1 .\" Copyright (c) 2003 Tim Kientzle
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25 .\" $FreeBSD: src/usr.bin/tar/bsdtar.1,v 1.32 2006/05/01 01:34:21 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.
54 The first synopsis form shows a
57 This usage is provided for compatibility with historical implementations.
58 See COMPATIBILITY below for details.
60 The other synopsis forms show the preferred usage.
63 is a mode indicator from the following list:
64 .Bl -tag -compact -width indent
66 Create a new archive containing the specified items.
70 but new entries are appended to the archive.
71 Note that this only works on uncompressed archives stored in regular files.
76 List archive contents to stdout.
80 but new entries are added only if they have a modification date
81 newer than the corresponding entry in the archive.
82 Note that this only works on uncompressed archives stored in regular files.
87 Extract to disk from the archive.
88 If a file with the same name appears more than once in the archive,
89 each copy will be extracted, with later copies overwriting (replacing)
98 mode, each specified file or directory is added to the
99 archive in the order specified on the command line.
100 By default, the contents of each directory are also archived.
102 In extract or list mode, the entire command line
103 is read and parsed before the archive is opened.
104 The pathnames or patterns on the command line indicate
105 which items in the archive should be processed.
106 Patterns are shell-style globbing patterns as
110 Unless specifically stated otherwise, options are applicable in
112 .Bl -tag -width indent
113 .It Cm @ Ns Pa archive
115 The specified archive is opened and the entries
116 in it will be appended to the current archive.
118 .Dl Nm Fl c Fl f Pa - Pa newfile Cm @ Ns Pa original.tar
119 writes a new archive to standard output containing a file
121 and all of the entries from
124 .Dl Nm Fl c Fl f Pa - Pa newfile Pa original.tar
125 creates a new archive with only two entries.
127 .Dl Nm Fl czf Pa - Fl -format Cm pax Cm @ Ns Pa -
128 reads an archive from standard input (whose format will be determined
129 automatically) and converts it into a gzip-compressed
130 pax-format archive on stdout.
133 can be used to convert archives from one format to another.
134 .It Fl b Ar blocksize
135 Specify the block size, in 512-byte records, for tape drive I/O.
136 As a rule, this argument is only needed when reading from or writing
137 to tape drives, and usually not even then as the default block size of
138 20 records (10240 bytes) is very common.
139 .It Fl C Ar directory
140 In c and r mode, this changes the directory before adding
142 In x mode, change directories after opening the archive
143 but before extracting entries from the archive.
144 .It Fl -check-links ( Fl W Cm check-links )
146 Issue a warning message unless all links to each file are archived.
147 .It Fl -exclude Ar pattern ( Fl W Cm exclude Ns = Ns Ar pattern )
148 Do not process files or directories that match the
150 Note that exclusions take precedence over patterns or filenames
151 specified on the command line.
152 .It Fl -format Ar format ( Fl W Cm format Ns = Ns Ar format )
154 Use the specified format for the created archive.
155 Supported formats include
161 Other formats may also be supported; see
162 .Xr libarchive-formats 5
163 for more information about currently-supported formats.
165 Read the archive from or write the archive to the specified file.
168 for standard input or standard output.
169 If not specified, the default tape device will be used.
172 the default tape device is
174 .It Fl -fast-read ( Fl W Cm fast-read )
176 Extract or list only the first archive entry that matches each pattern
178 Exit as soon as each specified pattern or filename has been matched.
179 By default, the archive is always read to the very end, since
180 there can be multiple entries with the same name and, by convention,
181 later entries overwrite earlier entries.
182 This option is provided as a performance optimization.
185 Symbolic links named on the command line will be followed; the
186 target of the link will be archived, not the link itself.
194 .It Fl -include Ar pattern ( Fl W Cm include Ns = Ns Ar pattern )
195 Process only files or directories that match the specified pattern.
196 Note that exclusions specified with
198 take precedence over inclusions.
199 If no inclusions are explicitly specified, all entries are processed by
203 option is especially useful when filtering archives.
204 For example, the command
205 .Dl Nm Fl c Fl f Pa new.tar Fl -include='*foo*' Cm @ Ns Pa old.tgz
206 creates a new archive
208 containing only the entries from
210 containing the string
214 Compress the resulting archive with
216 In extract or list modes, this option is ignored.
217 Note that, unlike other
219 implementations, this implementation recognizes bzip2 compression
220 automatically when reading archives.
223 Do not overwrite existing files.
224 In particular, if a file appears more than once in an archive,
225 later copies will not overwrite earlier copies.
