.\"
.\" Copyright (c) 1996 SigmaSoft, Th. Lockert
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by SigmaSoft, Th. Lockert.
.\" 4. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $OpenBSD: tar.1,v 1.13 1997/05/29 15:47:19 millert Exp $
.\"
.Dd June 11, 1996
.Dt TAR 1
.Os
.Sh NAME
.Nm tar
.Nd tape archiver
.Sh SYNOPSIS
.Nm
.No [-]{crtux}[befhmopvwzHLPXZ014578]
.Op Ar archive
.Op Ar blocksize
.\" XXX how to do this right?
.No [-C
.Ar directory
.No ]
.No [-s
.Ar replstr
.No ]
.Ar file1
.Op Ar file2...
.Sh DESCRIPTION
The
.Nm
command creates, adds files to, or extracts files from an
archive file in \*Qtar\*U format. A tar archive is often
stored on a magnetic tape, but can be a floppy or a regular
disk file.
.Pp
One of the following flags must be present:
.Bl -tag -width Ar
.It Fl c
Create new archive, or overwrite an existing archive,
adding the specified files to it.
.It Fl r
Append the named new files to existing archive. Note that
this will only work on media on which an end-of-file mark
can be overwritten.
.It Fl t
List contents of archive. If any files are named on the
command line, only those files will be listed.
.It Fl u
Alias for
.Fl r
.It Fl x
Extract files from archive. If any files are named on the
command line, only those files will be extracted from the
archive. If more than one copy of a file exists in the
archive, later copies will overwrite earlier copies during
extration.
.El
.Pp
In addition to the flags mentioned above, any of the following
flags may be used:
.Bl -tag -width Ar
.It Fl b Ar "blocking factor"
Set blocking factor to use for the archive,
.Nm
uses 512 byte blocks. The default is 20, the maximum is 126.
Archives with a blocking factor larger 63 violate the
.Tn POSIX
standard and will not be portable to all systems.
.It Fl e
Stop after first error.
.It Fl f Ar archive
Filename where the archive is stored. Defaults to
.Pa /dev/rst0
.It Fl h
Follow symbolic links as if they were normal files
or directories.
.It Fl m
Do not preserve modification time.
.It Fl O
Write old-style (non-POSIX) archives.
.It Fl o
Don't write directory information that the older (V7) style
.Nm
is unable to decode.
This implies the
.Fl O
flag.
.It Fl p
Preserve user id, group id, file mode, access and modification
times if possible. The user id and group id will only be set
if the user is the superuser (unless these values correspond
to the user's user and group ids).
.It Fl s Ar replstr
Modify the file or archive member names specified by the
.Ar pattern
or
.Ar file
operands according to the substitution expression
.Ar replstr ,
using the syntax of the
.Xr ed 1
utility regular expressions.
The format of these regular expressions are:
.Dl /old/new/[gp]
As in
.Xr ed 1 ,
.Cm old
is a basic regular expression and
.Cm new
can contain an ampersand (&), \\n (where n is a digit) back-references,
or subexpression matching.
The
.Cm old
string may also contain
.Dv <newline>
characters.
Any non-null character can be used as a delimiter (/ is shown here).
Multiple
.Fl s
expressions can be specified.
The expressions are applied in the order they are specified on the
command line, terminating with the first successful substitution.
The optional trailing
.Cm g
continues to apply the substitution expression to the pathname substring
which starts with the first character following the end of the last successful
substitution. The first unsuccessful substitution stops the operation of the
.Cm g
option.
The optional trailing
.Cm p
will cause the final result of a successful substitution to be written to
.Dv standard error
in the following format:
.Dl <original pathname> >> <new pathname>
File or archive member names that substitute to the empty string
are not selected and will be skipped.
.It Fl v
Verbose operation mode.
.It Fl w
Interactively rename files. This option causes
.Nm
to prompt the user for the filename to use when storing or
extracting files in an archive.
.It Fl z
Compress archive using gzip.
.It Fl C Ar directory
This is a positional argument which sets the working directory for the
following files. When extracting, files will be extracted into
the specified directory; when creating, the specified files will be matched
from the directory.
.It Fl H
Follow symlinks given on command line only.
.It Fl L
Follow all symlinks.
.It Fl P
Do not strip leading slashes (``/'') from pathnames.
The default is to strip leading slashes.
.It Fl X
Do not cross mount points in the file system.
.It Fl Z
Compress archive using compress.
.El
.Pp
The options
.Op Fl 014578
can be used to select one of the compiled-in backup devices,
.Pa /dev/rstN .
.Sh FILES
.Bl -tag -width "/dev/rst0"
.It Pa /dev/rst0
The default archive name
.El
.Sh SEE ALSO
.Xr pax 1 ,
.Xr cpio 1
.Sh AUTHOR
Keith Muller at the University of California, San Diego
.Sh ERRORS
.Nm
will exit with one of the following values:
.Bl -tag -width 2n
.It 0
All files were processed successfully.
.It 1
An error occured.
.El
.Pp
Whenever
.Nm
cannot create a file or a link when extracting an archive or cannot
find a file while writing an archive, or cannot preserve the user
ID, group ID, file mode or access and modification times when the
.Fl p
options is specified, a diagnostic message is written to standard
error and a non-zero exit value will be returned, but processing
will continue. In the case where
.Nm
cannot create a link to a file,
.Nm
will not create a second copy of the file.
.Pp
If the extraction of a file from an archive is prematurely terminated
by a signal or error,
.Nm
may have only partially extracted the file the user wanted.
Additionally, the file modes of extracted files and directories may
have incorrect file bits, and the modification and access times may
be wrong.
.Pp
If the creation of an archive is prematurely terminated by a signal
or error,
.Nm
may have only partially created the archive which may violate the
specific archive format specification.