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<p><i>TAR</i>(1) General Commands Manual <i>TAR</i>(1)</p>

<p style="margin-top: 1em"><b>NAME</b></p>

<p style="margin-left:9%;">tar &mdash; manipulate tape
archives</p>

<p style="margin-top: 1em"><b>SYNOPSIS</b></p>

<p style="margin-left:14%;"><b>tar</b>
[<i>bundled-flags&nbsp;</i>&lang;</p>

<p>args &rang; ] [&lang; <i><br>
file</i> &rang; &nbsp;|&nbsp;&lang; <i><br>
pattern</i> &rang; &nbsp;...]</p>

<p style="margin-left:14%;"><b>tar</b> {<b>-c</b>}
[<i>options</i>]
[<i>files&nbsp;</i>|&nbsp;<i>directories</i>] <b><br>
tar</b> {<b>-r&nbsp;</b>|&nbsp;<b>-u</b>} <b>-f</b>
<i>archive-file</i> [<i>options</i>]
[<i>files&nbsp;</i>|&nbsp;<i>directories</i>] <b><br>
tar</b> {<b>-t&nbsp;</b>|&nbsp;<b>-x</b>} [<i>options</i>]
[<i>patterns</i>]</p>

<p style="margin-top: 1em"><b>DESCRIPTION</b></p>

<p style="margin-left:9%;"><b>tar</b> creates and
manipulates streaming archive files. This implementation can
extract from tar, pax, cpio, zip, jar, ar, xar, rar, rpm,
7-zip, and ISO 9660 cdrom images and can create tar, pax,
cpio, ar, zip, 7-zip, and shar archives.</p>

<p style="margin-left:9%; margin-top: 1em">The first
synopsis form shows a &ldquo;bundled&rdquo; option word.
This usage is provided for compatibility with historical
implementations. See &ldquo;COMPATIBILITY&rdquo; below for
details.</p>

<p style="margin-left:9%; margin-top: 1em">The other
synopsis forms show the preferred usage. The first option to
<b>tar</b> is a mode indicator from the following list:</p>

<p style="margin-top: 1em"><b>-c</b></p>

<p style="margin-left:19%; margin-top: 1em">Create a new
archive containing the specified items. The long option form
is <b>--create</b>.</p>

<p><b>-r</b></p>

<p style="margin-left:19%; margin-top: 1em">Like <b>-c</b>,
but new entries are appended to the archive. Note that this
only works on uncompressed archives stored in regular files.
The <b>-f</b> option is required. The long option form is
<b>--append</b>.</p>

<p><b>-t</b></p>

<p style="margin-left:19%; margin-top: 1em">List archive
contents to stdout. The long option form is
<b>--list</b>.</p>

<p><b>-u</b></p>

<p style="margin-left:19%; margin-top: 1em">Like <b>-r</b>,
but new entries are added only if they have a modification
date newer than the corresponding entry in the archive. Note
that this only works on uncompressed archives stored in
regular files. The <b>-f</b> option is required. The long
form is <b>--update</b>.</p>

<p><b>-x</b></p>

<p style="margin-left:19%; margin-top: 1em">Extract to disk
from the archive. If a file with the same name appears more
than once in the archive, each copy will be extracted, with
later copies overwriting (replacing) earlier copies. The
long option form is <b>--extract</b>.</p>

<p style="margin-left:9%; margin-top: 1em">In <b>-c</b>,
<b>-r</b>, or <b>-u</b> mode, each specified file or
directory is added to the archive in the order specified on
the command line. By default, the contents of each directory
are also archived.</p>

<p style="margin-left:9%; margin-top: 1em">In extract or
list mode, the entire command line is read and parsed before
the archive is opened. The pathnames or patterns on the
command line indicate which items in the archive should be
processed. Patterns are shell-style globbing patterns as
documented in <i>tcsh</i>(1).</p>

<p style="margin-top: 1em"><b>OPTIONS</b></p>

<p style="margin-left:9%;">Unless specifically stated
otherwise, options are applicable in all operating
modes.</p>

<p style="margin-top: 1em"><b>@</b><i>archive</i></p>

<p style="margin-left:19%;">(c and r modes only) The
specified archive is opened and the entries in it will be
appended to the current archive. As a simple example,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -c
-f</b> <i>- newfile</i> <b>@</b><i>original.tar</i></p>

<p style="margin-left:19%; margin-top: 1em">writes a new
archive to standard output containing a file <i>newfile</i>
and all of the entries from <i>original.tar</i>. In
contrast,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -c
-f</b> <i>- newfile original.tar</i></p>

<p style="margin-left:19%; margin-top: 1em">creates a new
archive with only two entries. Similarly,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -czf</b>
<i>-</i> <b>--format pax @</b><i>-</i></p>

<p style="margin-left:19%; margin-top: 1em">reads an
archive from standard input (whose format will be determined
automatically) and converts it into a gzip-compressed
pax-format archive on stdout. In this way, <b>tar</b> can be
used to convert archives from one format to another.</p>

<p style="margin-top: 1em"><b>-a</b>,
<b>--auto-compress</b></p>

<p style="margin-left:19%;">(c mode only) Use the archive
suffix to decide a set of the format and the compressions.
As a simple example,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -a
-cf</b> <i>archive.tgz source.c source.h</i></p>

<p style="margin-left:19%; margin-top: 1em">creates a new
archive with restricted pax format and gzip compression,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -a
-cf</b> <i>archive.tar.bz2.uu source.c source.h</i></p>

<p style="margin-left:19%; margin-top: 1em">creates a new
archive with restricted pax format and bzip2 compression and
uuencode compression,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -a
-cf</b> <i>archive.zip source.c source.h</i></p>

<p style="margin-left:19%; margin-top: 1em">creates a new
archive with zip format,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -a
-jcf</b> <i>archive.tgz source.c source.h</i></p>

<p style="margin-left:19%; margin-top: 1em">ignores the
&ldquo;-j&rdquo; option, and creates a new archive with
restricted pax format and gzip compression,</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -a
-jcf</b> <i>archive.xxx source.c source.h</i></p>

