TAR(1-SysV) RISC/os Reference Manual TAR(1-SysV)
NAME
tar - tape archiver
SYNOPSIS
tar -{rxtuc}[dopvwfbnlmhBCiFNS] [tapefile] [bsize] [list-
file] [rhost] file1 file2...
DESCRIPTION
tar saves and restores multiple files on a single file (usu-
ally a magnetic tape, but it can be any file). tar's actions
are controlled by the first argument. The first argument is
a string of characters containing at most one function
letter and possibly one or more function modifiers. Other
arguments to tar are file or directory names specifying
which files to dump or restore. In all cases, appearance of
a directory name refers to the files and (recursively) sub-
directories of that directory.
The function portion of the first argument is specified by
one of the following letters:
r The named files are written on the end of the
tape. The c function implies this. (NOTE: the r
function will not write files on the end of most
cartridge tapes and some half-inch tapes. The
nature of some devices makes it nearly impossible
to seek back over individual records, so there is
no way to find the end of the tar archive.)
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.
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The following characters may be used in addition to the
letter which selects the function desired. For options
which require an extra argument (n, f, b, and N) the extra
arguments must be in the same order as the function modif-
iers to which they correspond.
d This option causes directory entries to be placed
on the tape, which means that directory permis-
sions and ownerships are preserved. The resulting
tar archive can cause warning messages if
extracted on standard System III or System V sys-
tems, but will still work.
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 function.
p This modifier says to restore files to their ori-
ginal modes, ignoring the present umask(2).
Setuid and sticky information will also be
restored to the super-user.
0, ..., 9 This modifier selects an alternate drive on which
the tape is mounted. The default is drive 0 at
1600 bpi, which is normally /dev/rmt/m0.
v Normally tar does its work silently. The v (ver-
bose) option makes tar print the name of each file
it treats preceded by the function letter. With
the t function, the verbose option gives more
information about the tape entries than just their
names.
w tar prints the action to be taken followed by file
name, then waits for user confirmation. If a word
beginning with `y' is given, the specified action
is performed, otherwise the action is not per-
formed.
f tar uses the next argument (tapefile) as the name
of the archive instead of /dev/rmt/m?. 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 hierarchies with the command
cd fromdir; tar cf - . | (cd todir; tar xf -)
b tar uses the next argument (bsize) as the blocking
factor for tape records. The default is 20. This
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option should only be used with raw magnetic tape
archives (See f above). The block size may be
determined automatically when reading tapes (first
argument function letters `x' and `t'), but only
if the block size on the tape is no more than the
block size specified with b (or the default).
n tar uses the next argument (listfile) as the name
of a file which contains the list of file or
directory names. If the name of the file is `-',
tar reads from standard input. This option works
both for creation (option c) and for extraction
(option x).
l tells tar to complain if it cannot resolve all of
the links to the files dumped. If this is not
specified, no error messages are printed.
m tells tar not to restore the modification times.
The modification time will be the time of extrac-
tion.
h Force tar to follow symbolic links as if they were
normal files or directories. Normally, tar does
not follow symbolic links.
B Forces input and output blocking to 20 blocks per
record. This option was added so that tar can
work across a communications channel where the
blocking may not be maintained.
C If a file name is preceded by -C, then tar will
perform a chdir(2) to that file name. This allows
multiple directories not related by a close common
parent to be archived using short relative path
names. For example, to archive files from
/usr/include and from /etc, one might use
tar c -C /usr include -C / etc
i Ignore directory checksum errors. The errors are
reported, but are not fatal.
F If one F is given, all directories named ``SCCS''
and ``RCS'', and files named ``core'' and ``errs''
are ignored. If more than one F is given, files
named ``a.out'' and all files with the suffix
``.o'' are also ignored. This is useful for
creating archives of source trees.
N Use the next argument (rhost) as the name of a
remote system on which the tape will be processed.
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This remote handling is done using the remote
magtape protocol described in rmt(8C). To illus-
trate, suppose we wish to create a tar file on the
system "orac" using the device /dev/rmt/m0:
tar cfN /dev/rmt/m0 rhost directory
This feature allows systems without local tape
transports (e.g. workstations) to make use of tape
transports located elsewhere in the network.
S Archive/extract block and character special files
and FIFOs.
Previous restrictions dealing with tar's inability to prop-
erly handle blocked archives have been lifted.
FILES
/dev/rmt/m?
/tmp/tar*
SEE ALSO
tar(4)
DIAGNOSTICS
Complaints about bad first argument characters and tape
read/write errors.
Complaints if enough memory is not available to hold the
link tables.
ERRORS
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 current limit on file name length is 100 characters.
There is no way selectively to follow symbolic links.
When extracting tapes created with the r or u options,
directory modification times may not be set correctly.
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