228 All symbolic links will be followed.
229 Normally, symbolic links are archived as such.
230 With this option, the target of the link will be archived instead.
234 is specified in the environment, this is a synonym for the
237 Otherwise, an error will be displayed.
238 Users who desire behavior compatible with GNU tar should use
244 Do not extract modification time.
245 By default, the modification time is set to the time stored in the archive.
248 Do not recursively archive the contents of directories.
249 .It Fl -newer Ar date ( Fl W Cm newer Ns = Ns Ar date )
251 Only include files and directories newer than the specified date.
252 This compares ctime entries.
253 .It Fl -newer-mtime Ar date ( Fl W Cm newer-mtime Ns = Ns Ar date )
257 except it compares mtime entries instead of ctime entries.
258 .It Fl -newer-than Pa file ( Fl W Cm newer-than Ns = Ns Pa file )
260 Only include files and directories newer than the specified file.
261 This compares ctime entries.
262 .It Fl -newer-mtime-than Pa file ( Fl W Cm newer-mtime-than Ns = Ns Pa file )
266 except it compares mtime entries instead of ctime entries.
267 .It Fl -nodump ( Fl W Cm nodump )
269 Honor the nodump file flag by skipping this file.
270 .It Fl -null ( Fl W Cm null )
276 Filenames or patterns are separated by null characters,
278 This is often used to read filenames output by the
284 In extract (-x) mode, files will be written to standard out rather than
285 being extracted to disk.
286 In list (-t) mode, the file listing will be written to stderr rather than
290 Use the user and group of the user running the program rather
291 than those specified in the archive.
292 Note that this has no significance unless
294 is specified, and the program is being run by the root user.
295 In this case, the file modes and flags from
296 the archive will be restored, but ACLs or owner information in
297 the archive will be discarded.
298 .It Fl -one-file-system ( Fl W Cm one-file-system )
300 Do not cross mount points.
303 By default, absolute pathnames (those that begin with a /
304 character) have the leading slash removed both when creating archives
305 and extracting from them.
308 will refuse to extract archive entries whose pathnames contain
310 or whose target directory would be altered by a symlink.
311 This option suppresses these behaviors.
314 Preserve file permissions.
315 Attempt to restore the full permissions, including owner, file modes, file
316 flags and ACLs, if available, for each item extracted from the archive.
317 By default, newly-created files are owned by the user running
319 the file mode is restored for newly-created regular files, and
320 all other types of entries receive default permissions.
323 is being run by root, the default is to restore the owner unless the
325 option is also specified.
326 .It Fl -strip-components Ar count ( Fl W Cm strip-components Ns = Ns Ar count )
328 Remove the specified number of leading path elements.
329 Pathnames with fewer elements will be silently skipped.
330 Note that the pathname is edited after checking inclusion/exclusion patterns
331 but before security checks.
335 will read the list of names to be extracted from
339 will read names to be archived from
343 on a line by itself will cause the current directory to be changed to
344 the directory specified on the following line.
345 Names are terminated by newlines unless
350 also disables the special handling of lines containing
354 Unlink files before creating them.
357 overwrites existing files, which preserves existing hardlinks.
358 With this option, existing hardlinks will be broken, as will any
359 symlink that would affect the location of an extracted file.
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.
418 .It Ev POSIXLY_CORRECT
419 If this environment variable is defined, the
421 option will be interpreted in accordance with
424 The default tape device.
427 option overrides this.
429 The timezone to use when displaying dates.
432 for more information.
435 .Bl -tag -width ".Ev BLOCKSIZE"
437 The default tape device, if not overridden by the
439 environment variable or the
446 The following creates a new archive
449 that contains two files
453 .Dl Nm Fl czf Pa file.tar.gz Pa source.c Pa source.h
455 To view a detailed table of contents for this
457 .Dl Nm Fl tvf Pa file.tar.gz
459 To extract all entries from the archive on
460 the default tape drive:
463 To move file hierarchies, invoke
466 .Dl Nm Fl cf Pa - Fl C Pa srcdir\ . | Nm Fl xpf Pa - Fl C Pa destdir
467 or more traditionally
468 .Dl cd srcdir \&; Nm Fl cf Pa -\ . | ( cd destdir \&; Nm Fl xpf Pa - )
470 In create mode, the list of files and directories to be archived
471 can also include directory change instructions of the form
473 and archive inclusions of the form
474 .Cm @ Ns Pa archive-file .
475 For example, the command line
476 .Dl Nm Fl c Fl f Pa new.tar Pa foo1 Cm @ Ns Pa old.tgz Cm -C Ns Pa /tmp Pa foo2
477 will create a new archive
482 from the current directory and add it to the output archive.
483 It will then read each entry from
485 and add those entries to the output archive.
486 Finally, it will switch to the
490 to the output archive.