<p style="margin-left:19%; margin-top: 1em">if it is
unknown suffix or no suffix, creates a new archive with
restricted pax format and bzip2 compression.</p>

<p style="margin-top: 1em"><b>--acls</b></p>

<p style="margin-left:19%; margin-top: 1em">(c, r, u, x
modes only) Archive or extract POSIX.1e or NFSv4 ACLs. This
is the reverse of <b>--no-acls</b> and the default behavior
in c, r, and u modes (except on Mac OS X) or if <b>tar</b>
is run in x mode as root. On Mac OS X this option translates
extended ACLs to NFSv4 ACLs. To store extended ACLs the
<b>--mac-metadata</b> option is preferred.</p>

<p style="margin-top: 1em"><b>-B</b>,
<b>--read-full-blocks</b></p>

<p style="margin-left:19%;">Ignored for compatibility with
other <i>tar</i>(1) implementations.</p>

<p style="margin-top: 1em"><b>-b</b> <i>blocksize</i>,
<b>--block-size</b> <i>blocksize</i></p>

<p style="margin-left:19%;">Specify the block size, in
512-byte records, for tape drive I/O. As a rule, this
argument is only needed when reading from or writing to tape
drives, and usually not even then as the default block size
of 20 records (10240 bytes) is very common.</p>

<p style="margin-top: 1em"><b>-C</b> <i>directory</i>,
<b>--cd</b> <i>directory</i>, <b>--directory</b>
<i>directory</i></p>

<p style="margin-left:19%;">In c and r mode, this changes
the directory before adding the following files. In x mode,
change directories after opening the archive but before
extracting entries from the archive.</p>

<p style="margin-top: 1em"><b>--chroot</b></p>

<p style="margin-left:19%;">(x mode only) <b>chroot</b>()
to the current directory after processing any <b>-C</b>
options and before extracting any files.</p>

<p style="margin-top: 1em"><b>--clamp-mtime</b></p>

<p style="margin-left:19%;">(use with <b>--mtime</b>) Only
set the modification time if the file is newer than the date
specified in <b>--mtime</b>.</p>


<p style="margin-top: 1em"><b>--clear-nochange-fflags</b></p>

<p style="margin-left:19%;">(x mode only) Before removing
file system objects to replace them, clear platform-specific
file attributes or file flags that might prevent
removal.</p>

<p style="margin-top: 1em"><b>--exclude</b>
<i>pattern</i></p>

<p style="margin-left:19%;">Do not process files or
directories that match the specified pattern. Note that
exclusions take precedence over patterns or filenames
specified on the command line.</p>

<p style="margin-top: 1em"><b>--exclude-vcs</b></p>

<p style="margin-left:19%;">Do not process files or
directories internally used by the version control systems
&lsquo;Arch&rsquo;, &lsquo;Bazaar&rsquo;, &lsquo;CVS&rsquo;,
&lsquo;Darcs&rsquo;, &lsquo;Mercurial&rsquo;,
&lsquo;RCS&rsquo;, &lsquo;SCCS&rsquo;, &lsquo;SVN&rsquo; and
&lsquo;git&rsquo;.</p>

<p style="margin-top: 1em"><b>--fflags</b></p>

<p style="margin-left:19%;">(c, r, u, x modes only) Archive
or extract platform-specific file attributes or file flags.
This is the reverse of <b>--no-fflags</b> and the default
behavior in c, r, and u modes or if <b>tar</b> is run in x
mode as root.</p>

<p style="margin-top: 1em"><b>--format</b>
<i>format</i></p>

<p style="margin-left:19%;">(c, r, u mode only) Use the
specified format for the created archive. Supported formats
include &ldquo;cpio&rdquo;, &ldquo;pax&rdquo;,
&ldquo;shar&rdquo;, and &ldquo;ustar&rdquo;. Other formats
may also be supported; see <i>libarchive-formats</i>(5) for
more information about currently-supported formats. In r and
u modes, when extending an existing archive, the format
specified here must be compatible with the format of the
existing archive on disk.</p>

<p style="margin-top: 1em"><b>-f</b> <i>file</i>,
<b>--file</b> <i>file</i></p>

<p style="margin-left:19%;">Read the archive from or write
the archive to the specified file. The filename can be
<i>-</i> for standard input or standard output. The default
varies by system; on FreeBSD, the default is
<i>/dev/sa0</i>; on Linux, the default is
<i>/dev/st0</i>.</p>

<p style="margin-top: 1em"><b>--gid</b> <i>id</i></p>

<p style="margin-left:19%;">Use the provided group id
number. On extract, this overrides the group id in the
archive; the group name in the archive will be ignored. On
create, this overrides the group id read from disk; if
<b>--gname</b> is not also specified, the group name will be
set to match the group id.</p>

<p style="margin-top: 1em"><b>--gname</b> <i>name</i></p>

<p style="margin-left:19%;">Use the provided group name. On
extract, this overrides the group name in the archive; if
the provided group name does not exist on the system, the
group id (from the archive or from the <b>--gid</b> option)
will be used instead. On create, this sets the group name
that will be stored in the archive; the name will not be
verified against the system group database.</p>

<p style="margin-top: 1em"><b>--group</b>
<i>name</i>[:<i>gid</i>]</p>

<p style="margin-left:19%;">Use the provided group, if
<i>gid</i> is not provided, <i>name</i> can be either a
group name or numeric id. See the <b>--gname</b> option for
details.</p>

<p style="margin-top: 1em"><b>-H</b></p>

<p style="margin-left:19%; margin-top: 1em">(c and r modes
only) Symbolic links named on the command line will be
followed; the target of the link will be archived, not the
link itself.</p>

<p style="margin-top: 1em"><b>-h</b></p>

<p style="margin-left:19%; margin-top: 1em">(c and r modes
only) Synonym for <b>-L</b>.</p>

