683 lines
19 KiB
Groff
683 lines
19 KiB
Groff
.\" Copyright (c) 2003 Tim Kientzle
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 13, 2004
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.Dt BSDTAR 1
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.Os
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.Sh NAME
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.Nm tar
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.Nd manipulate tape archives
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.Sh SYNOPSIS
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.Nm
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.Op Ar bundled-flags Ao args Ac
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.Op Ao Ar file Ac | Ao Ar pattern Ac ...
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.Nm
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.Brq Fl c
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.Op Ar options
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.Op Ar files | directories
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.Nm
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.Brq Fl r | Fl u
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.Fl f Ar archive-file
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.Op Ar options
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.Op Ar files | directories
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.Nm
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.Brq Fl t | Fl x
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.Op Ar options
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.Op Ar patterns
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.Sh DESCRIPTION
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.Nm
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creates and manipulates streaming archive files.
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.Pp
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The first synopsis form shows a
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.Dq bundled
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option word.
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This usage is provided for compatibility with historical implementations.
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See COMPATIBILITY below for details.
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.Pp
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The other synopsis forms show the preferred usage.
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The first option to
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.Nm
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is a mode indicator from the following list:
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.Bl -tag -compact -width indent
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.It Fl c
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Create a new archive containing the specified items.
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.It Fl r
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Like
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.Fl c ,
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but new entries are appended to the archive.
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Note that this only works on uncompressed archives stored in regular files.
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The
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.Fl f
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option is required.
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.It Fl t
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List archive contents to stdout.
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.It Fl u
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Like
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.Fl r ,
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but new entries are added only if they have a modification date
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newer than the corresponding entry in the archive.
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Note that this only works on uncompressed archives stored in regular files.
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The
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.Fl f
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option is required.
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.It Fl x
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Extract to disk from the archive.
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If a file with the same name appears more than once in the archive,
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each copy will be extracted, with later copies overwriting (replacing)
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earlier copies.
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.El
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.Pp
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In
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.Fl c ,
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.Fl r ,
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or
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.Fl u
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mode, each specified file or directory is added to the
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archive in the order specified on the command line.
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By default, the contents of each directory are also archived.
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.Pp
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In extract or list mode, the entire command line
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is read and parsed before the archive is opened.
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The pathnames or patterns on the command line indicate
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which items in the archive should be processed.
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Patterns are shell-style globbing patterns as
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documented in XXXX.
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.Sh OPTIONS
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Unless specifically stated otherwise, options are applicable in
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all operating modes.
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.Bl -tag -width indent
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.It Cm @ Ns Pa archive
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(c and r mode only)
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The specified archive is opened and the entries
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in it will be appended to the current archive.
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As a simple example,
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.Dl Nm Fl c Fl f Pa - Pa newfile Cm @ Ns Pa original.tar
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writes a new archive to standard output containing a file
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.Pa newfile
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and all of the entries from
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.Pa original.tar .
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In contrast,
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.Dl Nm Fl c Fl f Pa - Pa newfile Pa original.tar
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creates a new archive with only two entries.
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Similarly,
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.Dl Nm Fl czf Pa - Fl -format Cm pax Cm @ Ns Pa -
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reads an archive from standard input (whose format will be determined
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automatically) and converts it into a gzip-compressed
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pax-format archive on stdout.
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In this way,
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.Nm
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can be used to convert archives from one format to another.
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.It Fl b Ar blocksize
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Specify the block size, in 512-byte records, for tape drive I/O.
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As a rule, this argument is only needed when reading from or writing
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to tape drives, and usually not even then as the default block size of
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20 records (10240 bytes) is very common.
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.It Fl C Ar directory
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In c and r mode, this changes the directory before adding
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the following files.
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In x mode, change directories after opening the archive
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but before extracting entries from the archive.
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.It Fl -check-links ( Fl W Cm check-links )
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(c and r modes only)
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Issue a warning message unless all links to each file are archived.
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.It Fl -exclude Ar pattern ( Fl W Cm exclude Ns = Ns Ar pattern )
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Do not process files or directories that match the
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specified pattern.
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Note that exclusions take precedence over patterns or filenames
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specified on the command line.
