TAR(1) COMMAND REFERENCE TAR(1)
NAME
tar - tape archiver
SYNOPSIS
tar key [ tapefilename ] [ blocksize ] [ name ... ]
DESCRIPTION
Tar saves and restores multiple files on a single file
(usually a magnetic tape, but it can be any file). Tar's
actions are controlled by the key argument. The key
consists of one (or possibly two) "function" letter(s) and
possibly one or more function modifiers. These are listed
in the OPTIONS section. The key may be preceded by a dash
(-), but this is optional.
The tapefilename argument is given with the f option. If
this is a dash (-), standard input or standard output is
used for input or output. The blocksize argument is given
only if the b option is given.
The name arguments are the names of the files and
directories to be archived. The names may be preceded by a
-C, which specifies that tar is to chdir(2) (change
directories) to that directory name (this is useful when the
directories to be archived do not have a close common parent
and it is undesirable to save a large directory structure).
All arguments following that name until the next -C is taken
to be relative to that name. The name following the -C is
not archived. If the name begins with a slash (/), tar also
does a chdir to the directory, but only to archive that
directory. After that, the current directory is changed
back to what it was before.
Directories are recursively archived, meaning that the
contents of the directory, its subdirectories, and so forth
are all archived.
Previous restrictions dealing with tar's inability to
properly handle blocked devices have been lifted.
OPTIONS
The function portion of the key is specified by one of the
following letters (Exception: both c and r may be given,
since c implies r) :
c Create a new tape; writing begins on the beginning of
the tape instead of after the last file. This command
implies r.
r The named files are written on the end of the tape. The
c function implies this. (NOTE: Some streaming tape
drives cannot support this function. In this case, an
Printed 10/17/86 1
TAR(1) COMMAND REFERENCE TAR(1)
error message will be printed to this effect.)
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. (NOTE: Some streaming tape drives can not
support this function. In this case, an error message
will be printed to this effect.)
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.
The following are function modifiers:
b Tar uses the next argument as the number of 512 byte
blocks to use for tape records. The default is 20.
This option should only be used with raw magnetic tape
archives (See f below). The block size is determined
automatically when reading tapes (function letters x and
t).
f Tar uses the next argument as the name of the archive
instead of /dev/rmt?. If the name of the file is a dash
(-), 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 -)
h Force tar to follow symbolic links as if they were
normal files or directories. Normally, tar does not
follow symbolic links.
i Tar stores a checksum for each directory in order to
check for read/write errors and corrupted tapes.
Normally, a checksum error will cause tar to terminate.
The i option tells tar to ignore directory checksum
errors. These files will be ignored.
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.
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TAR(1) COMMAND REFERENCE TAR(1)
m Tells tar not to restore the modification times. The
modification time will be the time of extraction.
o On output, tar normally places information specifying
owner and modes of directories in the archive. Former
versions of tar, when encountering this information will
give error message of the form
<name>/: cannot create.
This option will suppress the directory information.
p This option says to restore files to their original
modes, ignoring the present umask(2). Setuid and sticky
information will also be restored to the superuser.
v Normally tar does its work silently. The v (verbose)
option makes tar print the name of each file it treats
preceded by the function letter (in the case of c and r,
the letter a says that the file was added, and r says
that the file was replaced). With the t function, the
verbose option gives more information about the tape
entries than just their names. All information is
printed on the standard error, so redirection of output
must take this into account.
w Tar prints the action to be taken followed by filename,
then waits for user confirmation. If a word beginning
with y is given, the action is done. Any other input
means don't do it.
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 block may not
be maintained.
F If given once, any directories named SCCS or RCS and any
files named core or errs are ignored. If given twice,
any files named a.out or having the suffix .o are also
ignored.
T Take list of filenames and -C commands from standard
input.
W Like w, but produces a very terse description of the
action to be taken.
0, ..., 9
This modifier selects an alternate drive on which the
tape is mounted. The default is /dev/rmt8.
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TAR(1) COMMAND REFERENCE TAR(1)
EXAMPLES
To archive files from /usr/include and from /etc, you might
use one of the following:
tar c -C /usr include -C / etc
tar c /usr/include /etc
To archive all files in a directory, you could use the
following:
find . -print | tar Tc
FILES
/dev/rmt8 The default input/output archive
file.
/tmp/tar* Temporary file for the u function.
CAVEATS
The r and u functions may not be available with some tape
drives, such as streaming tape drives.
In order to keep streaming tapes streaming, it is
recommended that a blocking factor (for the b modifier) of
256 be given. This will cause tar to buffer the data in 128
kbyte blocks.
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. If
longer file names are required and portability to other UNIX
systems is not required, see cpio(1).
There is no way to selectively follow symbolic links.
SEE ALSO
ar(1), cpio(1), cpio(5), tar(5), dump(8), restore(8).
Printed 10/17/86 4
%%index%%
na:72,55;
sy:127,189;
de:316,1955;
op:2271,595;3010,2841;5995,2507;
ex:8646,373;
fi:9019,236;
ca:9255,793;
se:10048,175;
%%index%%000000000154