<p style="margin-top: 1em"><b>-I</b></p>

<p style="margin-left:19%; margin-top: 1em">Synonym for
<b>-T</b>.</p>

<p style="margin-top: 1em"><b>--help</b></p>

<p style="margin-left:19%; margin-top: 1em">Show usage.</p>

<p style="margin-top: 1em"><b>--hfsCompression</b></p>

<p style="margin-left:19%;">(x mode only) Mac OS X specific
(v10.6 or later). Compress extracted regular files with HFS+
compression.</p>

<p style="margin-top: 1em"><b>--ignore-zeros</b></p>

<p style="margin-left:19%;">An alias of <b>--options
read_concatenated_archives</b> for compatibility with GNU
tar.</p>

<p style="margin-top: 1em"><b>--include</b>
<i>pattern</i></p>

<p style="margin-left:19%;">Process only files or
directories that match the specified pattern. Note that
exclusions specified with <b>--exclude</b> take precedence
over inclusions. If no inclusions are explicitly specified,
all entries are processed by default. The <b>--include</b>
option is especially useful when filtering archives. For
example, the command</p>

<p style="margin-left:27%; margin-top: 1em"><b>tar -c
-f</b> <i>new.tar</i> <b>--include=&rsquo;*foo*&rsquo;
@</b><i>old.tgz</i></p>

<p style="margin-left:19%; margin-top: 1em">creates a new
archive <i>new.tar</i> containing only the entries from
<i>old.tgz</i> containing the string &lsquo;foo&rsquo;.</p>

<p style="margin-top: 1em"><b>-J</b>, <b>--xz</b></p>

<p style="margin-left:19%;">(c mode only) Compress the
resulting archive with <i>xz</i>(1). In extract or list
modes, this option is ignored. Note that this <b>tar</b>
implementation recognizes XZ compression automatically when
reading archives.</p>

<p style="margin-top: 1em"><b>-j</b>, <b>--bzip</b>,
<b>--bzip2</b>, <b>--bunzip2</b></p>

<p style="margin-left:19%;">(c mode only) Compress the
resulting archive with <i>bzip2</i>(1). In extract or list
modes, this option is ignored. Note that this <b>tar</b>
implementation recognizes bzip2 compression automatically
when reading archives.</p>

<p style="margin-top: 1em"><b>-k</b>,
<b>--keep-old-files</b></p>

<p style="margin-left:19%;">(x mode only) Do not overwrite
existing files. In particular, if a file appears more than
once in an archive, later copies will not overwrite earlier
copies.</p>

<p style="margin-top: 1em"><b>--keep-newer-files</b></p>

<p style="margin-left:19%;">(x mode only) Do not overwrite
existing files that are newer than the versions appearing in
the archive being extracted.</p>

<p style="margin-top: 1em"><b>-L</b>,
<b>--dereference</b></p>

<p style="margin-left:19%;">(c and r modes only) All
symbolic links will be followed. Normally, symbolic links
are archived as such. With this option, the target of the
link will be archived instead.</p>

<p style="margin-top: 1em"><b>-l</b>,
<b>--check-links</b></p>

<p style="margin-left:19%;">(c and r modes only) Issue a
warning message unless all links to each file are
archived.</p>

<p style="margin-top: 1em"><b>--lrzip</b></p>

<p style="margin-left:19%;">(c mode only) Compress the
resulting archive with <i>lrzip</i>(1). In extract or list
modes, this option is ignored. Note that this <b>tar</b>
implementation recognizes lrzip compression automatically
when reading archives.</p>

<p style="margin-top: 1em"><b>--lz4</b></p>

<p style="margin-left:19%; margin-top: 1em">(c mode only)
Compress the archive with lz4-compatible compression before
writing it. In extract or list modes, this option is
ignored. Note that this <b>tar</b> implementation recognizes
lz4 compression automatically when reading archives.</p>

<p style="margin-top: 1em"><b>--zstd</b></p>

<p style="margin-left:19%; margin-top: 1em">(c mode only)
Compress the archive with zstd-compatible compression before
writing it. In extract or list modes, this option is
ignored. Note that this <b>tar</b> implementation recognizes
zstd compression automatically when reading archives.</p>

<p style="margin-top: 1em"><b>--lzma</b></p>

<p style="margin-left:19%; margin-top: 1em">(c mode only)
Compress the resulting archive with the original LZMA
algorithm. In extract or list modes, this option is ignored.
Use of this option is discouraged and new archives should be
created with <b>--xz</b> instead. Note that this <b>tar</b>
implementation recognizes LZMA compression automatically
when reading archives.</p>

<p style="margin-top: 1em"><b>--lzop</b></p>

<p style="margin-left:19%; margin-top: 1em">(c mode only)
Compress the resulting archive with <i>lzop</i>(1). In
extract or list modes, this option is ignored. Note that
this <b>tar</b> implementation recognizes LZO compression
automatically when reading archives.</p>

<p style="margin-top: 1em"><b>-m</b>,
<b>--modification-time</b></p>

<p style="margin-left:19%;">(x mode only) Do not extract
modification time. By default, the modification time is set
to the time stored in the archive.</p>

<p style="margin-top: 1em"><b>--mac-metadata</b></p>

<p style="margin-left:19%;">(c, r, u and x mode only) Mac
OS X specific. Archive or extract extended ACLs and extended
file attributes using <i>copyfile</i>(3) in AppleDouble
format. This is the reverse of <b>--no-mac-metadata</b>. and
the default behavior in c, r, and u modes or if <b>tar</b>
is run in x mode as root. Currently supported only for pax
formats (</p>

<p>including pax restricted, the default tar format for
<b>bsdtar</b> )</p>

<p style="margin-top: 1em"><b>--mtime</b> <i>date</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Set the
modification times of added files to the specified date.</p>

<p style="margin-top: 1em"><b>-n</b>, <b>--norecurse</b>,
<b>--no-recursion</b></p>

<p style="margin-left:19%;">Do not operate recursively on
the content of directories.</p>