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.It Fl -format Ar format ( Fl W Cm format Ns = Ns Ar format )
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(c mode only)
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Use the specified format for the created archive.
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Supported formats include
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.Dq cpio ,
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.Dq pax ,
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.Dq shar ,
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and
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.Dq ustar .
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Other formats may also be supported; see
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.Xr libarchive-formats 5
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for more information about currently-supported formats.
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.It Fl f Ar file
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Read the archive from or write the archive to the specified file.
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The filename can be
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.Pa -
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for standard input or standard output.
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If not specified, the default tape device will be used.
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(On FreeBSD, the default tape device is
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.Pa /dev/sa0 . )
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.It Fl -fast-read ( Fl W Cm fast-read )
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(x and t mode only)
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Extract or list only the first archive entry that matches each pattern
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or filename operand.
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Exit as soon as each specified pattern or filename has been matched.
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By default, the archive is always read to the very end, since
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there can be multiple entries with the same name and, by convention,
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later entries overwrite earlier entries.
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This option is provided as a performance optimization.
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.It Fl H
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(c and r mode only)
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Symbolic links named on the command line will be followed; the
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target of the link will be archived, not the link itself.
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.It Fl h
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(c and r mode only)
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Synonym for
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.Fl L .
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.It Fl -include Ar pattern ( Fl W Cm include Ns = Ns Ar pattern )
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Process only files or directories that match the specified pattern.
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Note that exclusions specified with
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.Fl -exclude
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take precedence over inclusions.
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If no inclusions are explicitly specified, all entries are processed by
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default.
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The
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.Fl -include
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option is especially useful when filtering archives.
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For example, the command
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.Dl Nm Fl c Fl f Pa new.tar Fl -include='*foo*' Cm @ Ns Pa old.tgz
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creates a new archive
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.Pa new.tar
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containing only the entries from
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.Pa old.tgz
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containing the string
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.Sq foo .
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.It Fl j
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(c mode only)
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Compress the resulting archive with
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.Xr bzip2 1 .
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In extract or list modes, this option is ignored.
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Note that, unlike other
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.Nm tar
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implementations, this implementation recognizes bzip2 compression
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automatically when reading archives.
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.It Fl k
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(x mode only)
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Do not overwrite existing files.
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In particular, if a file appears more than once in an archive,
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later copies will not overwrite earlier copies.
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.It Fl L
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(c and r mode only)
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All symbolic links will be followed.
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Normally, symbolic links are archived as such.
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With this option, the target of the link will be archived instead.
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.It Fl l
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If
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.Ev POSIXLY_CORRECT
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is specified in the environment, this is a synonym for the
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.Fl -check-links
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option.
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Otherwise, an error will be displayed.
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Users who desire behavior compatible with GNU tar should use
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the
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.Fl -one-file-system
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option instead.
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.It Fl m
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(x mode only)
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Do not extract modification time.
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By default, the modification time is set to the time stored in the archive.
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.It Fl n
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(c, r, u modes only)
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Do not recursively archive the contents of directories.
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.It Fl -nodump ( Fl W Cm nodump )
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(c and r modes only)
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Honor the nodump file flag by skipping this file.
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.It Fl O
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(x, t modes only)
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In extract (-x) mode, files will be written to standard out rather than
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being extracted to disk.
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In list (-t) mode, the file listing will be written to stderr rather than
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the usual stdout.
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.It Fl o
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(x mode only)
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Use the user and group of the user running the program rather
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than those specified in the archive.
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Note that this has no significance unless
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.Fl p
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is specified, and the program is being run by the root user.
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In this case, the file modes and flags from
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the archive will be restored, but ACLs or owner information in
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the archive will be discarded.
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.It Fl P
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Preserve pathnames.
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By default, absolute pathnames (those that begin with a /
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character) have the leading slash removed both when creating archives
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and extracting from them.
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Also,
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.Nm
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will refuse to extract archive entries whose pathnames contain
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.Pa ..
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or whose target directory would be altered by a symlink.
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This option suppresses these behaviors.
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.It Fl p
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(x mode only)
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Preserve file permissions.
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Attempt to restore the full permissions, including owner, file modes, file
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flags and ACLs, if available, for each item extracted from the archive.
