1 .\" Copyright (c) 2003-2007 Tim Kientzle
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25 .\" $FreeBSD: src/usr.bin/tar/bsdtar.1,v 1.37 2008/01/22 07:23:44 kientzle Exp $
32 .Nd manipulate tape archives
35 .Op Ar bundled-flags Ao args Ac
36 .Op Ao Ar file Ac | Ao Ar pattern Ac ...
40 .Op Ar files | directories
45 .Op Ar files | directories
52 creates and manipulates streaming archive files.
53 This implementation can extract from tar, pax, cpio, zip, jar, ar,
54 and ISO 9660 cdrom images and can create tar, pax, cpio, ar,
57 The first synopsis form shows a
60 This usage is provided for compatibility with historical implementations.
61 See COMPATIBILITY below for details.
63 The other synopsis forms show the preferred usage.
66 is a mode indicator from the following list:
67 .Bl -tag -compact -width indent
69 Create a new archive containing the specified items.
73 but new entries are appended to the archive.
74 Note that this only works on uncompressed archives stored in regular files.
79 List archive contents to stdout.
83 but new entries are added only if they have a modification date
84 newer than the corresponding entry in the archive.
85 Note that this only works on uncompressed archives stored in regular files.
90 Extract to disk from the archive.
91 If a file with the same name appears more than once in the archive,
92 each copy will be extracted, with later copies overwriting (replacing)
101 mode, each specified file or directory is added to the
102 archive in the order specified on the command line.
103 By default, the contents of each directory are also archived.
105 In extract or list mode, the entire command line
106 is read and parsed before the archive is opened.
107 The pathnames or patterns on the command line indicate
108 which items in the archive should be processed.
109 Patterns are shell-style globbing patterns as
113 Unless specifically stated otherwise, options are applicable in
115 .Bl -tag -width indent
116 .It Cm @ Ns Pa archive
118 The specified archive is opened and the entries
119 in it will be appended to the current archive.
121 .Dl Nm Fl c Fl f Pa - Pa newfile Cm @ Ns Pa original.tar
122 writes a new archive to standard output containing a file
124 and all of the entries from
127 .Dl Nm Fl c Fl f Pa - Pa newfile Pa original.tar
128 creates a new archive with only two entries.
130 .Dl Nm Fl czf Pa - Fl -format Cm pax Cm @ Ns Pa -
131 reads an archive from standard input (whose format will be determined
132 automatically) and converts it into a gzip-compressed
133 pax-format archive on stdout.
136 can be used to convert archives from one format to another.
137 .It Fl b Ar blocksize
138 Specify the block size, in 512-byte records, for tape drive I/O.
139 As a rule, this argument is only needed when reading from or writing
140 to tape drives, and usually not even then as the default block size of
141 20 records (10240 bytes) is very common.
142 .It Fl C Ar directory
143 In c and r mode, this changes the directory before adding
145 In x mode, change directories after opening the archive
146 but before extracting entries from the archive.
147 .It Fl -check-links ( Fl W Cm check-links )
149 Issue a warning message unless all links to each file are archived.
150 .It Fl -exclude Ar pattern ( Fl W Cm exclude Ns = Ns Ar pattern )
151 Do not process files or directories that match the
153 Note that exclusions take precedence over patterns or filenames
154 specified on the command line.
155 .It Fl -format Ar format ( Fl W Cm format Ns = Ns Ar format )
157 Use the specified format for the created archive.
158 Supported formats include
164 Other formats may also be supported; see
165 .Xr libarchive-formats 5
166 for more information about currently-supported formats.
168 Read the archive from or write the archive to the specified file.
171 for standard input or standard output.
172 If not specified, the default tape device will be used.
175 the default tape device is
177 .It Fl -fast-read ( Fl W Cm fast-read )
179 Extract or list only the first archive entry that matches each pattern
181 Exit as soon as each specified pattern or filename has been matched.
182 By default, the archive is always read to the very end, since
183 there can be multiple entries with the same name and, by convention,
184 later entries overwrite earlier entries.
185 This option is provided as a performance optimization.
188 Symbolic links named on the command line will be followed; the
189 target of the link will be archived, not the link itself.
197 .It Fl -include Ar pattern ( Fl W Cm include Ns = Ns Ar pattern )
198 Process only files or directories that match the specified pattern.
199 Note that exclusions specified with
201 take precedence over inclusions.
202 If no inclusions are explicitly specified, all entries are processed by
206 option is especially useful when filtering archives.
207 For example, the command
208 .Dl Nm Fl c Fl f Pa new.tar Fl -include='*foo*' Cm @ Ns Pa old.tgz
209 creates a new archive
211 containing only the entries from
213 containing the string
217 Compress the resulting archive with
219 In extract or list modes, this option is ignored.
220 Note that, unlike other
222 implementations, this implementation recognizes bzip2 compression
223 automatically when reading archives.
226 Do not overwrite existing files.
227 In particular, if a file appears more than once in an archive,
228 later copies will not overwrite earlier copies.
