tar(1)
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TAR(1) NetBSD Reference Manual TAR(1)
NAME
tar - tape archiver; manipulate ``tar'' archive files
SYNOPSIS
tar [[-]] [bundled-options] [[gnu-style-flags]] [tarfile] [blocksize]
[exclude-file] [filenames] [-C directory-name]
DESCRIPTION
tar is short for ``tape archiver'', so named for historical reasons; the
tar program creates, adds files to, or extracts files from an archive
file in ``tar'' format, called a tarfile. A tarfile is often a magnetic
tape, but can be a floppy diskette or any regular disk file.
The first argument word of the tar command line is usually a command word
of bundled function and modifier letters, optionally preceded by a dash;
it must contain exactly one function letter from the set A, c, d, r, t,
u, x, for append, create, difference, replace, table of contents, update,
and extract (further described below). The command word can also contain
other function modifiers described below, some of which will take argu-
ments from the command line in the order they are specified in the com-
mand word (review the EXAMPLES section). Functions and function modi-
fiers can also be specified with the GNU argument convention (preceded by
two dashes, one function or modifier per word. Command-line arguments
that specify files to add to, extract from, or list from an archive may
be given as shell pattern matching strings.
FUNCTIONS
Exactly one of the following functions must be specified.
-A
--catenate
--concatenate Append the contents of named file, which must itself be a
tar archive, to the end of the archive (erasing the old
end-of-archive block). This has the effect of adding the
files contained in the named file to the first archive,
rather than adding the second archive as an element of the
first. Note: This option requires a rewritable tarfile,
and therefore does not work on quarter-inch cartridge
tapes.
-c
--create Create a new archive (or truncates an old one) and writes
the named files to it.
-d
--diff
--compare Find differences between files in the archive and corre-
sponding files in the file system.
--delete Delete named files from the archive (Does not work on
quarter-inch tapes).
-r
--append Append files to the end of an archive (Does not work on
quarter-inch tapes).
-t
--list List the contents of an archive; if filename arguments are
given, only those files are listed, otherwise the entire
table of contents is listed.
-u
--update Append the named files if the on-disk version has a modi-
fication date more recent than their copy in the archive
(if any). Does not work on quarter-inch tapes.
-x
--extract
--get Extract files from an archive. The owner, modification
time, and file permissions are restored, if possible. If
no file arguments are given, extract all the files in the
archive. If a filename argument matches the name of a di-
rectory on the tape, that directory and its contents are
extracted (as well as all directories under that directo-
ry). If the archive contains multiple entries correspond-
ing to the same file (see the --append command above), the
last one extracted will overwrite all earlier versions.
OPTIONS
The other options to tar may be combined arbitrarily; single-letter op-
tions may be bundled in with the command word. Verbose options which
take arguments will be followed by the argument; single-letter options
will consume successive command line arguments (see the EXAMPLES below).
--help Prints a message listing and briefly describing
all the command options to tar.
--atime-preserve Restore the access times on files which are writ-
ten to tape (note that this will change the in-
ode-change time!).
-b
--block-size number Sets the block size for reading or writing to N
512-byte blocks.
-B
--read-full-blocks Re-assemble short reads into full blocks (for
reading 4.2BSD pipes).
-C directory
--directory directory Change to directory for extraction.
--checkpoint Print directory names while reading the archive.
-f [hostname:]file
--file [hostname:]file Read or write the specified file (default is
/dev/rst0). If a hostname is specified, tar will
use rmt(8) to read or write the specified file on
a remote machine. If the given file is `-', then
tar uses stdin or stdout.
--force-local Archive file is local even if it has a colon
-F file
--info-script file
--new-volume-script file
Run a script at the end of each archive volume
(implies -M).
--fast-read Stop after all non-wildcard extraction targets
have been found in the archive.
-G
--incremental Create/list/extract old GNU-format incremental
backup.
-g file
--listed-incremental file
Create/list/extract new GNU-format incremental
backup.
-h
--dereference Don't write symlinks as symlinks; write the data
of the files they name.
-i
--ignore-zeros Ignore blocks of zeroes in archive (usually means
End-Of-File).
--ignore-failed-read Don't exit with non-zero status on unreadable
files.
-k
--keep-old-files Keep files which already exist on disk; don't
overwrite them from the archive.
-K file
--starting-file file Begin at file in the archive.
-l
--one-file-system Stay in local filesystem when creating an archive
(do not cross mount points).
-L number
--tape-length number Change tapes after writing N*1024 bytes.
-m
--modification-time Don't extract file modified time.
-M
--multi-volume Create/list/extract multi-volume archive.
-N date
--after-date date
--newer date Only store files newer than date.
--newer-mtime date Like -N, But files are selected according to
their modification time.
-o
--old-archive
--portability Write a V7 format archive, rather than POSIX for-
mat.
-O
--to-stdout Extract files to standard output.
