1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
|
BSDTAR(1) FreeBSD General Commands Manual BSDTAR(1)
NAME
tar -- manipulate tape archives
SYNOPSIS
tar [bundled-flags <args>] [<file> | <pattern> ...]
tar {-c} [options] [files | directories]
tar {-r | -u} -f archive-file [options] [files | directories]
tar {-t | -x} [options] [patterns]
DESCRIPTION
tar creates and manipulates streaming archive files. This implementation
can extract from tar, pax, cpio, zip, jar, ar, and ISO 9660 cdrom images
and can create tar, pax, cpio, ar, and shar archives.
The first synopsis form shows a ``bundled'' option word. This usage is
provided for compatibility with historical implementations. See COMPATI-
BILITY below for details.
The other synopsis forms show the preferred usage. The first option to
tar is a mode indicator from the following list:
-c Create a new archive containing the specified items.
-r Like -c, but new entries are appended to the archive. Note that
this only works on uncompressed archives stored in regular files.
The -f option is required.
-t List archive contents to stdout.
-u Like -r, but new entries are added only if they have a modifica-
tion date newer than the corresponding entry in the archive.
Note that this only works on uncompressed archives stored in reg-
ular files. The -f option is required.
-x Extract to disk from the archive. If a file with the same name
appears more than once in the archive, each copy will be
extracted, with later copies overwriting (replacing) earlier
copies.
In -c, -r, or -u mode, each specified file or directory is added to the
archive in the order specified on the command line. By default, the con-
tents of each directory are also archived.
In extract or list mode, the entire command line is read and parsed
before the archive is opened. The pathnames or patterns on the command
line indicate which items in the archive should be processed. Patterns
are shell-style globbing patterns as documented in tcsh(1).
OPTIONS
Unless specifically stated otherwise, options are applicable in all oper-
ating modes.
@archive
(c and r mode only) The specified archive is opened and the
entries in it will be appended to the current archive. As a sim-
ple example,
tar -c -f - newfile @original.tar
writes a new archive to standard output containing a file newfile
and all of the entries from original.tar. In contrast,
tar -c -f - newfile original.tar
creates a new archive with only two entries. Similarly,
tar -czf - --format pax @-
reads an archive from standard input (whose format will be deter-
mined automatically) and converts it into a gzip-compressed pax-
format archive on stdout. In this way, tar can be used to con-
vert archives from one format to another.
-b blocksize
Specify the block size, in 512-byte records, for tape drive I/O.
As a rule, this argument is only needed when reading from or
writing to tape drives, and usually not even then as the default
block size of 20 records (10240 bytes) is very common.
-C directory
In c and r mode, this changes the directory before adding the
following files. In x mode, change directories after opening the
archive but before extracting entries from the archive.
--check-links (-W check-links)
(c and r modes only) Issue a warning message unless all links to
each file are archived.
--exclude pattern (-W exclude=pattern)
Do not process files or directories that match the specified pat-
tern. Note that exclusions take precedence over patterns or
filenames specified on the command line.
--format format (-W format=format)
(c mode only) Use the specified format for the created archive.
Supported formats include ``cpio'', ``pax'', ``shar'', and
``ustar''. Other formats may also be supported; see
libarchive-formats(5) for more information about currently-sup-
ported formats.
-f file
Read the archive from or write the archive to the specified file.
The filename can be - for standard input or standard output. If
not specified, the default tape device will be used. (On
FreeBSD, the default tape device is /dev/sa0.)
--fast-read (-W fast-read)
(x and t mode only) Extract or list only the first archive entry
that matches each pattern or filename operand. Exit as soon as
each specified pattern or filename has been matched. By default,
the archive is always read to the very end, since there can be
multiple entries with the same name and, by convention, later
entries overwrite earlier entries. This option is provided as a
performance optimization.
-H (c and r mode only) Symbolic links named on the command line will
be followed; the target of the link will be archived, not the
link itself.
-h (c and r mode only) Synonym for -L.