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By default, newly-created files are owned by the user running
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.Nm ,
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the file mode is restored for newly-created regular files, and
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all other types of entries receive default permissions.
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If
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.Nm
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is being run by root, the default is to restore the owner unless the
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.Fl o
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option is also specified.
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.It Fl T Ar filename
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(c mode only)
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Read names to be archived from
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.Pa filename .
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Names are terminated by newlines.
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The special name
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.Dq -C
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will cause the current directory to be changed to the directory
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specified on the following line.
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.It Fl U
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(x mode only)
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Unlink files before creating them.
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Without this option,
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.Nm
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overwrites existing files, which preserves existing hardlinks.
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With this option, existing hardlinks will be broken, as will any
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symlink that would affect the location of an extracted file.
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.It Fl v
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Produce verbose output.
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In create and extract modes,
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.Nm
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will list each file name as it is read from or written to
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the archive.
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In list mode,
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.Nm
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will produce output similar to that of
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.Xr ls 1 .
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Additional
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.Fl v
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options will provide additional detail.
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.It Fl W Ar longopt=value
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Long options (preceded by
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.Fl - )
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are only supported directly on systems that have the
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.Xr getopt_long 3
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function.
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The
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.Fl W
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option can be used to access long options on systems that
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do not support this function.
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.It Fl w
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Ask for confirmation for every action.
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.It Fl X Ar filename
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Read a list of exclusion patterns from the specified file.
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See
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.Fl -exclude
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for more information about the handling of exclusions.
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.It Fl y
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(c mode only)
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Compress the resulting archive with
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.Xr bzip2 1 .
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In extract or list modes, this option is ignored.
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Note that, unlike other
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.Nm tar
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implementations, this implementation recognizes bzip2 compression
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automatically when reading archives.
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.It Fl z
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(c mode only)
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Compress the resulting archive with
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.Xr gzip 1 .
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In extract or list modes, this option is ignored.
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Note that, unlike other
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.Nm tar
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implementations, this implementation recognizes gzip compression
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automatically when reading archives.
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.El
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.Sh EXAMPLES
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The following creates a new archive
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called
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.Ar file.tar
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that contains two files
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.Ar source.c
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and
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.Ar source.h :
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.Dl Nm Fl czf Pa file.tar Pa source.c Pa source.h
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.Pp
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To view a detailed table of contents for this
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archive:
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.Dl Nm Fl tvf Pa file.tar
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.Pp
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To extract all entries from the archive on
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the default tape drive:
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.Dl Nm Fl x
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.Pp
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In create mode, the list of files and directories to be archived
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can also include directory change instructions of the form
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.Cm -C Ns Pa foo/baz
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and archive inclusions of the form
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.Cm @ Ns Pa archive-file .
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For example, the command line
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.Dl Nm Fl c Fl f Pa new.tar Pa foo1 Cm @ Ns Pa old.tgz Cm -C Ns Pa /tmp Pa foo2
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will create a new archive
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.Pa new.tar .
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.Nm
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will read the file
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.Pa foo1
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from the current directory and add it to the output archive.
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It will then read each entry from
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.Pa old.tgz
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and add those entries to the output archive.
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Finally, it will switch to the
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.Pa /tmp
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directory and add
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.Pa foo2
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to the output archive.
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.Sh DIAGNOSTICS
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.Ex -std
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.Sh ENVIRONMENT
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The following environment variables affect the execution of
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.Nm :
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.Bl -tag -width ".Ev BLOCKSIZE"
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.It Ev LANG
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The locale to use.
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See
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.Xr environ 7
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for more information.
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.It Ev POSIXLY_CORRECT
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If this environment variable is defined, the
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.Fl l
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option will be interpreted in accordance with
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.St -p1003.1-96 .
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.It Ev TAPE
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The default tape device.
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The
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.Fl f
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option overrides this.
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.It Ev TZ
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The timezone to use when displaying dates.
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See
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.Xr environ 7
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for more information.
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.El
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.Sh FILES
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.Bl -tag -width ".Ev BLOCKSIZE"
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.It Pa /dev/sa0
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The default tape device, if not overridden by the
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.Ev TAPE
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environment variable or the
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.Fl f
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option.
