tar [ key ] [ files ]
tar saves and restores files to and from an archive
medium; typically, this is a floppy disk, a tape, or a regular file.
The actions of tar are controlled by the key;
this is a string of characters containing at most one function
letter and possibly one or more function modifiers.
files specifies the files to be backed up or restored. If
a directory name is specified, this implies that the files and the
entire subdirectory tree of the directory are to be backed up or
for details of the restrictions imposed by the capabilities of
One of the following function letters must be specified:
Creates a new archive; writing begins at the beginning of the
archive, instead of after the last file.
Creates a new archive as above, containing compressed files. The
files to be archived should be compressed first using
When the archive is unpacked, tar will pipe the files
expanding them (if necessary). Note that this function modifier has
no effect on filenames. That is, files stored with a .Z
suffix retain them when unpacked, even if they have been
The named files are written to the end of an existing
This function letter is only valid for appending files to disk
archives. When specifying the absolute path of an archive device
with the f function modifier, use the n function
modifier to indicate that the device is not a magnetic tape.
This function letter cannot be used with tape devices.
The names of the specified files are listed each time that they
occur on the archive. If no files argument is given, all
the names on the archive are listed.
The named files are added to the archive if they are not
already there, or if they have been modified since last written on
that archive. This function letter cannot be used with tape devices.
The named files are extracted from the archive. If a named
file matches a directory whose contents had been written onto the
archive, this directory is (recursively) extracted. The owner,
modification time, and mode are restored (if possible). If no
files argument is given, the entire contents of the
archive are extracted. Note that if several files with the same name
are on the archive, the last one overwrites all earlier ones. There
is no way to ask for the nth occurrence of a file.
The following characters are used in addition to the key function
This numeric key selects the device on which the archive is
mounted. The available numeric keys are defined in the file
/etc/default/tar. A list of archive devices and their
corresponding numeric keys can be displayed by entering
tar without any arguments. The f function
modifier is used to specify an archive device which is not in
Suppresses absolute filenames by removing leading slash (/)
characters from filenames. When used with the c,
r, t and u function letters, the
A function modifier prevents leading slashes being written
to the archive headers. When used with the x function
letter to extract files, arguments must be given as pathnames
excluding the leading slash.
Causes tar to use the next argument as the blocking factor
for archive records. The blocking factor is used to calculate the
archive block size. This function modifier should only be used with
archives on raw devices (see the f function modifier for
how to select different devices).
The blocking factor is specified as a multiple of 512 bytes, from 1
(equivalent to an archive block size of 512 bytes) up to a maximum
of 20 (equivalent to 10K). If the device is not a tape
device, the blocking factor must be specified as an even number from
2 to 20.
For example, to use a 9K block size with a floppy disk, specify a
blocking factor of 18:
tar cvfb /dev/rfd0 18 file
The block size is determined automatically when reading tape
Prevents files from being split across volumes (tapes or floppy
disks). If there is not enough room on the present volume for a
given file, tar prompts for a new volume. This is only
valid when the k function modifier is also specified on
the command line.
Causes tar to use the next argument as the name of the
archive instead of the default device listed in
If the name of the file is a dash (-), 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 -)
Causes tar to use the next argument as the name of a file
from which succeeding arguments are taken.
to use the next argument as the size of an archive volume in
kilobytes (KB). The minimum value allowed is 250. Very
large files are split into ``extents'' across volumes. When
restoring from a multi-volume archive, tar only prompts
for a new volume if a split file has been partially restored. To
override the archive length value in the default file, specify 0 as
the argument to k on the command line.
Tells tar to display an error message if it cannot resolve
all of the links to the files being backed up. If l is
not specified, no error messages are displayed.
Follow symbolic links and archive the contents of the regular files
to which they ultimately point with the name of the topmost link. By
default, tar archives symbolic links without following
them unless you also specify the P function modifier.
Tells tar not to restore the modification times. The
modification time of the file is the time of extraction.
Indicates the archive device is not a magnetic tape. The k
function modifier implies this. Listing and extracting the contents
of an archive are faster because tar can seek over files
it wishes to skip. Sizes are printed in kilobytes instead of tape
Assign the user and group identifiers of the user to the files being
extracted rather than those stored on the archive. This is the
default behavior of tar. This function modifier cannot be
combined with the p function modifier.
Extract the files using their original permissions if the user is
not the super user. It is possible that the user may be unable to
extract files because of the permissions associated with the files
or directories being extracted.
The sense of this function modifier is reversed for root;
the files will be extracted with user and group ownership by
This function modifier cannot be combined with the function letter
Select the historical-compatibility mode of tar; do not
archive symbolic links, information about directories, or empty
directories. If you specify this function modifier but not the
L function modifier, tar issues a warning
message when it encounters a symbolic link, skips over the link, and
continues with the rest of the files.
During extraction causes tar to exit immediately after
each file on the command line has been extracted, rather than
continuing to look for additional files of the same name.
Truncates filenames of greater than 14 characters on extraction.
This is used for extracting files from EAFS-type
filesystems that support long filenames (up to 255 characters long)
to AFS-type filesystems that support maximum 14-character
Normally, tar does its work silently. The v
(verbose) function modifier causes tar to display the name
of each file it treats, preceded by the function letter. With the
t function, v gives more information about the
archive entries than just the name.
Causes tar to display the action to be taken, followed by
the name of the file, and then wait for the user's confirmation. If
a word beginning with ``y'' is given, the action is
performed. Any other input means ``no''.
