TAR(1) DOMAIN/IX SYS5 TAR(1)
NAME
tar - tape (and general purpose) archiver
USAGE
tar key [ blocksize ] [ name ] files
DESCRIPTION
Tar is a general-purpose archiving utility that
⊕ bundles multiple files into a single archive file,
⊕ restores to the file system any or all of the files
in this archive,
⊕ optionally changes permissions on the files.
While tar is most often used to archive files on magnetic
tape, it can also be used any time you need to bundle a
number of files into one object for later reconstitution.
The key is a string of characters containing one function
letter and optional function modifiers. It controls what
tar does with the files to be bundled or unbundled
(restored). Note that in both cases (archiving and restor-
ing), use of a directory name as one of the files includes
all files in that directory and any subdirectories it con-
tains.
FUNCTIONS
Archiving Files
The following key letters specify tar options associated
with creating an archive file. Unless otherwise specified
(see OPTIONS below), the archive is written to the device
file /dev/mt/0m.
c Create a new archive. Writing begins at the beginning
of the file.
r Append to an archive file. Writing begins at the end
the file. (Not supported by Apollo tape drivers.)
u Add the named files to the archive only if they are not
already there, or are there but have been modified since
they were last archived. (Not supported by Apollo tape
drivers.)
Restoring Files
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The following key letters specify tar options associated
with restoration of selected files from a tar archive file.
Unless otherwise specified, the archive from which files are
restored is the device file /dev/rmt/0m. Restored files are
always written to the current directory.
t List the names of all the files in the archive.
x Extract the named files from the archive. If one of the
files is a directory, tar extracts the directory and all
files and subdirectories it contains. If no files are
specified, tar x extracts the entire contents of the
archive. Note that if several files with the same name
are in the archive, the last one overwrites all earlier
ones.
OPTIONS
You may append one or more of the following characters to
the function letter in the key.
0-9d
This option, valid only when writing archives to tape,
specifies the tape drive on which the archive is mounted
and, optionally, the density (I) of the tape as l (low),
m (medium), or h high. The default is drive 0, normally
/dev/rmt/0m.
b Set blocksize. This option is valid only when writing
archives to tape. Use of this option when writing an
archive on a disk file may destroy the archive. If the
b option is present on the tar command line, the key
must be followed by a space and an integer blocksize in
the range 1-20. This blocksize specifies the block
length for tape records. The default is 1, the maximum
is 20. Any blocksize you specify must coincide with the
block length in the magtape descriptor file for the dev-
ice to which tar is writing the archive. When tar is
reading tapes (keyletters x or t), it determines the
blocksize automatically. If the f option is also
present in the key, tar expects the name and blocksize
arguments to occur in the same order as the f and b
options. (See examples.)
f If the f option is present on the tar command line, the
key must be followed by a space and the name of the
archive you want tar to read from or write to. If this
option is omitted, the default archive is /dev/rmt/0m.
If name is given as a dash (-), tar writes to the stan-
dard output or reads from the standard input, as
appropriate. If the b option is also present in the
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key, tar expects the name and blocksize arguments to
occur in the same order as the f and b options. (See
examples.)
o Preserve ownership and permissions of restored files.
l Complain when a link to the file being archived cannot
be resolved.
m Do not restore the modification times. Modification
time of all restored files is set to the time at which
they are restored.
v Be verbose. This option makes tar display the name of
each file it archives or restores, preceded by a func-
tion letter that indicates what it is doing (or planning
to do) with the file. These function letters are a for
``append to archive'' and x for ``extract from
archive.'' When combined with the t function, v makes
tar print out a ``long'' listing for each file in the
archive, rather than just the name.
w This option makes tar display the action (see v above)
it is about to take and the name of the file that will
be affected, then wait for confirmation. If you enter a
word beginning with y, tar performs the specified
action. Any other input means ``no''.
EXAMPLES
tar cf /dev/rmt/0m /usr/you
Writes the contents of /usr/you
and all of its subdirectories to
/dev/rmt/0m (medium density
magtape).
tar xf /dev/rmt/0m Restores all of the files from
/dev/rmt/0m to the filesystem,
writing them into the current
working directory. The person
running tar is made owner of the
restored files.
tar xfo /dev/rmt/0m Restores all of the files from
/dev/rmt/0m to the filesystem,
writing them into the current
working directory. File owner-
ship is preserved as archived.
tar cf /tarfile /usr/you/src/*.c
Bundles all files in /usr/you/src
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whose names end in ``.c'' into
/tarfile.
NOTES
Since the Apollo magnetic and cartridge tape drivers do not
support the u and r functions, tar can only create new
archives (tar c) if you're writing to tape. The block
length is fixed at 10240 bytes for the files /dev/rmt8 and
/dev/rmt12, 512 bytes for the files /dev/rct8 and
/dev/rct12, and 5120 bytes for the files in /dev/mt/* and
/dev/rmt/*. If you need to change the block length, use the
/com/edmtdesc (edit magtape descriptor) command.
If need to re-tension rewind the tape, use the command
/com/rbak with the -reten (re-tension) or -rewind (rewind)
option.
Tar limits filename length to 100 characters, a limit which
may affect recursive descent into deep hierarchies.
FILES
/dev/rmt[8 | /0l] low density magtape, rewind on
file close
/dev/rmt[12 | /0ln] low density magtape, no rewind on
file close
/dev/rmt/0m medium density magtape, rewind on
file close
/dev/rmt/0mn medium density magtape, no rewind
on file close
/dev/rct[8 | /c0d0h] cartridge tape, rewind on file
close
/dev/rct[12 | /c0d0hn] cartridge tape, no rewind on file
close
/dev/rct/rfl0a floppy file name
/tmp/tar* temporary file
DIAGNOSTICS
Tar issues various complaints about bad key characters and
tape read/write errors.
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RELATED INFORMATION
intro(7), /com/rbak, /com/edmtdesc
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