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.El
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.Sh COMPATIBILITY
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The bundled-arguments format is supported for compatibility
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with historic implementations.
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It consists of an initial word (with no leading - character) in which
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each character indicates an option.
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Arguments follow as separate words.
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The order of the arguments must match the order
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of the corresponding characters in the bundled command word.
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For example,
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.Dl Nm Cm tbf 32 Pa file.tar
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specifies three flags
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.Cm t ,
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.Cm b ,
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and
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.Cm f .
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The
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.Cm b
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and
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.Cm f
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flags both require arguments,
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so there must be two additional items
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on the command line.
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The
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.Ar 32
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is the argument to the
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.Cm b
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flag, and
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.Ar file.tar
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is the argument to the
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.Cm f
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flag.
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.Pp
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|
The mode options c, r, t, u, and x and the options
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|
b, f, l, m, o, v, and w comply with SUSv2.
|
|
.Pp
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|
For maximum portability, scripts that invoke
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.Nm tar
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should use the bundled-argument format above, should limit
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themselves to the
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.Cm c ,
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.Cm t ,
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and
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.Cm x
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modes, and the
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.Cm b ,
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.Cm f ,
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.Cm m ,
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.Cm v ,
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and
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.Cm w
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options.
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.Pp
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|
On systems that support getopt_long(), additional long options
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|
are available to improve compatibility with other tar implementations.
|
|
.Sh SECURITY
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|
Certain security issues are common to many archiving programs, including
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|
.Nm .
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|
In particular, carefully-crafted archives can request that
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.Nm
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|
extract files to locations outside of the target directory.
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|
This can potentially be used to cause unwitting users to overwrite
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files they did not intend to overwrite.
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|
If the archive is being extracted by the superuser, any file
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on the system can potentially be overwritten.
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|
There are three ways this can happen.
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|
Although
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.Nm
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|
has mechanisms to protect against each one,
|
|
savvy users should be aware of the implications:
|
|
.Bl -bullet -width indent
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|
.It
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|
Archive entries can have absolute pathnames.
|
|
By default,
|
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.Nm
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|
removes the leading
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.Pa /
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character from filenames before restoring them to guard against this problem.
|
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.It
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|
Archive entries can have pathnames that include
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.Pa ..
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components.
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|
By default,
|
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.Nm
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|
will not extract files containing
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.Pa ..
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components in their pathname.
|
|
.It
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|
Archive entries can exploit symbolic links to restore
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files to other directories.
|
|
An archive can restore a symbolic link to another directory,
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then use that link to restore a file into that directory.
|
|
To guard against this,
|
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.Nm
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|
checks each extracted path for symlinks.
|
|
If the final path element is a symlink, it will be removed
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and replaced with the archive entry.
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|
If
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.Fl U
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is specified, any intermediate symlink will also be unconditionally removed.
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|
If neither
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.Fl U
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nor
|
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.Fl P
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|
is specified,
|
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.Nm
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|
will refuse to extract the entry.
|
|
.El
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|
To protect yourself, you should be wary of any archives that
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|
come from untrusted sources.
|
|
You should examine the contents of an archive with
|
|
.Dl Nm Fl tf Pa filename
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|
before extraction.
|
|
You should use the
|
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.Fl k
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|
option to ensure that
|
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.Nm
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|
will not overwrite any existing files or the
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.Fl U
|
|
option to remove any pre-existing files.
|
|
You should generally not extract archives while running with super-user
|
|
privileges.
|
|
Note that the
|
|
.Fl P
|
|
option to
|
|
.Nm
|
|
disables the security checks above and allows you to extract
|
|
an archive while preserving any absolute pathnames,
|
|
.Pa ..
|
|
components, or symlinks to other directories.
|
|
.Sh SEE ALSO
|
|
.Xr bzip2 1 ,
|
|
.Xr cpio 1 ,
|
|
.Xr gzip 1 ,
|
|
.Xr mt 1 ,
|
|
.Xr pax 1 ,
|
|
.Xr shar 1 ,
|
|
.Xr libarchive 3 ,
|
|
.Xr libarchive-formats 5 ,
|
|
.Xr tar 5
|
|
.Sh STANDARDS
|
|
There is no current POSIX standard for the tar command; it appeared
|
|
in
|
|
.St -p1003.1-96
|
|
but was dropped from
|
|
.St -p1003.1-2001 .