<p style="margin-top: 1em"><b>--newer</b> <i>date</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Only
include files and directories newer than the specified date.
This compares ctime entries.</p>

<p style="margin-top: 1em"><b>--newer-mtime</b>
<i>date</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Like
<b>--newer</b>, except it compares mtime entries instead of
ctime entries.</p>

<p style="margin-top: 1em"><b>--newer-than</b>
<i>file</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Only
include files and directories newer than the specified file.
This compares ctime entries.</p>

<p style="margin-top: 1em"><b>--newer-mtime-than</b>
<i>file</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Like
<b>--newer-than</b>, except it compares mtime entries
instead of ctime entries.</p>

<p style="margin-top: 1em"><b>--nodump</b></p>

<p style="margin-left:19%;">(c and r modes only) Honor the
nodump file flag by skipping this file.</p>


<p style="margin-top: 1em"><b>--nopreserveHFSCompression</b></p>

<p style="margin-left:19%;">(x mode only) Mac OS X specific
(v10.6 or later). Do not compress extracted regular files
which were compressed with HFS+ compression before archived.
By default, compress the regular files again with HFS+
compression.</p>

<p style="margin-top: 1em"><b>--null</b></p>

<p style="margin-left:19%; margin-top: 1em">(use with
<b>-I</b> or <b>-T</b>) Filenames or patterns are separated
by null characters, not by newlines. This is often used to
read filenames output by the <b>-print0</b> option to
<i>find</i>(1).</p>

<p style="margin-top: 1em"><b>--no-acls</b></p>

<p style="margin-left:19%;">(c, r, u, x modes only) Do not
archive or extract POSIX.1e or NFSv4 ACLs. This is the
reverse of <b>--acls</b> and the default behavior if
<b>tar</b> is run as non-root in x mode (on Mac OS X as any
user in c, r, u and x modes).</p>

<p style="margin-top: 1em"><b>--no-fflags</b></p>

<p style="margin-left:19%;">(c, r, u, x modes only) Do not
archive or extract file attributes or file flags. This is
the reverse of <b>--fflags</b> and the default behavior if
<b>tar</b> is run as non-root in x mode.</p>

<p style="margin-top: 1em"><b>--no-mac-metadata</b></p>

<p style="margin-left:19%;">(c, r, u and x mode only) Mac
OS X specific. Do not archive or extract ACLs and extended
file attributes using <i>copyfile</i>(3) in AppleDouble
format. This is the reverse of <b>--mac-metadata</b>. and
the default behavior if <b>tar</b> is run as non-root in x
mode.</p>

<p style="margin-top: 1em"><b>--no-read-sparse</b></p>

<p style="margin-left:19%;">(c, r, u modes only) Do not
read sparse file information from disk. This is the reverse
of <b>--read-sparse</b>.</p>

<p style="margin-top: 1em"><b>--no-safe-writes</b></p>

<p style="margin-left:19%;">(x mode only) Do not create
temporary files and use <i>rename</i>(2) to replace the
original ones. This is the reverse of
<b>--safe-writes</b>.</p>

<p style="margin-top: 1em"><b>--no-same-owner</b></p>

<p style="margin-left:19%;">(x mode only) Do not extract
owner and group IDs. This is the reverse of
<b>--same-owner</b> and the default behavior if <b>tar</b>
is run as non-root.</p>


<p style="margin-top: 1em"><b>--no-same-permissions</b></p>

<p style="margin-left:19%;">(x mode only) Do not extract
full permissions (SGID, SUID, sticky bit, file attributes or
file flags, extended file attributes and ACLs). This is the
reverse of <b>-p</b> and the default behavior if <b>tar</b>
is run as non-root.</p>

<p style="margin-top: 1em"><b>--no-xattrs</b></p>

<p style="margin-left:19%;">(c, r, u, x modes only) Do not
archive or extract extended file attributes. This is the
reverse of <b>--xattrs</b> and the default behavior if
<b>tar</b> is run as non-root in x mode.</p>

<p style="margin-top: 1em"><b>--numeric-owner</b></p>

<p style="margin-left:19%;">This is equivalent to
<b>--uname</b> &quot;&quot; <b>--gname</b> &quot;&quot;. On
extract, it causes user and group names in the archive to be
ignored in favor of the numeric user and group ids. On
create, it causes user and group names to not be stored in
the archive.</p>

<p style="margin-top: 1em"><b>-O</b>,
<b>--to-stdout</b></p>

<p style="margin-left:19%;">(x, t modes only) In extract
(-x) mode, files will be written to standard out rather than
being extracted to disk. In list (-t) mode, the file listing
will be written to stderr rather than the usual stdout.</p>

<p style="margin-top: 1em"><b>-o</b></p>

<p style="margin-left:19%; margin-top: 1em">(x mode) Use
the user and group of the user running the program rather
than those specified in the archive. Note that this has no
significance unless <b>-p</b> is specified, and the program
is being run by the root user. In this case, the file modes
and flags from the archive will be restored, but ACLs or
owner information in the archive will be discarded.</p>

<p style="margin-top: 1em"><b>-o</b></p>

<p style="margin-left:19%; margin-top: 1em">(c, r, u mode)
A synonym for <b>--format</b> <i>ustar</i></p>

<p style="margin-top: 1em"><b>--older</b> <i>date</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Only
include files and directories older than the specified date.
This compares ctime entries.</p>

<p style="margin-top: 1em"><b>--older-mtime</b>
<i>date</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Like
<b>--older</b>, except it compares mtime entries instead of
ctime entries.</p>

<p style="margin-top: 1em"><b>--older-than</b>
<i>file</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Only
include files and directories older than the specified file.
This compares ctime entries.</p>

<p style="margin-top: 1em"><b>--older-mtime-than</b>
<i>file</i></p>

<p style="margin-left:19%;">(c, r, u modes only) Like
<b>--older-than</b>, except it compares mtime entries
instead of ctime entries.</p>