-I Synonym for -T.
--include pattern (-W include=pattern)
Process only files or directories that match the specified pat-
tern. Note that exclusions specified with --exclude take prece-
dence over inclusions. If no inclusions are explicitly speci-
fied, all entries are processed by default. The --include option
is especially useful when filtering archives. For example, the
command
tar -c -f new.tar --include='*foo*' @old.tgz
creates a new archive new.tar containing only the entries from
old.tgz containing the string `foo'.
-j (c mode only) Compress the resulting archive with bzip2(1). In
extract or list modes, this option is ignored. Note that, unlike
other tar implementations, this implementation recognizes bzip2
compression automatically when reading archives.
-k (x mode only) Do not overwrite existing files. In particular, if
a file appears more than once in an archive, later copies will
not overwrite earlier copies.
-L (c and r mode only) All symbolic links will be followed. Nor-
mally, symbolic links are archived as such. With this option,
the target of the link will be archived instead.
-l This is a synonym for the --check-links option.
-m (x mode only) Do not extract modification time. By default, the
modification time is set to the time stored in the archive.
-n (c, r, u modes only) Do not recursively archive the contents of
directories.
--newer date (-W newer=date)
(c, r, u modes only) Only include files and directories newer
than the specified date. This compares ctime entries.
--newer-mtime date (-W newer-mtime=date)
(c, r, u modes only) Like --newer, except it compares mtime
entries instead of ctime entries.
--newer-than file (-W newer-than=file)
(c, r, u modes only) Only include files and directories newer
than the specified file. This compares ctime entries.
--newer-mtime-than file (-W newer-mtime-than=file)
(c, r, u modes only) Like --newer-than, except it compares mtime
entries instead of ctime entries.
--nodump (-W nodump)
(c and r modes only) Honor the nodump file flag by skipping this
file.
--null (-W null)
(use with -I, -T, or -X) Filenames or patterns are separated by
null characters, not by newlines. This is often used to read
filenames output by the -print0 option to find(1).
-O (x, t modes only) In extract (-x) mode, files will be written to
standard out rather than being extracted to disk. In list (-t)
mode, the file listing will be written to stderr rather than the
usual stdout.
-o (x mode only) Use the user and group of the user running the pro-
gram rather than those specified in the archive. Note that this
has no significance unless -p is specified, and the program is
being run by the root user. In this case, the file modes and
flags from the archive will be restored, but ACLs or owner infor-
mation in the archive will be discarded.
--one-file-system (-W one-file-system)
(c, r, and u modes) Do not cross mount points.
-P Preserve pathnames. By default, absolute pathnames (those that
begin with a / character) have the leading slash removed both
when creating archives and extracting from them. Also, tar will
refuse to extract archive entries whose pathnames contain .. or
whose target directory would be altered by a symlink. This
option suppresses these behaviors.
-p (x mode only) Preserve file permissions. Attempt to restore the
full permissions, including owner, file modes, file flags and
ACLs, if available, for each item extracted from the archive. By
default, newly-created files are owned by the user running tar,
the file mode is restored for newly-created regular files, and
all other types of entries receive default permissions. If tar
is being run by root, the default is to restore the owner unless
the -o option is also specified.
--strip-components count (-W strip-components=count)
(x and t mode only) Remove the specified number of leading path
elements. Pathnames with fewer elements will be silently
skipped. Note that the pathname is edited after checking inclu-
sion/exclusion patterns but before security checks.
-T filename
In x or t mode, tar will read the list of names to be extracted
from filename. In c mode, tar will read names to be archived
from filename. The special name ``-C'' on a line by itself will
cause the current directory to be changed to the directory speci-
fied on the following line. Names are terminated by newlines
unless --null is specified. Note that --null also disables the
special handling of lines containing ``-C''.
-U (x mode only) Unlink files before creating them. Without this
option, tar overwrites existing files, which preserves existing
hardlinks. With this option, existing hardlinks will be broken,
as will any symlink that would affect the location of an
extracted file.
