TAR(1) (Cartridge Tape Utilities) TAR(1)
NAME
tar - tape file archiver
SYNOPSIS
/etc/tar -c[iLvwfb[#s]] device block files ...
/etc/tar -r[iLvwb[#s]] device block [files ...]
/etc/tar -t[iLvf[#s] device
/etc/tar -u[iLvwb[#s]] device block [files ...]
/etc/tar -x[iLlmovwf[#s]] device [files ...]
DESCRIPTION
tar saves and restores files on magnetic tape. Its actions
are controlled by the key argument. The key is a string of
characters containing one function letter (c, r, t, u, or x)
and possibly followed by one or more function modifiers (b,
f, i, L, v, w, and #). Other arguments to the command are
files (or directory names) specifying which files are to be
dumped or restored. In all cases, appearance of a directory
name refers to the files and (recursively) subdirectories of
that directory.
The function portion of the key is specified by one of the
following letters:
r Replace. The named files are written on the end of
the tape. The c function implies this function.
x Extract. The named files are extracted from the
tape. If a named file matches a directory whose
contents had been written onto the tape, this
directory is (recursively) extracted. Use the file
or directory's relative path when appropriate, or
tar will not find a match. The owner, modification
time, and mode are restored (if possible). If no
files argument is given, the entire content of the
tape is extracted. Note that if several files with
the same name are on the tape, the last one
overwrites all earlier ones.
t Table. The names and other information for the
specified files are listed each time that they occur
on the tape. The listing is similar to the format
Page 1 May 1989
TAR(1) (Cartridge Tape Utilities) TAR(1)
produced by the ls -l command. If no files argument
is given, all the names on the tape are listed.
u Update. The named files are added to the tape if
they are not already there, or have been modified
since last written on that tape. This key implies
the r key.
c Create a new tape; writing begins at the beginning
of the tape, instead of after the last file. This
key implies the r key.
The characters below may be used in addition to the letter
that selects the desired function. Use them in the order
shown in the synopsis.
i This modifier causes tar to ignore symbolic links.
L This modifier causes tar to follow symbolic links.
The default is not to follow links. If an archive is
made from a tree containing symbolic links, it will
record the path associated with each link. When it
is restored, the symbolic links will be re-made. If
-L is specified, the actual file pointed to by the
link is archived instead of the symbolic link
contents.
#s This modifier determines the drive on which the tape
is mounted (replace # with the drive number) and the
speed of the drive (replace s with l, m, or h for
low, medium or high). The modifier tells tar to use
a drive other than the default drive, or the drive
specified with the -f option. For example, with the
5h modifier, tar would use /dev/mt/5h or /dev/mt0
instead of the default drives /dev/mt/0m or
/dev/mt0, respectively. However, if for example, "-f
/dev/rmt0 5h" appeared on the command line, tar
would use /dev/rmt5h or /devmt0. The default entry
is 0m.
v Verbose. Normally, tar does its work silently. The
v (verbose) option causes it to type the name of
each file it treats, preceded by the function
letter. With the t function, v gives more
information about the tape entries than just the
Page 2 May 1989
TAR(1) (Cartridge Tape Utilities) TAR(1)
name.
w What. This causes tar to print the action to be
taken, followed by the name of the file, and then
wait for the user's confirmation. If a word
beginning with y is given, the action is performed.
Any other input means ``no''. This is not valid
with the t key.
f File. This causes tar to use the device argument as
the name of the archive instead of /dev/rmt/ctape.
(Note: the cartridge tape in UniSoft UNIX System V
is referenced as /dev/rmt/ctape.) If the name of
the file is -, tar writes to the standard output or
reads from the standard input, whichever is
appropriate. Thus, tar can be used as the head or
tail of a pipeline. tar can also be used to move
hierarchies with the command:
cd fromdir; tar cf - . | (cd todir; tar xf -)
b Blocking Factor. This causes tar to use the block
argument as the blocking factor for tape records.
The default is 1, the maximum is 20. This function
should not be supplied when operating on regular
archives or block special devices. It is mandatory
however, when reading archives on raw magnetic tape
archives (see f above). The block size is
determined automatically when reading tapes created
on block special devices (key letters x and t).
l Link. This tells tar to complain if it cannot
resolve all of the links to the files being dumped.
If l is not specified, no error messages are
printed.
m Modify. This tells tar to not restore the
modification times. The modification time of the
file will be the time of extraction.
o Ownership. This causes extracted files to take on
the user and group identifier of the user running
the program, rather than those on tape. This is
only valid with the x key.
Page 3 May 1989
TAR(1) (Cartridge Tape Utilities) TAR(1)
FILES
/dev/mt/*
/tmp/tar*
/dev/rmt/*
SEE ALSO
ar(1), cpio(1), ls(1).
DIAGNOSTICS
Complaints about bad key characters and tape read/write
errors.
Complaints if enough memory is not available to hold the
link tables.
BUGS
There is no way to ask for the n-th occurrence of a file.
Tape errors are handled ungracefully.
The u option can be slow.
The b option should not be used with archives that are going
to be updated. The current magnetic tape driver cannot
backspace raw magnetic tape. If the archive is on a disk
file, the b option should not be used at all, because
updating an archive stored on disk can destroy it.
The current limit on file name length is 100 characters.
tar doesn't copy empty directories or special files.
Page 4 May 1989