231 All symbolic links will be followed.
232 Normally, symbolic links are archived as such.
233 With this option, the target of the link will be archived instead.
235 This is a synonym for the
240 Do not extract modification time.
241 By default, the modification time is set to the time stored in the archive.
244 Do not recursively archive the contents of directories.
245 .It Fl -newer Ar date ( Fl W Cm newer Ns = Ns Ar date )
247 Only include files and directories newer than the specified date.
248 This compares ctime entries.
249 .It Fl -newer-mtime Ar date ( Fl W Cm newer-mtime Ns = Ns Ar date )
253 except it compares mtime entries instead of ctime entries.
254 .It Fl -newer-than Pa file ( Fl W Cm newer-than Ns = Ns Pa file )
256 Only include files and directories newer than the specified file.
257 This compares ctime entries.
258 .It Fl -newer-mtime-than Pa file ( Fl W Cm newer-mtime-than Ns = Ns Pa file )
262 except it compares mtime entries instead of ctime entries.
263 .It Fl -nodump ( Fl W Cm nodump )
265 Honor the nodump file flag by skipping this file.
266 .It Fl -null ( Fl W Cm null )
272 Filenames or patterns are separated by null characters,
274 This is often used to read filenames output by the
280 In extract (-x) mode, files will be written to standard out rather than
281 being extracted to disk.
282 In list (-t) mode, the file listing will be written to stderr rather than
286 Use the user and group of the user running the program rather
287 than those specified in the archive.
288 Note that this has no significance unless
290 is specified, and the program is being run by the root user.
291 In this case, the file modes and flags from
292 the archive will be restored, but ACLs or owner information in
293 the archive will be discarded.
294 .It Fl -one-file-system ( Fl W Cm one-file-system )
296 Do not cross mount points.
299 By default, absolute pathnames (those that begin with a /
300 character) have the leading slash removed both when creating archives
301 and extracting from them.
304 will refuse to extract archive entries whose pathnames contain
306 or whose target directory would be altered by a symlink.
307 This option suppresses these behaviors.
310 Preserve file permissions.
311 Attempt to restore the full permissions, including owner, file modes, file
312 flags and ACLs, if available, for each item extracted from the archive.
313 By default, newly-created files are owned by the user running
315 the file mode is restored for newly-created regular files, and
316 all other types of entries receive default permissions.
319 is being run by root, the default is to restore the owner unless the
321 option is also specified.
322 .It Fl -strip-components Ar count ( Fl W Cm strip-components Ns = Ns Ar count )
324 Remove the specified number of leading path elements.
325 Pathnames with fewer elements will be silently skipped.
326 Note that the pathname is edited after checking inclusion/exclusion patterns
327 but before security checks.
331 will read the list of names to be extracted from
335 will read names to be archived from
339 on a line by itself will cause the current directory to be changed to
340 the directory specified on the following line.
341 Names are terminated by newlines unless
346 also disables the special handling of lines containing
350 Unlink files before creating them.
353 overwrites existing files, which preserves existing hardlinks.
354 With this option, existing hardlinks will be broken, as will any
355 symlink that would affect the location of an extracted file.
356 .It Fl -use-compress-program Ar program
357 Pipe the input (in x or t mode) or the output (in c mode) through
359 instead of using the builtin compression support.
361 Produce verbose output.
362 In create and extract modes,
364 will list each file name as it is read from or written to
368 will produce output similar to that of
372 options will provide additional detail.
373 .It Fl W Ar longopt=value
374 Long options (preceded by
376 are only supported directly on systems that have the
381 option can be used to access long options on systems that
382 do not support this function.
384 Ask for confirmation for every action.
386 Read a list of exclusion patterns from the specified file.
389 for more information about the handling of exclusions.
392 Compress the resulting archive with
394 In extract or list modes, this option is ignored.
395 Note that, unlike other
397 implementations, this implementation recognizes bzip2 compression
398 automatically when reading archives.
401 Compress the resulting archive with
403 In extract or list modes, this option is ignored.
404 Note that, unlike other
406 implementations, this implementation recognizes gzip compression
407 automatically when reading archives.
410 The following environment variables affect the execution of
412 .Bl -tag -width ".Ev BLOCKSIZE"
417 for more information.
419 The default tape device.
422 option overrides this.
424 The timezone to use when displaying dates.
427 for more information.
430 .Bl -tag -width ".Ev BLOCKSIZE"
432 The default tape device, if not overridden by the
434 environment variable or the
441 The following creates a new archive
444 that contains two files
448 .Dl Nm Fl czf Pa file.tar.gz Pa source.c Pa source.h
450 To view a detailed table of contents for this
452 .Dl Nm Fl tvf Pa file.tar.gz
454 To extract all entries from the archive on
455 the default tape drive:
458 To examine the contents of an ISO 9660 cdrom image:
459 .Dl Nm Fl tf Pa image.iso
461 To move file hierarchies, invoke
464 .Dl Nm Fl cf Pa - Fl C Pa srcdir\ . | Nm Fl xpf Pa - Fl C Pa destdir
465 or more traditionally
466 .Dl cd srcdir \&; Nm Fl cf Pa -\ . | ( cd destdir \&; Nm Fl xpf Pa - )
468 In create mode, the list of files and directories to be archived
469 can also include directory change instructions of the form
471 and archive inclusions of the form
472 .Cm @ Ns Pa archive-file .
