
76 .B p
77 Create archive in POSIX ustar format,
78 which raises the maximum pathname length from 100 to 256 bytes.
79 Ustar archives are recognised automatically by
80 .I tar
81 when reading archives.
82 This is the default behavior; the flag exists only for backwards compatibility
83 with older versions of tar.
84 .TP
85 .B P
86 Do not generate the POSIX ustar format.
87 .TP
88 .B R
89 When extracting, ignore leading slash on file names,
90 i.e., extract all files relative to the current directory.
91 .TP
92 .B T
93 Modifies the behavior of
94 .B x
95 to set the modified time
96 of each file to that specified in the archive.
97 .TP
98 .B u
99 Use the next (numeric) argument as the user id for files in
100 the output archive.  This is only useful when moving files to
101 a non-Plan 9 system.
102 .TP
103 .B v
104 (verbose)
105 Print the name of each file treated
106 preceded by the function letter.
107 With 
108 .BR t ,
109 give more details about the
110 archive entries.
111 .TP
112 .B z
113 Operate on compressed tar archives.
114 The type of compression is inferred from the file name extension:
115 .MR gzip (1)
116 for
117 .B .tar.gz
118 and
119 .BR .tgz ;
120 .I bzip2
121 (see
122 .MR gzip (1) )
123 for
124 .BR .tar.bz ,
125 .BR .tbz ,
126 .BR .tar.bz2 ,
127 and
128 .BR .tbz2 ;
129 .I compress
130 for
131 .B .tar.Z
132 and
133 .BR .tz .
134 If no extension matches,
135 .I gzip
136 is used.
137 The
138 .B z
139 flag is unnecessary (but allowed) when using the
140 .B t
141 and
142 .B x
143 verbs on archives with recognized extensions.
144 .SH EXAMPLES
145 .I Tar
146 can be used to copy hierarchies thus:
147 .IP
148 .EX
149 @{cd fromdir && tar cp .} | @{cd todir && tar xT}
150 .EE
151 .SH SOURCE
152 .B \*9/src/cmd/tar.c
153 .SH SEE ALSO
154 .I 9ar
155 in
156 .MR 9c (1) ,
157 .MR bundle (1)
158 .SH BUGS
159 There is no way to ask for any but the last
160 occurrence of a file.
161 .PP
162 File path names are limited to
163 100 characters
164 (256 when using ustar format).
165 .PP
166 The tar format allows specification of links and symbolic links,
167 concepts foreign to Plan 9: they are ignored.