--use-compress-program program
Pipe the input (in x or t mode) or the output (in c mode) through
program instead of using the builtin compression support.
-v Produce verbose output. In create and extract modes, tar will
list each file name as it is read from or written to the archive.
In list mode, tar will produce output similar to that of ls(1).
Additional -v options will provide additional detail.
-W longopt=value
Long options (preceded by --) are only supported directly on sys-
tems that have the getopt_long(3) function. The -W option can be
used to access long options on systems that do not support this
function.
-w Ask for confirmation for every action.
-X filename
Read a list of exclusion patterns from the specified file. See
--exclude for more information about the handling of exclusions.
-y (c mode only) Compress the resulting archive with bzip2(1). In
extract or list modes, this option is ignored. Note that, unlike
other tar implementations, this implementation recognizes bzip2
compression automatically when reading archives.
-z (c mode only) Compress the resulting archive with gzip(1). In
extract or list modes, this option is ignored. Note that, unlike
other tar implementations, this implementation recognizes gzip
compression automatically when reading archives.
ENVIRONMENT
The following environment variables affect the execution of tar:
LANG The locale to use. See environ(7) for more information.
TAPE The default tape device. The -f option overrides this.
TZ The timezone to use when displaying dates. See environ(7) for
more information.
FILES
/dev/sa0 The default tape device, if not overridden by the TAPE envi-
ronment variable or the -f option.
EXIT STATUS
The tar utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
The following creates a new archive called file.tar.gz that contains two
files source.c and source.h:
tar -czf file.tar.gz source.c source.h
To view a detailed table of contents for this archive:
tar -tvf file.tar.gz
To extract all entries from the archive on the default tape drive:
tar -x
To examine the contents of an ISO 9660 cdrom image:
tar -tf image.iso
To move file hierarchies, invoke tar as
tar -cf - -C srcdir . | tar -xpf - -C destdir
or more traditionally
cd srcdir ; tar -cf - . | (cd destdir ; tar -xpf -)
In create mode, the list of files and directories to be archived can also
include directory change instructions of the form -Cfoo/baz and archive
inclusions of the form @archive-file. For example, the command line
tar -c -f new.tar foo1 @old.tgz -C/tmp foo2
will create a new archive new.tar. tar will read the file foo1 from the
current directory and add it to the output archive. It will then read
each entry from old.tgz and add those entries to the output archive.
Finally, it will switch to the /tmp directory and add foo2 to the output
archive.
The --newer and --newer-mtime switches accept a variety of common date
and time specifications, including ``12 Mar 2005 7:14:29pm'',
``2005-03-12 19:14'', ``5 minutes ago'', and ``19:14 PST May 1''.
COMPATIBILITY
The bundled-arguments format is supported for compatibility with historic
implementations. It consists of an initial word (with no leading - char-
acter) in which each character indicates an option. Arguments follow as
separate words. The order of the arguments must match the order of the
corresponding characters in the bundled command word. For example,
tar tbf 32 file.tar
specifies three flags t, b, and f. The b and f flags both require argu-
ments, so there must be two additional items on the command line. The 32
is the argument to the b flag, and file.tar is the argument to the f
flag.
The mode options c, r, t, u, and x and the options b, f, l, m, o, v, and
w comply with SUSv2.
For maximum portability, scripts that invoke tar should use the bundled-
argument format above, should limit themselves to the c, t, and x modes,
and the b, f, m, v, and w options.
On systems that support getopt_long(), additional long options are avail-
able to improve compatibility with other tar implementations.
SECURITY
Certain security issues are common to many archiving programs, including
tar. In particular, carefully-crafted archives can request that tar
extract files to locations outside of the target directory. This can
potentially be used to cause unwitting users to overwrite files they did
not intend to overwrite. If the archive is being extracted by the supe-
ruser, any file on the system can potentially be overwritten. There are
three ways this can happen. Although tar has mechanisms to protect
against each one, savvy users should be aware of the implications:
o Archive entries can have absolute pathnames. By default, tar
removes the leading / character from filenames before restoring
them to guard against this problem.
o Archive entries can have pathnames that include .. components.
