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- TAR(1) UNIX Programmer's Manual TAR(1)
-
-
-
- NAME
- tar - tape (or other media) file archiver
-
- SYNOPSIS
- tar -[BcdDhiklmopRstvxzZ] [-b N] [-f F] [-T F] [ filename or
- regexp ... ]
-
- DESCRIPTION
- tar provides a way to store many files into a single
- archive, which can be kept in another Unix file, stored on
- an I/O device such as tape, floppy, cartridge, or disk, sent
- over a network, or piped to another program. It is useful
- for making backup copies, or for packaging up a set of files
- to move them to another system.
-
- tar has existed since Version 7 Unix with very little
- change. It has been proposed as the standard format for
- interchange of files among systems that conform to the IEEE
- P1003 ``Portable Operating System'' standard.
-
- This version of tar supports some of the extensions which
- were proposed in the P1003 draft standards, including owner
- and group names, and support for named pipes, fifos, con-
- tiguous files, and block and character devices.
-
- When reading an archive, this version of tar continues after
- finding an error. Previous versions required the `i' option
- to ignore checksum errors.
-
- OPTIONS
- tar options can be specified in either of two ways. The
- usual Unix conventions can be used: each option is preceded
- by `-'; arguments directly follow each option; multiple
- options can be combined behind one `-' as long as they take
- no arguments. For compatability with the Unix tar program,
- the options may also be specified as ``keyletters,'' wherein
- all the option letters occur in the first argument to tar,
- with no `-', and their arguments, if any, occur in the
- second, third, ... arguments. Examples:
-
- Normal: tar -f arcname -cv file1 file2
-
- Old: tar fcv arcname file1 file2
-
- At least one of the -c, -t, -d, or -x options must be
- included. The rest are optional.
-
- Files to be operated upon are specified by a list of file
- names, which follows the option specifications (or can be
- read from a file by the -T option). Specifying a directory
- name causes that directory and all the files it contains to
- be (recursively) processed. If a full path name is speci-
- fied when creating an archive, it will be written to the
- archive without the initial "/", to allow the files to be
- later read into a different place than where they were
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- dumped from, and a warning will be printed. If files are
- extracted from an archive which contains full path names,
- they will be extracted relative to the current directory and
- a warning message printed.
-
- When extracting or listing files, the ``file names'' are
- treated as regular expressions, using mostly the same syntax
- as the shell. The shell actually matches each substring
- between ``/''s separately, while tar matches the entire
- string at once, so some anomalies will occur; e.g. ``*'' or
- ``?'' can match a ``/''. To specify a regular expression as
- an argument to tar, quote it so the shell will not expand
- it.
-
- -b N Specify a blocking factor for the archive. The block
- size will be N x 512 bytes. Larger blocks typically
- run faster and let you fit more data on a tape. The
- default blocking factor is set when tar is compiled,
- and is typically 20. There is no limit to the maximum
- block size, as long as enough memory can be allocated
- for it, and as long as the device containing the
- archive can read or write that block size.
-
- -B When reading an archive, reblock it as we read it.
- Normally, tar reads each block with a single read(2)
- system call. This does not work when reading from a
- pipe or network socket under Berkeley Unix; read(2)
- only gives as much data as has arrived at the moment.
- With this option, it will do multiple read(2)s to fill
- out to a record boundary, rather than reporting an
- error. This option is default when reading an archive
- from standard input, or over a network.
-
- -c Create an archive from a list of files.
-
- -d Diff an archive against the files in the file system.
- Reports differences in file size, mode, uid, gid, and
- contents. If a file exists on the tape, but not in the
- file system, that is reported. This option needs
- further work to be really useful.
-
- -D When creating an archive, only dump each directory
- itself; don't dump all the files inside the directory.
- In conjunction with find(1), this is useful in creating
- incremental dumps for archival backups, similar to
- those produced by dump(8).
-
- -f F Specify the filename of the archive. If the specified
- filename is ``-'', the archive is read from the stan-
- dard input or written to the standard output. If the
- -f option is not used, and the environment variable
- TAPE exists, its value will be used; otherwise, a
- default archive name (which was picked when tar was
- compiled) is used. The default is normally set to the
- ``first'' tape drive or other transportable I/O medium
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- on the system.
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- If the filename contains a colon before a slash, it is
- interpreted as a ``hostname:/file/name'' pair. tar
- will invoke the commands rsh and dd to access the
- specified file or device on the system hostname. If
- you need to do something unusual like rsh with a dif-
- ferent user name, use ``-f -'' and pipe it to rsh manu-
- ally.
-
- -h When creating an archive, if a symbolic link is encoun-
- tered, dump the file or directory to which it points,
- rather than dumping it as a symbolic link.