-p
--same-permissions
--preserve-permissions Extract all protection information.
--preserve Has the effect of -p -s.
-P
--absolute-paths Don't strip leading `/'s from file names.
-R
--record-number Show record number within archive with each mes-
sage.
--remove-files Remove files after adding them to the archive.
-s
--same-order
--preserve-order List of names to extract is sorted to match
archive.
--same-owner create extracted files with the same ownership
--show-omitted-dirs Show directories which were omitted while pro-
cessing the archive.
-S
--sparse Handle "sparse" files efficiently.
-T file
--files-from file Get names of files to extract or create from
file, one per line.
--null Modifies behavior of -T to expect null-terminated
names; disables -C.
--totals Prints total bytes written with --create.
-v
--verbose Lists files written to archive with --create or
extracted with --extract; lists file protection
information along with file names with --list.
-V volume-name
--label volume-name Create archive with the given volume-name.
--version Print tar program version number.
--volno-file file File name with volume number to start with.
-w
--interactive
--confirmation Ask for confirmation for every action.
-W
--verify Attempt to verify the archive after writing it.
--exclude pattern Exclude files matching the pattern (don't extract
them, don't add them, don't list them).
-X file
--exclude-from file Exclude files listed in file.
-y
--bzip2
--unbzip2 Filter the archive through bzip2(1).
-Z
--compress
--uncompress Filter the archive through compress(1).
-z
--gzip
--gunzip Filter the archive through gzip(1).
--use-compress-program program
Filter the archive through program (which must
accept -d to mean ``decompress'').
--block-compress Block the output of compression program for tapes
or floppies (otherwise writes will be of odd
length, which device drivers may reject).
-[0-7][lmh] Specify tape drive and density.
--norecurse Don't recurse into subdirectories when creating.
--unlink Unlink files before creating them.
ENVIRONMENT
The tar program examines the following environment variables:
POSIXLY-CORRECT Normally, tar will process flag arguments that appear in
the file list. If set in the environment, this flag
causes tar to consider the first non-flag argument to
terminate flag processing, as per the POSIX specifica-
tion.
SHELL In interactive mode, a permissible response to the
prompt is to request to spawn a subshell, which will be
/bin/sh unless the SHELL variable is set.
TAPE Changes the default tape drive (which is still overrid-
den by the -f flag).
FILES
/dev/rst0 The default tape drive.
EXAMPLES
To create an archive on tape drive /dev/rst0 with a block size of 20
blocks, containing files named bert and ernie, you can enter
tar cfb /dev/rst0 20 bert ernie
or
tar --create --file /dev/rst0 --block-size 20 bert ernie
Note that the -f and -b flags both require arguments, which they take
from the command line in the order they were listed in the command word.
Because /dev/rst0 is the default device, and 20 is the default block
size, the above example could have simply been
tar c bert ernie
To extract all the C sources and headers from an archive named
backup.tar, type
tar xf backup.tar "*.[ch]"
Note that the pattern must be quoted to prevent the shell from attempting
to expand it according the files in the current working directory (the
shell does not have access to the list of files in the archive, of
course).
To copy a file hierarchy while preserving metadata, type
tar cf - -C srcdir . | tar xpf - -C destdir
To create a compressed archive on diskette, using gzip, use a command-
line like
tar --block-compress -z -c -v -f /dev/rfd1a -b 36 tar/
Note that you cannot mix bundled flags and --style flags; you can use
single-letter flags in the manner above, rather than having to type
tar --block-compress --gzip --create --verbose --file /dev/rfd1a
--block-size 36 tar/
The above-created diskette can be listed with
tar tvfbz /dev/rfd1a 36
To join two tar archives into a single archive, use
tar Af archive1.tar archive2.tar
which will add the files contained in archive2.tar onto the end of
archive1.tar (note that this can't be done by simply typing
cat archive2.tar >> archive1.tar
because of the end-of-file block at the end of a tar archive).
SEE ALSO
bzip2(1), compress(1), cpio(1), gzip(1), pax(1), symlink(7), rmt(8)
HISTORY
The tar format has a rich history, dating back to Version 6 AT&T UNIX.
The current implementation of tar is the GNU implementation, which origi-
nated as the public-domain tar written by John Gilmore.
AUTHORS
A cast of thousands, including [as listed in the ChangeLog file in the
source] John Gilmore (author of original public domain version), Jay Fen-
lason (first GNU author), Joy Kendall, Jim Kingdon, David J. MacKenzie,
Michael I. Bushnell, Noah Friedman, and innumerable others who have con-
tributed fixes and additions.
BUGS
The -C feature does not work like historical tar programs, and is proba-
bly untrustworthy.
The -A command should work to join an arbitrary number of tar archives
together, but it does not; attempting to do so leaves the end-of-archive
blocks in place for the second and subsequent archives.
NetBSD 1.6 August 6, 1994 5
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