4BSD/usr/man/cat1/tar.1
TAR(1) UNIX Programmer's Manual TAR(1)
NAME
tar - tape archiver
SYNOPSIS
tar [ key ] [ name ... ]
DESCRIPTION
_T_a_r saves and restores files on magtape. Its actions are
controlled by the _k_e_y argument. The _k_e_y is a string of
characters containing at most one function letter and possi-
bly one or more function modifiers. Other arguments to the
command are file 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) sub-
directories of that directory.
The function portion of the key is specified by one of the
following letters:
r The named files are written on the end of the tape.
The c function implies this. Currently, this option
does not work without the c option.
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 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.
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.
c Create a new tape; writing begins on the beginning
of the tape instead of after the last file. This
command implies r.
o On output, tar normally places information specify-
ing 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.
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TAR(1) UNIX Programmer's Manual TAR(1)
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
super-user.
The following characters may be used in addition to the
letter which selects the function desired.
0,...,7 This modifier selects the drive on which the tape
is mounted. The default is 1.
v Normally _t_a_r does its work silently. The v (ver-
bose) option causes it to type the name of each
file it treats preceded by the function letter.
With the t function, v gives more information
about the tape entries than just the name.
w causes _t_a_r to print the action to be taken fol-
lowed by file name, then wait for user confirma-
tion. If a word beginning with `y' is given, the
action is performed. Any other input means don't
do it.
f causes _t_a_r to use the next argument as the name of
the archive instead of /dev/mt?. If the name of
the file is `-', tar writes to standard output or
reads from standard input, whichever is appropri-
ate. Thus, _t_a_r can be used as the head or tail of
a filter chain _T_a_r can also be used to move
hierarchies with the command
cd fromdir; tar cf - . | (cd todir; tar xf -)
b causes _t_a_r to use the next argument as the block-
ing factor for tape records. The default is 1, the
maximum is 20. This option should only be used
with raw magnetic tape archives (See f above).
l tells _t_a_r to complain if it cannot resolve all of
the links to the files dumped. If this is not
specified, no error meesages are printed.
FILES
/dev/rmt?
/tmp/tar*
DIAGNOSTICS
Complaints about bad key characters and tape read/write
errors.
Complaints if enough memory is not available to hold the
link tables.
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TAR(1) UNIX Programmer's Manual TAR(1)
BUGS
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 magtape driver cannot backspace
raw magtape. If the archive is on a disk file the b option
should not be used at all, as updating an archive stored in
this manner can destroy it.
The current limit on file name length is 100 characters.
The u option will only work with archives on disk files,
because tar now must use the raw tape mechanism.
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