-
- -i When reading an archive, ignore blocks of zeros in the
- archive. Normally a block of zeros indicates the end
- of the archive, but in a damaged archive, or one which
- was created by appending several archives, this option
- allows tar to continue. It is not on by default
- because there is garbage written after the zeroed
- blocks by the Unix tar program. Note that with this
- option set, tar will read all the way to the end of the
- file, eliminating problems with multi-file tapes.
-
- -k When extracting files from an archive, keep existing
- files, rather than overwriting them with the version
- from the archive.
-
- -l When dumping the contents of a directory to an archive,
- stay within the local file system of that directory.
- This option only affects the files dumped because they
- are in a dumped directory; files named on the command
- line are always dumped, and they can be from various
- file systems. This is useful for making ``full dump''
- archival backups of a file system, as with the dump(8)
- command. Files which are skipped due to this option
- are mentioned on the standard error.
-
- -m When extracting files from an archive, set each file's
- modified timestamp to the current time, rather than
- extracting each file's modified timestamp from the
- archive.
-
- -o When creating an archive, write an old format archive,
- which does not include information about directories,
- pipes, fifos, contiguous files, or device files, and
- specifies file ownership by uid's and gid's rather than
- by user names and group names. In most cases, a
- ``new'' format archive can be read by an ``old'' tar
- program without serious trouble, so this option should
- seldom be needed.
-
- -p When extracting files from an archive, restore them to
- the same permissions that they had in the archive. If
- -p is not specified, the current umask limits the
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- permissions of the extracted files. See umask(2).
-
- -R With each message that tar produces, print the record
- number within the archive where the message occurred.
- This option is especially useful when reading damaged
- archives, since it helps to pinpoint the damaged sec-
- tion.
-
- -s When specifying a list of filenames to be listed or
- extracted from an archive, the -s flag specifies that
- the list is sorted into the same order as the tape.
- This allows a large list to be used, even on small
- machines, because the entire list need not be read into
- memory at once. Such a sorted list can easily be
- created by running ``tar -t'' on the archive and edit-
- ing its output.
-
- -t List a table of contents of an existing archive. If
- file names are specified, just list files matching the
- specified names. The listing appears on the standard
- output.
-
- -T F Rather than specifying file names or regular expres-
- sions as arguments to the tar command, this option
- specifies that they should be read from the file F, one
- per line. If the file name specified is ``-'', the
- list is read from the standard input. This option, in
- conjunction with the -s option, allows an arbitrarily
- large list of files to be processed, and allows the
- list to be piped to tar.
-
- -v Be verbose about the files that are being processed or
- listed. Normally, archive creation, file extraction,
- and differencing are silent, and archive listing just
- gives file names. The -v option causes an ``ls
- -l''-like listing to be produced. The output from -v
- appears on the standard output except when creating an
- archive (since the new archive might be on standard
- output), where it goes to the standard error output.
-
- -V Print the version and authors of the program.
-
- -x Extract files from an existing archive. If file names
- are specified, just extract files matching the speci-
- fied names, otherwise extract all the files in the
- archive.
-
- -z or -Z
- The archive should be compressed as it is written, or
- decompressed as it is read, using the compress(1) pro-
- gram. This option works on I/O devices and over the
- network, as well as on disk files; data to or from such
- devices is reblocked using a ``dd'' command to enforce
- the specified (or default) block size. The default
- compression parameters are used; if you need to
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- override them, avoid the ``z'' option and compress it
- yourself.
-
- AUTHORS
- Tar and compress were integrated for the MS-DOS release by
- Diomidis Spinellis <dds@doc.ic.ac.uk>.
- Tar was written by John Gilmore <gnu@toad.com>.
- Compress was written and improved by Spencer W. Thomas, Jim
- McKie, Steve Davies, Ken Turkowski, James A. Woods, Joe
- Orost and Diomidis Spinellis.
-
- SEE ALSO
- shar(1), tar(5), compress(1), ar(1), arc(1), cpio(1),
- dump(8), restore(8), restor(8), rsh(1), dd(1), find(1)
-
- BUGS
- The r, u, w, X, l, F, C, and digit options of Unix tar are
- not supported.
-
- Multiple-tape (or floppy) archives should be supported, but
- so far no clean way has been implemented.
-
- A bug in the Bourne Shell usually causes an extra newline to
- be written to the standard error when using compressed or
- remote archives.
-
- A bug in ``dd'' prevents turning off the ``x+y records
- in/out'' messages on the standard error when ``dd'' is used
- to reblock or transport an archive.
-
- On MS-DOS systems filename characters that are not supported
- by most MS-DOS shells (;=+<>|,*?:[]\ ) are silently con-
- verted into a circumflex (^) character. Filanemes longer
- than the ones supported by MS-DOS are silently truncated and
- can thus overwrite files named with the same initial charac-
- ters.
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