496 switches accept a variety of common date and time specifications, including
497 .Dq 12 Mar 2005 7:14:29pm ,
498 .Dq 2005-03-12 19:14 ,
501 .Dq 19:14 PST May 1 .
503 The bundled-arguments format is supported for compatibility
504 with historic implementations.
505 It consists of an initial word (with no leading - character) in which
506 each character indicates an option.
507 Arguments follow as separate words.
508 The order of the arguments must match the order
509 of the corresponding characters in the bundled command word.
511 .Dl Nm Cm tbf 32 Pa file.tar
512 specifies three flags
521 flags both require arguments,
522 so there must be two additional items
526 is the argument to the
530 is the argument to the
534 The mode options c, r, t, u, and x and the options
535 b, f, l, m, o, v, and w comply with SUSv2.
537 For maximum portability, scripts that invoke
539 should use the bundled-argument format above, should limit
554 On systems that support getopt_long(), additional long options
555 are available to improve compatibility with other tar implementations.
557 Certain security issues are common to many archiving programs, including
559 In particular, carefully-crafted archives can request that
561 extract files to locations outside of the target directory.
562 This can potentially be used to cause unwitting users to overwrite
563 files they did not intend to overwrite.
564 If the archive is being extracted by the superuser, any file
565 on the system can potentially be overwritten.
566 There are three ways this can happen.
569 has mechanisms to protect against each one,
570 savvy users should be aware of the implications:
571 .Bl -bullet -width indent
573 Archive entries can have absolute pathnames.
578 character from filenames before restoring them to guard against this problem.
580 Archive entries can have pathnames that include
585 will not extract files containing
587 components in their pathname.
589 Archive entries can exploit symbolic links to restore
590 files to other directories.
591 An archive can restore a symbolic link to another directory,
592 then use that link to restore a file into that directory.
593 To guard against this,
595 checks each extracted path for symlinks.
596 If the final path element is a symlink, it will be removed
597 and replaced with the archive entry.
600 is specified, any intermediate symlink will also be unconditionally removed.
607 will refuse to extract the entry.
609 To protect yourself, you should be wary of any archives that
610 come from untrusted sources.
611 You should examine the contents of an archive with
612 .Dl Nm Fl tf Pa filename
616 option to ensure that
618 will not overwrite any existing files or the
620 option to remove any pre-existing files.
621 You should generally not extract archives while running with super-user
627 disables the security checks above and allows you to extract
628 an archive while preserving any absolute pathnames,
630 components, or symlinks to other directories.
639 .Xr libarchive-formats 5 ,
642 There is no current POSIX standard for the tar command; it appeared
647 The options used by this implementation were developed by surveying a
648 number of existing tar implementations as well as the old POSIX specification
649 for tar and the current POSIX specification for pax.
651 The ustar and pax interchange file formats are defined by
657 command appeared in Seventh Edition Unix.
658 There have been numerous other implementations,
659 many of which extended the file format.
662 public-domain implementation (circa November, 1987)
663 was quite influential, and formed the basis of GNU tar.
664 GNU tar was included as the standard system tar
670 This is a complete re-implementation based on the
674 POSIX and GNU violently disagree about the meaning of the
677 Because of the potential for disaster if someone expects
678 one behavior and gets the other, the
680 option is deliberately broken in this implementation.
684 option may differ from historic implementations.
686 All archive output is written in correctly-sized blocks, even
687 if the output is being compressed.
688 Whether or not the last output block is padded to a full
689 block size varies depending on the format and the
691 For tar and cpio formats, the last block of output is padded
692 to a full block size if the output is being
693 written to standard output or to a character or block device such as
695 If the output is being written to a regular file, the last block
697 Many compressors, including
701 complain about the null padding when decompressing an archive created by
703 although they still extract it correctly.
705 The compression and decompression is implemented internally, so
706 there may be insignificant differences between the compressed output
708 .Dl Nm Fl czf Pa - file
709 and that generated by
710 .Dl Nm Fl cf Pa - file | Nm gzip
712 The default should be to read and write archives to the standard I/O paths,
713 but tradition (and POSIX) dictates otherwise.
719 modes require that the archive be uncompressed
720 and located in a regular file on disk.
721 Other archives can be modified using
727 To archive a file called
731 you must specify it as
737 In create mode, a leading
742 is stripped unless the
746 There needs to be better support for file selection on both create
749 There is not yet any support for multi-volume archives or for archiving
752 Converting between dissimilar archive formats (such as tar and cpio) using the
754 convention can cause hard link information to be lost.
755 (This is a consequence of the incompatible ways that different archive
756 formats store hardlink information.)
758 There are alternative long options for many of the short options that
759 are deliberately not documented.