Default archive values
If no archive device is specified, either by using a numeric key or
the f function modifier, tar looks for a line in
file /etc/default/tar beginning with the string
archive=. Following this string are 4 fields, separated by
spaces, which contain values for the device name, blocking factor,
volume size, and device type.
The blocking factor is used to calculate the archive block size; it
is expressed as a multiple of 512 bytes.
The volume size entry should be modified to reflect the size in
kilobytes of the archive volume used. Note that a volume size of `0'
indicates infinite volume length. The device type is set to
y for tape devices; otherwise, it is set to n.
For example, the following is the default device entry from
archive=/dev/rfd096ds15 10 1200 n
This indicates that the default device is a floppy disk drive,
accessed as a raw device with a blocking factor of 10 (equivalent to
5KB, or ten 512-byte disk blocks) and a volume size of
1200KB. Any default value may be overridden using the
b and k function modifiers.
When a numeric key (# in the range 0-9999) is specified, the
corresponding device attributes are read from the line beginning
with archive#= in the file /etc/default/tar. The
remainder of the line has the same format as for the default archive
device in the same file.
The default file /etc/default/tar must exist if a device
is not specified on the command line using the f function
Using absolute and relative pathnames
A critical consideration when creating a tar volume involves the use
of absolute or relative pathnames. Consider the following
tar command examples, as executed from the directory
tar cv /u/target/arrow
tar cv arrow
The first command creates a tar volume with the absolute pathname:
/u/target/arrow. The second yields a tar volume with a
relative pathname: ./arrow. (The ./ is implicit
and shown here as an example; ./ should not be specified
when retrieving the file from the archive.) When restored, the
first example results in the file arrow being written to
the directory /u/target (if it exists and you have write
permission) no matter what your working directory. The second
example simply writes the file arrow to your present
Absolute pathnames specify the location of a file in relation to the
root directory (/); relative pathnames are relative to
the current directory. This must be taken into account when making a
tar tape or disk. Backup volumes use absolute pathnames so that they
can be restored to the proper directory. Use relative pathnames when
creating a tar volume where absolute pathnames are unnecessary. If
necessary, you can specify the A function modifier to
override absolute pathnames.
tar returns a value of 0 (zero) if it completes
successfully; it returns a non-zero value if an error has occurred.
Displays an error message about bad key characters and archive
Displays an error message if not enough memory is available to hold
the link tables.
If the name of a floppy disk device is /dev/fd1, then a
tar format file can be created on this device by entering:
tar cvfk /dev/fd1 360 files
where files are the names of files you want archived and
360 is the capacity of the floppy disk in kilobytes. Note that
arguments to key letters are given in the same order as the key
letters themselves, thus the fk key letters have
corresponding arguments /dev/fd1 and 360.
To display a listing of the archive, enter:
tar tvf /dev/fd1
At some later time you may want to extract the files from the
archive floppy. You can do this by entering:
tar xvf /dev/fd1
The above command extracts all files from the archive, using the
exact same pathnames as used when the archive was created. Because
of this behavior, it is normally best to save archive files with
relative pathnames rather than absolute ones, since directory
permissions may not let you read the files into the absolute
directories specified. (See the A flag under ``Options''.)
In the above examples, the v (verbose) function modifier
is used simply to confirm the reading or writing of archive files on
the screen. Also, a regular file could be substituted for the floppy
device /dev/fd1 shown in the examples.
If the default device were to be used for the above examples, the
corresponding tar commands would be:
tar cvk 360 files
The tar commands for the device corresponding to 5 in the
device table would be:
tar cv5k 360 files
tar can be used to create archives of compressed files
that are automatically uncompressed when they are extracted. For
tar Cvf tmpZ.tar ./tmp/
All the files in ./tmp are compressed, then the archive
tmpZ.tar is created using the C function letter
(instead of c). When the archive is unpacked, the files
will automatically be uncompressed. Note that if the files that are
archived have a .Z suffix, they will be extracted to
destination files with the same name even though they are no longer
tar cannot archive device special files. For this reason,
it is not suitable for creating filesystem backups.
Prior to this release, tar could not archive symbolic
links, information about directories, or empty directories but it
could follow symbolic links if the L function modifier was
specified. Use the P function modifier to tar if
you want to create an archive that can be read by the previous
version of tar.
The limit on pathname length is 99 characters for archiving
files. tar can read ptar archives with pathnames
up to 255 characters long if specified without the P
When extracting from an archive, if several files with the same name
are on the archive, the last one overwrites all earlier ones. There
is no way to ask for the nth occurrence of a file.
Archives created with the C function letter may be
incompatible with other archivers and implementations of
tar on other systems.
Note that the u function letter can be slow.
tar does not verify the selected media type.
When archiving a directory that contains subdirectories,
tar will only access those subdirectories that are within
17 levels of nesting. Subdirectories at higher levels will be
ignored after tar displays an error message.
tar executable file
default values of device names, blocking factors, volume sizes, and
temporary work files used by tar
Open UNIX 8 compatibility notes
When running ACP on Open UNIX 8 and UnixWare 7 systems,
set OSRCMDS=on to use
the SCO OpenServer version of the <tar> command.
This provides the expected behaviors
for SCO OpenServer applications.
The SCO OpenServer version of this command
is also provided on Open UNIX 8 systems under the OSP feature
Running SCO OpenServer Applications
topic in the Open UNIX 8 documentation set.
tar is conformant with:
AT&T SVID Issue 2;
X/Open CAE Specification, Commands and Utilities, Issue 4, 1992: note that this command is marked as to be
X/Open CAE Specification, Commands and Utilities, Issue 4, Version 2, 1994.: note that this command is marked as to be
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003