Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
BSDTAR(1)		FreeBSD	General	Commands Manual		     BSDTAR(1)

     tar -- manipulate tape archives

     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]

     tar creates and manipulates streaming archive files.

     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

     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	XXXX.

     Unless specifically stated	otherwise, options are applicable in all oper-
     ating modes.

	     (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 Free-
	     BSD, 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.

     --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
		   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	     If	POSIXLY_CORRECT	is specified in	the environment, this is a
	     synonym for the --check-links option.  Otherwise, an error	will
	     be	displayed.  Users who desire behavior compatible with GNU tar
	     should use	the --one-file-system option instead.

     -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

     --nodump (-W nodump)
	     (c	and r modes only) Honor	the nodump file	flag by	skipping this

     -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.

     -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.

     -T	filename
	     (c	mode only) Read	names to be archived from filename.  Names are
	     terminated	by newlines.  The special name ``-C'' will cause the
	     current directory to be changed to	the directory specified	on the
	     following line.

     -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.

     -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

     -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.

     The following environment variables affect	the execution of tar:

     LANG	The locale to use.  See	environ(7) for more information.

		If this	environment variable is	defined, the -l	option will be
		interpreted in accordance with ISO/IEC 9945-1:1996

     TAPE	The default tape device.  The -f option	overrides this.

     TZ		The timezone to	use when displaying dates.  See	environ(7) for
		more information.

     /dev/sa0	The default tape device, if not	overridden by the TAPE envi-
		ronment	variable or the	-f option.

     The tar utility exits 0 on	success, and >0	if an error occurs.

     The following creates a new archive called	file.tar that contains two
     files source.c and	source.h:
	   tar -czf file.tar source.c source.h

     To	view a detailed	table of contents for this archive:
	   tar -tvf file.tar

     To	extract	all entries from the archive on	the default tape drive:
	   tar -x

     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

     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

     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.

     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
     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-

     bzip2(1), cpio(1),	gzip(1), mt(1),	pax(1),	shar(1), libarchive(3),
     libarchive-formats(5), tar(5)

     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.

     A tar command appeared in Seventh Edition Unix.  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.

     POSIX and GNU violently disagree about the	meaning	of the -l option.
     Because of	the potential for disaster if someone expects one behavior and
     gets the other, the -l option is deliberately broken in this implementa-

     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

     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	5.4			April 13, 2004			   FreeBSD 5.4


Want to link to this manual page? Use this URL:

home | help