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BSDTAR(1)		  BSD 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.

     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 ex-
	     tracted, 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 be-
     fore 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 en-
	     tries in it will be appended to the current archive.  As a	simple
	     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-supported 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 en-
	     tries 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	     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
	     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 en-
	     tries 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 op-
	     tion 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 un-
	     less --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 ex-
	     tracted 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
	     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.

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

     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 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

     To	move file hierarchies, invoke tar as
	   tar -cf - -C	srcdir . | tar -xpBf - -C destdir
     or	more traditionally
	   cd srcdir ; tar -cf - . | (cd destdir ; tar -xpBf -)

     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.  Fi-
     nally, 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 ex-
     tract files to locations outside of the target directory.	This can po-
     tentially 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 re-
	     moves 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 an-
	     other 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-ex-
     isting 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 specification 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.  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
     POSIX and GNU violently disagree about the	meaning	of the -l option.  Be-
     cause of the potential for	disaster if someone expects one	behavior and
     gets the other, the -l option is deliberately broken in this implementa-
     tion.

     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	de-
     vice.  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) us-
     ing 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.

BSD				April 13, 2004				   BSD

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | FILES | EXIT STATUS | EXAMPLES | COMPATIBILITY | SECURITY | SEE ALSO | STANDARDS | HISTORY | BUGS

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