<p style="margin-top: 1em"><b>--one-file-system</b></p>

<p style="margin-left:19%;">(c, r, and u modes) Do not
cross mount points.</p>

<p style="margin-top: 1em"><b>--options</b>
<i>options</i></p>

<p style="margin-left:19%;">Select optional behaviors for
particular modules. The argument is a text string containing
comma-separated keywords and values. These are passed to the
modules that handle particular formats to control how those
formats will behave. Each option has one of the following
forms:</p>

<p style="margin-top: 1em"><i>key=value</i></p>

<p style="margin-left:29%;">The key will be set to the
specified value in every module that supports it. Modules
that do not support this key will ignore it.</p>

<p><i>key</i></p>

<p style="margin-left:29%; margin-top: 1em">The key will be
enabled in every module that supports it. This is equivalent
to <i>key</i><b>=1</b>.</p>

<p><i>!key</i></p>

<p style="margin-left:29%; margin-top: 1em">The key will be
disabled in every module that supports it.</p>

<p><i>module:key=value</i>, <i>module:key</i>,
<i>module:!key</i></p>

<p style="margin-left:29%;">As above, but the corresponding
key and value will be provided only to modules whose name
matches <i>module</i>.</p>

<p style="margin-left:19%; margin-top: 1em">The complete
list of supported modules and keys for create and append
modes is in <i>archive_write_set_options</i>(3) and for
extract and list modes in
<i>archive_read_set_options</i>(3).</p>

<p style="margin-left:19%; margin-top: 1em">Examples of
supported options:</p>

<p style="margin-top: 1em"><b>iso9660:joliet</b></p>

<p style="margin-left:29%;">Support Joliet extensions. This
is enabled by default, use <b>!joliet</b> or
<b>iso9660:!joliet</b> to disable.</p>

<p><b>iso9660:rockridge</b></p>

<p style="margin-left:29%;">Support Rock Ridge extensions.
This is enabled by default, use <b>!rockridge</b> or
<b>iso9660:!rockridge</b> to disable.</p>

<p><b>gzip:compression-level</b></p>

<p style="margin-left:29%;">A decimal integer from 1 to 9
specifying the gzip compression level.</p>

<p><b>gzip:timestamp</b></p>

<p style="margin-left:29%;">Store timestamp. This is
enabled by default, use <b>!timestamp</b> or
<b>gzip:!timestamp</b> to disable.</p>

<p><b>lrzip:compression</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as compression
method. Supported values are bzip2, gzip, lzo (ultra fast),
and zpaq (best, extremely slow).</p>

<p><b>lrzip:compression-level</b></p>

<p style="margin-left:29%;">A decimal integer from 1 to 9
specifying the lrzip compression level.</p>

<p><b>lz4:compression-level</b></p>

<p style="margin-left:29%;">A decimal integer from 1 to 9
specifying the lzop compression level.</p>

<p><b>lz4:stream-checksum</b></p>

<p style="margin-left:29%;">Enable stream checksum. This is
by default, use <b>lz4:!stream-checksum</b> to disable.</p>

<p><b>lz4:block-checksum</b></p>

<p style="margin-left:29%;">Enable block checksum (Disabled
by default).</p>

<p><b>lz4:block-size</b></p>

<p style="margin-left:29%;">A decimal integer from 4 to 7
specifying the lz4 compression block size (7 is set by
default).</p>

<p><b>lz4:block-dependence</b></p>

<p style="margin-left:29%;">Use the previous block of the
block being compressed for a compression dictionary to
improve compression ratio.</p>

<p><b>zstd:compression-level</b>=<i>N</i></p>

<p style="margin-left:29%;">A decimal integer specifying
the zstd compression level. Supported values depend on the
library version, common values are from 1 to 22.</p>

<p><b>zstd:threads</b>=<i>N</i></p>

<p style="margin-left:29%;">Specify the number of worker
threads to use, or 0 to use as many threads as there are CPU
cores in the system.</p>

<p><b>zstd:frame-per-file</b></p>

<p style="margin-left:29%;">Start a new compression frame
at the beginning of each file in the archive.</p>

<p><b>zstd:min-frame-in</b>=<i>N</i></p>

<p style="margin-left:29%;">In combination with
<b>zstd:frame-per-file</b>, do not start a new compression
frame unless the uncompressed size of the current frame is
at least <i>N</i> bytes. The number may be followed by <b>k
/ kB</b>, <b>M / MB</b>, or <b>G / GB</b> to indicate
kilobytes, megabytes or gigabytes respectively.</p>

<p><b>zstd:min-frame-out</b>=<i>N</i>,
<b>zstd:min-frame-size</b>=<i>N</i></p>

<p style="margin-left:29%;">In combination with
<b>zstd:frame-per-file</b>, do not start a new compression
frame unless the compressed size of the current frame is at
least <i>N</i> bytes. The number may be followed by <b>k /
kB</b>, <b>M / MB</b>, or <b>G / GB</b> to indicate
kilobytes, megabytes or gigabytes respectively.</p>

<p><b>zstd:max-frame-in</b>=<i>N</i>,
<b>zstd:max-frame-size</b>=<i>N</i></p>

<p style="margin-left:29%;">Start a new compression frame
as soon as possible after the uncompressed size of the
current frame exceeds <i>N</i> bytes. The number may be
followed by <b>k / kB</b>, <b>M / MB</b>, or <b>G / GB</b>
to indicate kilobytes, megabytes or gigabytes respectively.
Values less than 1,024 will be rejected.</p>

<p><b>zstd:max-frame-out</b>=<i>N</i></p>

<p style="margin-left:29%;">Start a new compression frame
as soon as possible after the compressed size of the current
frame exceeds <i>N</i> bytes. The number may be followed by
<b>k / kB</b>, <b>M / MB</b>, or <b>G / GB</b> to indicate
kilobytes, megabytes or gigabytes respectively. Values less
than 1,024 will be rejected.</p>

<p><b>lzop:compression-level</b></p>

<p style="margin-left:29%;">A decimal integer from 1 to 9
specifying the lzop compression level.</p>