|
|
The options used by this implementation were developed by surveying a
|
|
number of existing tar implementations as well as the old POSIX specification
|
|
for tar and the current POSIX specification for pax.
|
|
.Pp
|
|
The ustar and pax interchange file formats are defined by
|
|
.St -p1003.1-2001
|
|
for the pax command.
|
|
.Sh BUGS
|
|
POSIX and GNU violently disagree about the meaning of the
|
|
.Fl l
|
|
option.
|
|
Because of the potential for disaster if someone expects
|
|
one behavior and gets the other, the
|
|
.Fl l
|
|
option is deliberately broken in this implementation.
|
|
.Pp
|
|
The
|
|
.Fl C Pa dir
|
|
option may differ from historic implementations.
|
|
.Pp
|
|
All archive output is written in correctly-sized blocks, even
|
|
if the output is being compressed.
|
|
Whether or not the last output block is padded to a full
|
|
block size varies depending on the format and the
|
|
output device.
|
|
For tar and cpio formats, the last block of output is padded
|
|
to a full block size if the output is being
|
|
written to standard output or to a character or block device such as
|
|
a tape drive.
|
|
If the output is being written to a regular file, the last block
|
|
will not be padded.
|
|
Many compressors, including
|
|
.Xr gzip 1
|
|
and
|
|
.Xr bzip2 1 ,
|
|
complain about the null padding when decompressing an archive created by
|
|
.Nm ,
|
|
although they still extract it correctly.
|
|
.Pp
|
|
The compression and decompression is implemented internally, so
|
|
there may be insignificant differences between the compressed output
|
|
generated by
|
|
.Dl Nm Fl czf Pa - file
|
|
and that generated by
|
|
.Dl Nm Fl cf Pa - file | Nm gzip
|
|
.Pp
|
|
The default should be to read and write archives to the standard I/O paths,
|
|
but tradition (and POSIX) dictates otherwise.
|
|
.Pp
|
|
The
|
|
.Cm r
|
|
and
|
|
.Cm u
|
|
modes require that the archive be uncompressed
|
|
and located in a regular file on disk.
|
|
Other archives can be modified using
|
|
.Cm c
|
|
mode with the
|
|
.Pa @archive-file
|
|
extension.
|
|
.Pp
|
|
To archive a file called
|
|
.Pa @foo
|
|
or
|
|
.Pa -foo
|
|
you must specify it as
|
|
.Pa ./@foo
|
|
or
|
|
.Pa ./-foo ,
|
|
respectively.
|
|
.Pp
|
|
In create mode, a leading
|
|
.Pa ./
|
|
is always removed.
|
|
A leading
|
|
.Pa /
|
|
is stripped unless the
|
|
.Fl P
|
|
option is specified.
|
|
.Pp
|
|
There needs to be better support for file selection on both create
|
|
and extract.
|
|
.Pp
|
|
There is not yet any support for multi-volume archives or for archiving
|
|
sparse files.
|
|
.Pp
|
|
Converting between dissimilar archive formats (such as tar and cpio) using the
|
|
.Cm @ Ns Pa -
|
|
convention can cause hard link information to be lost.
|
|
(This is a consequence of the incompatible ways that different archive
|
|
formats store hardlink information.)
|
|
.Pp
|
|
There are alternative long options for many of the short options that
|
|
are deliberately not documented.
|
|
.Sh HISTORY
|
|
A
|
|
.Nm tar
|
|
command appeared in Seventh Edition Unix.
|
|
There have been numerous other implementations,
|
|
many of which extended the file format.
|
|
John Gilmore's
|
|
.Nm pdtar
|
|
public-domain implementation (circa November, 1987)
|
|
was quite influential, and formed the basis of GNU tar.
|
|
GNU tar was included as the standard system tar
|
|
in FreeBSD beginning with FreeBSD 1.0.
|
|
.Pp
|
|
This is a complete re-implementation based on the
|
|
.Xr libarchive 3
|
|
library.
|