By default, tar will not extract files containing .. components
in their pathname.
o Archive entries can exploit symbolic links to restore files to
other directories. An archive can restore a symbolic link to
another directory, then use that link to restore a file into that
directory. To guard against this, tar checks each extracted path
for symlinks. If the final path element is a symlink, it will be
removed and replaced with the archive entry. If -U is specified,
any intermediate symlink will also be unconditionally removed.
If neither -U nor -P is specified, tar will refuse to extract the
entry.
To protect yourself, you should be wary of any archives that come from
untrusted sources. You should examine the contents of an archive with
tar -tf filename
before extraction. You should use the -k option to ensure that tar will
not overwrite any existing files or the -U option to remove any pre-
existing files. You should generally not extract archives while running
with super-user privileges. Note that the -P option to tar disables the
security checks above and allows you to extract an archive while preserv-
ing any absolute pathnames, .. components, or symlinks to other directo-
ries.
SEE ALSO
bzip2(1), cpio(1), gzip(1), mt(1), pax(1), shar(1), libarchive(3),
libarchive-formats(5), tar(5)
STANDARDS
There is no current POSIX standard for the tar command; it appeared in
ISO/IEC 9945-1:1996 (``POSIX.1'') but was dropped from IEEE Std
1003.1-2001 (``POSIX.1''). The options used by this implementation were
developed by surveying a number of existing tar implementations as well
as the old POSIX specification for tar and the current POSIX specifica-
tion for pax.
The ustar and pax interchange file formats are defined by IEEE Std
1003.1-2001 (``POSIX.1'') for the pax command.
HISTORY
A tar command appeared in Seventh Edition Unix, which was released in
January, 1979. There have been numerous other implementations, many of
which extended the file format. John Gilmore's pdtar public-domain
implementation (circa November, 1987) was quite influential, and formed
the basis of GNU tar. GNU tar was included as the standard system tar in
FreeBSD beginning with FreeBSD 1.0.
This is a complete re-implementation based on the libarchive(3) library.
BUGS
This program follows ISO/IEC 9945-1:1996 (``POSIX.1'') for the definition
of the -l option. Note that GNU tar prior to version 1.15 treated -l as
a synonym for the --one-file-system option.
The -C dir option may differ from historic implementations.
All archive output is written in correctly-sized blocks, even if the out-
put is being compressed. Whether or not the last output block is padded
to a full block size varies depending on the format and the output
device. For tar and cpio formats, the last block of output is padded to
a full block size if the output is being written to standard output or to
a character or block device such as a tape drive. If the output is being
written to a regular file, the last block will not be padded. Many com-
pressors, including gzip(1) and bzip2(1), complain about the null padding
when decompressing an archive created by tar, although they still extract
it correctly.
The compression and decompression is implemented internally, so there may
be insignificant differences between the compressed output generated by
tar -czf - file
and that generated by
tar -cf - file | gzip
The default should be to read and write archives to the standard I/O
paths, but tradition (and POSIX) dictates otherwise.
The r and u modes require that the archive be uncompressed and located in
a regular file on disk. Other archives can be modified using c mode with
the @archive-file extension.
To archive a file called @foo or -foo you must specify it as ./@foo or
./-foo, respectively.
In create mode, a leading ./ is always removed. A leading / is stripped
unless the -P option is specified.
There needs to be better support for file selection on both create and
extract.
There is not yet any support for multi-volume archives or for archiving
sparse files.
Converting between dissimilar archive formats (such as tar and cpio)
using the @- convention can cause hard link information to be lost.
(This is a consequence of the incompatible ways that different archive
formats store hardlink information.)
There are alternative long options for many of the short options that are
deliberately not documented.
FreeBSD 6.0 April 13, 2004 FreeBSD 6.0
|