<p><b>xz:compression-level</b></p>

<p style="margin-left:29%;">A decimal integer from 0 to 9
specifying the xz compression level.</p>

<p><b>xz:threads</b></p>

<p style="margin-left:29%;">Specify the number of worker
threads to use. Setting threads to a special value 0 makes
<i>xz</i>(1) use as many threads as there are CPU cores on
the system.</p>

<p><b>mtree:</b><i>keyword</i></p>

<p style="margin-left:29%;">The mtree writer module allows
you to specify which mtree keywords will be included in the
output. Supported keywords include: <b>cksum</b>,
<b>device</b>, <b>flags</b>, <b>gid</b>, <b>gname</b>,
<b>indent</b>, <b>link</b>, <b>md5</b>, <b>mode</b>,
<b>nlink</b>, <b>rmd160</b>, <b>sha1</b>, <b>sha256</b>,
<b>sha384</b>, <b>sha512</b>, <b>size</b>, <b>time</b>,
<b>uid</b>, <b>uname</b>. The default is equivalent to:
&ldquo;device, flags, gid, gname, link, mode, nlink, size,
time, type, uid, uname&rdquo;.</p>

<p><b>mtree:all</b></p>

<p style="margin-left:29%;">Enables all of the above
keywords. You can also use <b>mtree:!all</b> to disable all
keywords.</p>

<p><b>mtree:use-set</b></p>

<p style="margin-left:29%;">Enable generation of
<b>/set</b> lines in the output.</p>

<p><b>mtree:indent</b></p>

<p style="margin-left:29%;">Produce human-readable output
by indenting options and splitting lines to fit into 80
columns.</p>

<p><b>zip:compression</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as compression
method. Supported values are store (uncompressed) and
deflate (gzip algorithm).</p>

<p><b>zip:encryption</b></p>

<p style="margin-left:29%;">Enable encryption using
traditional zip encryption.</p>

<p><b>zip:encryption</b>=<i>type</i></p>

<p style="margin-left:29%;">Use <i>type</i> as encryption
type. Supported values are zipcrypt (traditional zip
encryption), aes128 (WinZip AES-128 encryption) and aes256
(WinZip AES-256 encryption).</p>

<p><b>read_concatenated_archives</b></p>

<p style="margin-left:29%;">Ignore zeroed blocks in the
archive, which occurs when multiple tar archives have been
concatenated together. Without this option, only the
contents of the first concatenated archive would be read.
This option is comparable to the <b>-i</b>,
<b>--ignore-zeros</b> option of GNU tar.</p>

<p style="margin-left:19%; margin-top: 1em">If a provided
option is not supported by any module, that is a fatal
error.</p>

<p style="margin-top: 1em"><b>-P</b>,
<b>--absolute-paths</b></p>

<p style="margin-left:19%;">Preserve pathnames. By default,
absolute pathnames (those that begin with a / character)
have the leading slash removed both when creating archives
and extracting from them. Also, <b>tar</b> will refuse to
extract archive entries whose pathnames contain <i>..</i> or
whose target directory would be altered by a symlink. This
option suppresses these behaviors.</p>

<p style="margin-top: 1em"><b>-p</b>, <b>--insecure</b>,
<b>--preserve-permissions</b></p>

<p style="margin-left:19%;">(x mode only) Preserve file
permissions. Attempt to restore the full permissions,
including file modes, file attributes or file flags,
extended file attributes and ACLs, if available, for each
item extracted from the archive. This is the reverse of
<b>--no-same-permissions</b> and the default if <b>tar</b>
is being run as root. It can be partially overridden by also
specifying <b>--no-acls</b>, <b>--no-fflags</b>,
<b>--no-mac-metadata</b> or <b>--no-xattrs</b>.</p>

<p style="margin-top: 1em"><b>--passphrase</b>
<i>passphrase</i></p>

<p style="margin-left:19%;">The <i>passphrase</i> is used
to extract or create an encrypted archive. Currently, zip is
the only supported format that supports encryption. You
shouldn&rsquo;t use this option unless you realize how
insecure use of this option is.</p>

<p style="margin-top: 1em"><b>--posix</b></p>

<p style="margin-left:19%;">(c, r, u mode only) Synonym for
<b>--format</b> <i>pax</i></p>

<p style="margin-top: 1em"><b>-q</b>,
<b>--fast-read</b></p>

<p style="margin-left:19%;">(x and t mode only) Extract or
list only the first archive entry that matches each pattern
or filename operand. Exit as soon as each specified pattern
or filename has been matched. By default, the archive is
always read to the very end, since there can be multiple
entries with the same name and, by convention, later entries
overwrite earlier entries. This option is provided as a
performance optimization.</p>

<p style="margin-top: 1em"><b>--read-sparse</b></p>

<p style="margin-left:19%;">(c, r, u modes only) Read
sparse file information from disk. This is the reverse of
<b>--no-read-sparse</b> and the default behavior.</p>

<p style="margin-top: 1em"><b>-S</b></p>

<p style="margin-left:19%; margin-top: 1em">(x mode only)
Extract files as sparse files. For every block on disk,
check first if it contains only NULL bytes and seek over it
otherwise. This works similar to the conv=sparse option of
dd.</p>

<p style="margin-top: 1em"><b>-s</b> <i>pattern</i></p>

<p style="margin-left:19%;">Modify file or archive member
names according to <i>pattern</i>. The pattern has the
format <i>/old/new/</i>[bghHprRsS] where <i>old</i> is a
basic regular expression, <i>new</i> is the replacement
string of the matched part, and the optional trailing
letters modify how the replacement is handled. If <i>old</i>
is not matched, the pattern is skipped. Within <i>new</i>,
&#732; is substituted with the match, \1 to \9 with the
content of the corresponding captured group. The optional
trailing g specifies that matching should continue after the
matched part and stop on the first unmatched pattern. The
optional trailing s specifies that the pattern applies to
the value of symbolic links. The optional trailing p
specifies that after a successful substitution the original
path name and the new path name should be printed to
standard error. The optional trailing b specifies that the
substitution should be matched from the beginning of the
string rather than from right after the position at which
the previous matching substitution ended. Optional trailing
H, R, or S characters suppress substitutions for hardlink
targets, regular filenames, or symlink targets,
respectively. Optional trailing h, r, or s characters enable
substitutions for hardlink targets, regular filenames, or
symlink targets, respectively. The default is <i>hrs</i>
which applies substitutions to all names. In particular, it
is never necessary to specify h, r, or s.</p>

