tar(1) DG/UX 5.4R3.00 tar(1)
NAME
tar - tape file archiver
SYNOPSIS
tar -c[vwfbLkFhienA[#]] device block tapesize incfile [file . . .]
tar -c[vwfbLkXhienA[#]] device block tapesize excfile [[-I incfile | file] . . .]
tar -r[vwfbLkFhienA[#]] device block tapesize incfile [file . . .]
tar -r[vwfbLkXhienA[#]] device block tapesize excfile [[-I incfile | file] . . .]
tar -t[vfLFien[#] device incfile [file . . .]
tar -t[vfLXien[#] device excfile [[-I incfile | file] . . .]
tar -u[vwfbLkFhienA[#]] device block tapesize incfile [file . . .]
tar -u[vwfbLkXhienA[#]] device block tapesize excfile [[-I incfile | file] . . .]
tar -x[lmovwfLFpienA[#]] device incfile [file . . .]
tar -x[lmovwfLXpienA[#]] device excfile [[-I incfile | file] . . .]
DESCRIPTION
tar saves and restores files on magnetic tape. Its actions are
controlled by a string of characters containing one function letter
(c, r, t, u, or x), and possibly followed by one or more function
modifiers (v, w, f, b, L, k, F, X, h, i, e, n, A, l, m, o, p, and #).
Other arguments to the command are files (or directory names)
specifying which files are to be dumped or restored. A filename
which follows a -I is interpreted as an include file whose contents
is a list of files or directories to be included in the file list.
In all cases, appearance of a directory name refers to the files and
(recursively) subdirectories of that directory.
The function letters are as follows:
-c Create a new tape; writing begins at the beginning of the
tape, instead of after the last file. This function letter
implies the r function letter.
-r Replace. The named files are written on the end of the tape.
The c and u function letters imply this function letter.
-t Table. The names and other information for the specified
files are listed each time they occur on the tape. The
listing is similar to the format produced by the ls -l
command [see ls(1)]. 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 function letter implies the r function
letter.
-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. If tar is invoked
as superuser, the ownership and permissions for the file are
restored. 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.
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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.
v Verbose. Normally, tar does its work silently. The v
(verbose) function modifier causes tar to echo to the screen,
the name of each file it treats, preceded by the function
letter. With the t function letter, v gives more information
about the tape entries than just the name.
w What. This causes tar to print the action to be taken,
followed by the name of the file, and then wait for your
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 function letter.
f File. This causes tar to use the device argument as the name
of the archive instead of /dev/rmt/0. 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 rather than the
default. The default blocking factor is determined as
follows: If a drive number is specified via function
modifiers 0 through 9, the default is taken from the
/etc/default/tar entry for that drive number. If an output
device is specified via the f function modifier, the default
is 32. If neither a drive number nor the f function modifier
is specified, drive number 0 is assumed and the blocking
factor is obtained from the entry for drive 0 in the
/etc/default/tar file. The maximum blocking factor is 128.
This function letter should not be supplied when operating on
regular archives or block special devices. The block size is
determined automatically when reading tapes (function letters
x and t) unless it is larger than 32. To read tapes that
contain larger records, provide the b function modifier with
a larger value.
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 function
letter.
L Follow symbolic links. This causes symbolic links to be
followed. By default, symbolic links are not followed. This
function is identical to that of the h function modifier.
k This function modifier uses the tapesize argument as the size
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in bytes per volume for non-tape devices (such as a floppy
drive). If this argument is not given, or if tapesize is 0,
multi-volume mode is disabled (the volume is assumed to be of
infinite length). This option allows you to create tar
archives which span more than one tape. For example, to
create a tar image on 150 Mbyte tapes, use a command line
similar to
tar -cvfk /dev/rmt/0 145000 dir
This function modifier may be used with the c, r, and u
function letters.
F This function modifier uses the incfile argument as a file
containing a list of named files (or directories) to be
included on the tape. This modifier can often be very
helpful for including a list of files generated by the
find(1) command. For example, if you wanted to archive the
files under the directory mydir to /dev/rmt/0 but wanted to
exclude its subdirectories, you could do so with the
following commands:
find mydir \! -type d -print >/tmp/list
tar cF /tmp/list
This function modifier may not be used with the X function
modifier; however, the -I option, which performs the same
function, is permitted with the X modifier.
X This function modifier uses the excfile argument as a file
containing a list of named files (or directories) to be
excluded, and may be used with all function letters. This
function modifier may not be used with the F function
modifier.
h This function modifier causes tar to follow symbolic links as
if they were normal files or directories. Normally tar does
not follow symbolic links. The h function modifier may be
used with the function letters c, r, and u.
p This function modifier restores the named file arguments to
their original modes, ignoring the present value returned by
umask [see umask(2)]. This option is not necessary if the
effective user ID is root. For users with root privileges,
the umask is always ignored and file modes are restored
exactly as they were recorded in the archive. This function
modifier is only useful with the x function letter.
i This function modifier causes tar to ignore directory
checksum errors.
e This function modifier causes tar to quit when certain minor
errors are encountered. Examples of "minor errors" are: a
filename that is too long, and a file that changes size while
it is being backed up. Without this modifier, tar will
continue when errors such as these are encountered.
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n This function modifier must be used when the archive is a
non-tape device (for example, a floppy drive).
A This function modifier causes absolute pathnames for files to
be suppressed, and may be used with the r, c, u, and x
function letters. This causes all pathnames to be
interpreted as relative to the current working directory.
[0-9] Digit modifiers determine the drive on which the tape is
mounted. The digit modifier tells tar to use a drive other
than the default drive. Drive numbers are mapped to actual
devices by entries in the file /etc/default/tar. In addition,
entries in /etc/default/tar specify a default record size and
default media capacity for each drive number. The format for
each entry is
archiven=device-file blocking-factor capacity
where n is the drive number, device-file is the full pathname
for the device (e.g. /dev/rmt/0), blocking-factor is the
default record size in blocks, and capacity is the media
capacity in kilobytes. If neither a digit function modifier
nor the f function modifier is specified, drive 0 is assumed
by default.
The -I option is similar in function to the F function modifier. The
argument following -I is assumed to be an include file containing a
list of named files (or directories) to be included in the archive.
Unlike the F function modifier, -I may be used with the X function
modifier; it may also be specified more than once on the command
line. The -I option and the F function modifier may not be specified
together.
FILES
/etc/default/tar
/dev/rmt/*
/tmp/tar*
DIAGNOSTICS
Complains about bad key characters and tape read/write errors.
Complains if not enough memory is available to hold the link tables.
SEE ALSO
ar(1), cpio(1), ls(1), umask(2), tar(5).
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NOTES
Tar maintains the block allocation limit of control point
directories.
Tar does not maintain the file node allocation limit of control point
directories due to limitations in the tar(5) header format.
The r and u options are not supported when writing to tape drives;
they can be used only when writing tar images to disk.
The limit on pathname length is 255 characters (155 characters for
the directory portion and 100 characters for the filename portion).
The block and seek sizes reported when verbose mode (function
modifier v) is specified are rounded to the nearest kilobyte.
CAVEATS
When creating multiple tape archives, tar will occasionally divide
the archive into completely separate tar images. In this case, it
will be necessary to execute tar more than once in order to restore
the entire archive. When this happens, tar will complete execution
before all the tapes archived have been restored. There will be no
loss of data.
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