TAR(1) RISC/os Reference Manual TAR(1)
NAME
tar - tape file archiver
SYNOPSIS
/usr/bin/tar -c[vwfbL[#]] device block files ...
/usr/bin/tar -r[vwfbL[#]] device block files ...
/usr/bin/tar -t[vfL[#] device [files ...]
/usr/bin/tar -u[vwfbL[#]] device block files ...
/usr/bin/tar -x[lmovwfL[#]] device [files ...]
DESCRIPTION
tar saves and restores files on magnetic tape. Its actions
are controlled by the key argument. The key is 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, and #). Other arguments to the command are files
(or directory names) specifying which files are to be dumped
or restored. In all cases, appearance of a directory name
refers to the files and (recursively) subdirectories of that
directory.
The function portion of the key is specified by one of the
following letters:
c Create a new tape; writing begins at the beginning
of the tape, instead of after the last file. This
key implies the r key.
r Replace. The named files are written on the end of
the tape. The c and u functions imply this func-
tion.
t Table. The names and other information for the
specified files are listed each time that they occur
on the tape. The listing is similar to the format
produced by the ls -l command. 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 key implies
the r key.
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 direc-
tory is (recursively) extracted. Use the file or
directory's relative path when appropriate, or tar
will not find a match. The owner, modification
time, and mode are restored (if possible). 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.
# This modifier determines the drive on which the tape
is mounted (replace # with the drive number). The
modifier tells tar to use a drive other than the
default drive, or the drive specified with the f
option. For example, with the 5h modifier, tar
would use the sixth entry from /etc/default/tar
instead of the default drives /dev/rmt/m0 . However,
if for example, -f /dev/rmt/h4 appeared on the com-
mand line, tar would use /dev/rmt/h4 The default
entry is /dev/rmt/m0.
v Verbose. Normally, tar does its work silently. The
v (verbose) option causes it to type the name of
each file it treats, preceded by the function
letter. With the t function, v gives more informa-
tion 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 the user's confirmation. If a word begin-
ning with y is given, the action is performed. Any
other input means no. This is not valid with the t
key.
f File. This causes tar to use the device argument as
the name of the archive instead of /dev/mt/0m or
/dev/mt0. 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.
The default is 1, the maximum is 20. This function
should not be supplied when operating on regular
archives or block special devices. It is mandatory
however, when reading archives on raw magnetic tape
archives (see f above). The block size is deter-
mined automatically when reading tapes created on
block special devices (key letters x and t).
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 modifica-
tion times. The modification time of the file will
be the time of extraction.
o Ownership. This causes extracted files to take on
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TAR(1) RISC/os Reference Manual TAR(1)
the user and group identifier of the user running
the program, rather than those on tape. This is
only valid with the x key.
L Follow symbolic links. This causes symbolic links
to be followed. By default, symbolic links are not
followed.
FILES
/dev/rmt/m0
/dev/rmt/m4
/dev/rmt/ctape0
/dev/rmt/ctape4
/etc/default/tar
SEE ALSO
ar(1), cpio(1), ls(1).
DIAGNOSTICS
Complaints about bad key characters and tape read/write
errors.
Complaints if enough memory is not available to hold the
link tables.
NOTES
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 b option should not be used with archives that are going
to be updated. The current magnetic tape driver cannot
backspace raw magnetic tape. If the archive is on a disk
file, the b option should not be used at all, because updat-
ing an archive stored on disk can destroy it.
The current limit on file name length is 100 characters.
tar doesn't copy empty directories or special files.
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