TAR(1) General Commands Manual TAR(1)
tar - tape archiver
tar [ key ] [ name ... ]
Tar saves and restores files on magtape. Its actions are controlled by
the key argument. The key is a string of characters containing at most
one function letter and possibly one or more function modifiers. Other
arguments to the command are file 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
The function portion of the key is specified by one of the following
r The named files are written on the end of the tape. The c
function implies this.
x The named files are extracted from the tape. If the named file
matches a directory whose contents had been written onto the
tape, this directory is (recursively) extracted. The owner,
modification time, and mode are restored (if possible). If no
file argument is given, the entire content of the tape is
extracted. Note that if multiple entries specifying the same
file are on the tape, the last one overwrites all earlier.
t The names of the specified files are listed each time they
occur on the tape. If no file argument is given, all of the
names on the tape are listed.
u The named files are added to the tape if either they are not
already there or have been modified since last put on the tape.
c Create a new tape; writing begins on the beginning of the tape
instead of after the last file. This command implies r.
The following characters may be used in addition to the letter which
selects the function desired.
0,...,7 This modifier selects the drive on which the tape is mounted.
The default is 1.
v 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 name.
w causes tar to print the action to be taken followed by file
name, then wait for user confirmation. If a word beginning
with `y' is given, the action is performed. Any other input
means don't do it.
f causes tar to use the next argument as the name of the ar-
chive instead of /dev/mt?. If the name of the file is `-',
tar writes to standard output or reads from standard input,
whichever is appropriate. Thus, tar can be used as the head
or tail of a filter chain Tar can also be used to move hier-
archies with the command
cd fromdir; tar cf - . | (cd todir; tar xf -)
b causes tar to use the next argument as the blocking factor
for tape records. The default is 1, the maximum is 20. This
option should only be used with raw magnetic tape archives
(See f above). The block size is determined automatically
when reading tapes (key letters `x' and `t').
l tells tar to complain if it cannot resolve all of the links
to the files dumped. If this is not specified, no error mes-
sages are printed.
m tells tar to not restore the modification times. The mod
time will be the time of extraction.
Complaints about bad key characters and tape read/write errors.
Complaints if enough memory is not available to hold the link tables.
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 magtape driver cannot backspace raw magtape. If
the archive is on a disk file the b option should not be used at all,
as updating an archive stored in this manner can destroy it.
The current limit on file name length is 100 characters.