<p style="margin-top: 1em"><b>--safe-writes</b></p>

<p style="margin-left:19%;">(x mode only) Extract files
atomically. By default <b>tar</b> unlinks the original file
with the same name as the extracted file (if it exists), and
then creates it immediately under the same name and writes
to it. For a short period of time, applications trying to
access the file might not find it, or see incomplete
results. If <b>--safe-writes</b> is enabled, <b>tar</b>
first creates a unique temporary file, then writes the new
contents to the temporary file, and finally renames the
temporary file to its final name atomically using
<i>rename</i>(2). This guarantees that an application
accessing the file, will either see the old contents or the
new contents at all times.</p>

<p style="margin-top: 1em"><b>--same-owner</b></p>

<p style="margin-left:19%;">(x mode only) Extract owner and
group IDs. This is the reverse of <b>--no-same-owner</b> and
the default behavior if <b>tar</b> is run as root.</p>

<p style="margin-top: 1em"><b>--strip-components</b>
<i>count</i></p>

<p style="margin-left:19%;">Remove the specified number of
leading path elements. Pathnames with fewer elements will be
silently skipped. Note that the pathname is edited after
checking inclusion/exclusion patterns but before security
checks.</p>

<p style="margin-top: 1em"><b>-T</b> <i>filename</i>,
<b>--files-from</b> <i>filename</i></p>

<p style="margin-left:19%;">In x or t mode, <b>tar</b> will
read the list of names to be extracted from <i>filename</i>.
In c mode, <b>tar</b> will read names to be archived from
<i>filename</i>. The special name &ldquo;-C&rdquo; on a line
by itself will cause the current directory to be changed to
the directory specified on the following line. Names are
terminated by newlines unless <b>--null</b> is specified.
Note that <b>--null</b> also disables the special handling
of lines containing &ldquo;-C&rdquo;. Note: If you are
generating lists of files using <i>find</i>(1), you probably
want to use <b>-n</b> as well.</p>

<p style="margin-top: 1em"><b>--totals</b></p>

<p style="margin-left:19%;">(c, r, u modes only) After
archiving all files, print a summary to stderr.</p>

<p style="margin-top: 1em"><b>-U</b>, <b>--unlink</b>,
<b>--unlink-first</b></p>

<p style="margin-left:19%;">(x mode only) Unlink files
before creating them. This can be a minor performance
optimization if most files already exist, but can make
things slower if most files do not already exist. This flag
also causes <b>tar</b> to remove intervening directory
symlinks instead of reporting an error. See the
&ldquo;SECURITY&rdquo; section below for more details.</p>

<p style="margin-top: 1em"><b>--uid</b> <i>id</i></p>

<p style="margin-left:19%;">Use the provided user id number
and ignore the user name from the archive. On create, if
<b>--uname</b> is not also specified, the user name will be
set to match the user id.</p>

<p style="margin-top: 1em"><b>--uname</b> <i>name</i></p>

<p style="margin-left:19%;">Use the provided user name. On
extract, this overrides the user name in the archive; if the
provided user name does not exist on the system, it will be
ignored and the user id (from the archive or from the
<b>--uid</b> option) will be used instead. On create, this
sets the user name that will be stored in the archive; the
name is not verified against the system user database.</p>

<p style="margin-top: 1em"><b>--use-compress-program</b>
<i>program</i></p>

<p style="margin-left:19%;">Pipe the input (in x or t mode)
or the output (in c mode) through <i>program</i> instead of
using the builtin compression support.</p>

<p style="margin-top: 1em"><b>--owner</b>
<i>name</i>[:<i>uid</i>]</p>

<p style="margin-left:19%;">Use the provided user, if
<i>uid</i> is not provided, <i>name</i> can be either an
username or numeric id. See the <b>--uname</b> option for
details.</p>

<p style="margin-top: 1em"><b>-v</b>, <b>--verbose</b></p>

<p style="margin-left:19%;">Produce verbose output. In
create and extract modes, <b>tar</b> will list each file
name as it is read from or written to the archive. In list
mode, <b>tar</b> will produce output similar to that of
<i>ls</i>(1). An additional <b>-v</b> option will also
provide ls-like details in create and extract mode.</p>

<p style="margin-top: 1em"><b>--version</b></p>

<p style="margin-left:19%;">Print version of <b>tar</b> and
<b>libarchive</b>, and exit.</p>

<p style="margin-top: 1em"><b>-w</b>,
<b>--confirmation</b>, <b>--interactive</b></p>

<p style="margin-left:19%;">Ask for confirmation for every
action.</p>

<p style="margin-top: 1em"><b>-X</b> <i>filename</i>,
<b>--exclude-from</b> <i>filename</i></p>

<p style="margin-left:19%;">Read a list of exclusion
patterns from the specified file. See <b>--exclude</b> for
more information about the handling of exclusions.</p>

<p style="margin-top: 1em"><b>--xattrs</b></p>

<p style="margin-left:19%;">(c, r, u, x modes only) Archive
or extract extended file attributes. This is the reverse of
<b>--no-xattrs</b> and the default behavior in c, r, and u
modes or if <b>tar</b> is run in x mode as root.</p>

<p style="margin-top: 1em"><b>-y</b></p>

<p style="margin-left:19%; margin-top: 1em">(c mode only)
Compress the resulting archive with <i>bzip2</i>(1). In
extract or list modes, this option is ignored. Note that
this <b>tar</b> implementation recognizes bzip2 compression
automatically when reading archives.</p>