473 For example, the command line
474 .Dl Nm Fl c Fl f Pa new.tar Pa foo1 Cm @ Ns Pa old.tgz Cm -C Ns Pa /tmp Pa foo2
475 will create a new archive
480 from the current directory and add it to the output archive.
481 It will then read each entry from
483 and add those entries to the output archive.
484 Finally, it will switch to the
488 to the output archive.
494 switches accept a variety of common date and time specifications, including
495 .Dq 12 Mar 2005 7:14:29pm ,
496 .Dq 2005-03-12 19:14 ,
499 .Dq 19:14 PST May 1 .
501 The bundled-arguments format is supported for compatibility
502 with historic implementations.
503 It consists of an initial word (with no leading - character) in which
504 each character indicates an option.
505 Arguments follow as separate words.
506 The order of the arguments must match the order
507 of the corresponding characters in the bundled command word.
509 .Dl Nm Cm tbf 32 Pa file.tar
510 specifies three flags
519 flags both require arguments,
520 so there must be two additional items
524 is the argument to the
528 is the argument to the
532 The mode options c, r, t, u, and x and the options
533 b, f, l, m, o, v, and w comply with SUSv2.
535 For maximum portability, scripts that invoke
537 should use the bundled-argument format above, should limit
552 On systems that support getopt_long(), additional long options
553 are available to improve compatibility with other tar implementations.
555 Certain security issues are common to many archiving programs, including
557 In particular, carefully-crafted archives can request that
559 extract files to locations outside of the target directory.
560 This can potentially be used to cause unwitting users to overwrite
561 files they did not intend to overwrite.
562 If the archive is being extracted by the superuser, any file
563 on the system can potentially be overwritten.
564 There are three ways this can happen.
567 has mechanisms to protect against each one,
568 savvy users should be aware of the implications:
569 .Bl -bullet -width indent
571 Archive entries can have absolute pathnames.
576 character from filenames before restoring them to guard against this problem.
578 Archive entries can have pathnames that include
583 will not extract files containing
585 components in their pathname.
587 Archive entries can exploit symbolic links to restore
588 files to other directories.
589 An archive can restore a symbolic link to another directory,
590 then use that link to restore a file into that directory.
591 To guard against this,
593 checks each extracted path for symlinks.
594 If the final path element is a symlink, it will be removed
595 and replaced with the archive entry.
598 is specified, any intermediate symlink will also be unconditionally removed.
605 will refuse to extract the entry.
607 To protect yourself, you should be wary of any archives that
608 come from untrusted sources.
609 You should examine the contents of an archive with
610 .Dl Nm Fl tf Pa filename
614 option to ensure that
616 will not overwrite any existing files or the
618 option to remove any pre-existing files.
619 You should generally not extract archives while running with super-user
625 disables the security checks above and allows you to extract
626 an archive while preserving any absolute pathnames,
628 components, or symlinks to other directories.
637 .Xr libarchive-formats 5 ,
640 There is no current POSIX standard for the tar command; it appeared
645 The options used by this implementation were developed by surveying a
646 number of existing tar implementations as well as the old POSIX specification
647 for tar and the current POSIX specification for pax.
649 The ustar and pax interchange file formats are defined by
655 command appeared in Seventh Edition Unix, which was released in January, 1979.
656 There have been numerous other implementations,
657 many of which extended the file format.
660 public-domain implementation (circa November, 1987)
661 was quite influential, and formed the basis of GNU tar.
662 GNU tar was included as the standard system tar
668 This is a complete re-implementation based on the
674 for the definition of the
677 Note that GNU tar prior to version 1.15 treated
685 option may differ from historic implementations.
687 All archive output is written in correctly-sized blocks, even
688 if the output is being compressed.
689 Whether or not the last output block is padded to a full
690 block size varies depending on the format and the
692 For tar and cpio formats, the last block of output is padded
693 to a full block size if the output is being
694 written to standard output or to a character or block device such as
696 If the output is being written to a regular file, the last block
698 Many compressors, including
702 complain about the null padding when decompressing an archive created by
704 although they still extract it correctly.
706 The compression and decompression is implemented internally, so
707 there may be insignificant differences between the compressed output
709 .Dl Nm Fl czf Pa - file
710 and that generated by
711 .Dl Nm Fl cf Pa - file | Nm gzip
713 The default should be to read and write archives to the standard I/O paths,
714 but tradition (and POSIX) dictates otherwise.
720 modes require that the archive be uncompressed
721 and located in a regular file on disk.
722 Other archives can be modified using
728 To archive a file called
732 you must specify it as
738 In create mode, a leading
743 is stripped unless the
747 There needs to be better support for file selection on both create
750 There is not yet any support for multi-volume archives or for archiving
753 Converting between dissimilar archive formats (such as tar and cpio) using the
755 convention can cause hard link information to be lost.
756 (This is a consequence of the incompatible ways that different archive
757 formats store hardlink information.)
759 There are alternative long options for many of the short options that
760 are deliberately not documented.