<p style="margin-top: 1em"><b>-Z</b>, <b>--compress</b>,
<b>--uncompress</b></p>

<p style="margin-left:19%;">(c mode only) Compress the
resulting archive with <i>compress</i>(1). In extract or
list modes, this option is ignored. Note that this
<b>tar</b> implementation recognizes compress compression
automatically when reading archives.</p>

<p style="margin-top: 1em"><b>-z</b>, <b>--gunzip</b>,
<b>--gzip</b></p>

<p style="margin-left:19%;">(c mode only) Compress the
resulting archive with <i>gzip</i>(1). In extract or list
modes, this option is ignored. Note that this <b>tar</b>
implementation recognizes gzip compression automatically
when reading archives.</p>

<p style="margin-top: 1em"><b>ENVIRONMENT</b></p>

<p style="margin-left:9%;">The following environment
variables affect the execution of <b>tar</b>:</p>

<p style="margin-top: 1em">TAR_READER_OPTIONS</p>

<p style="margin-left:19%;">The default options for format
readers and compression readers. The <b>--options</b> option
overrides this.</p>

<p style="margin-top: 1em">TAR_WRITER_OPTIONS</p>

<p style="margin-left:19%;">The default options for format
writers and compression writers. The <b>--options</b> option
overrides this.</p>

<p style="margin-top: 1em">LANG</p>

<p style="margin-left:19%; margin-top: 1em">The locale to
use. See <i>environ</i>(7) for more information.</p>

<p style="margin-top: 1em">TAPE</p>

<p style="margin-left:19%; margin-top: 1em">The default
device. The <b>-f</b> option overrides this. Please see the
description of the <b>-f</b> option above for more
details.</p>

<p style="margin-top: 1em">TZ</p>

<p style="margin-left:19%; margin-top: 1em">The timezone to
use when displaying dates. See <i>environ</i>(7) for more
information.</p>

<p style="margin-top: 1em"><b>EXIT STATUS</b></p>

<p style="margin-left:9%;">The <b>tar</b> utility
exits&nbsp;0 on success, and&nbsp;&gt;0 if an error
occurs.</p>

<p style="margin-top: 1em"><b>EXAMPLES</b></p>

<p style="margin-left:9%;">The following creates a new
archive called <i>file.tar.gz</i> that contains two files
<i>source.c</i> and <i>source.h</i>:</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -czf</b>
<i>file.tar.gz source.c source.h</i></p>

<p style="margin-left:9%; margin-top: 1em">To view a
detailed table of contents for this archive:</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -tvf</b>
<i>file.tar.gz</i></p>

<p style="margin-left:9%; margin-top: 1em">To extract all
entries from the archive on the default tape drive:</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar
-x</b></p>

<p style="margin-left:9%; margin-top: 1em">To examine the
contents of an ISO 9660 cdrom image:</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -tf</b>
<i>image.iso</i></p>

<p style="margin-left:9%; margin-top: 1em">To move file
hierarchies, invoke <b>tar</b> as</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -cf</b>
<i>-</i> <b>-C</b> <i>srcdir .</i> | <b>tar -xpf</b>
<i>-</i> <b>-C</b> <i>destdir</i></p>

<p style="margin-left:9%; margin-top: 1em">or more
traditionally</p>

<p style="margin-left:17%; margin-top: 1em"><b>cd srcdir ;
tar -cf</b> <i>- .</i> | (<i>cd destdir ;</i> <b>tar
-xpf</b> <i>-</i>)</p>

<p style="margin-left:9%; margin-top: 1em">In create mode,
the list of files and directories to be archived can also
include directory change instructions of the form
<b>-C</b><i>foo/baz</i> and archive inclusions of the form
<b>@</b><i>archive-file</i>. For example, the command
line</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -c
-f</b> <i>new.tar foo1</i> <b>@</b><i>old.tgz</i>
<b>-C</b><i>/tmp foo2</i></p>

<p style="margin-left:9%; margin-top: 1em">will create a
new archive <i>new.tar</i>. <b>tar</b> will read the file
<i>foo1</i> from the current directory and add it to the
output archive. It will then read each entry from
<i>old.tgz</i> and add those entries to the output archive.
Finally, it will switch to the <i>/tmp</i> directory and add
<i>foo2</i> to the output archive.</p>

<p style="margin-left:9%; margin-top: 1em">An input file in
<i>mtree</i>(5) format can be used to create an output
archive with arbitrary ownership, permissions, or names that
differ from existing data on disk:</p>

<p style="margin-left:17%; margin-top: 1em">$ cat
input.mtree <br>
#mtree <br>
usr/bin uid=0 gid=0 mode=0755 type=dir <br>
usr/bin/ls uid=0 gid=0 mode=0755 type=file content=myls <br>
$ tar -cvf output.tar @input.mtree</p>

<p style="margin-left:9%; margin-top: 1em">The
<b>--newer</b> and <b>--newer-mtime</b> switches accept a
variety of common date and time specifications, including
&ldquo;12 Mar 2005 7:14:29pm&rdquo;, &ldquo;2005-03-12
19:14&rdquo;, &ldquo;5 minutes ago&rdquo;, and &ldquo;19:14
PST May 1&rdquo;.</p>

<p style="margin-left:9%; margin-top: 1em">The
<b>--options</b> argument can be used to control various
details of archive generation or reading. For example, you
can generate mtree output which only contains <b>type</b>,
<b>time</b>, and <b>uid</b> keywords:</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -cf</b>
<i>file.tar</i> <b>--format=mtree
--options=&rsquo;!all,type,time,uid&rsquo;</b>
<i>dir</i></p>

<p style="margin-left:9%; margin-top: 1em">or you can set
the compression level used by gzip or xz compression:</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -czf</b>
<i>file.tar</i>
<b>--options=&rsquo;compression-level=9&rsquo;</b>.</p>

<p style="margin-left:9%; margin-top: 1em">For more
details, see the explanation of the
<b>archive_read_set_options</b>() and
<b>archive_write_set_options</b>() API calls that are
described in <i>archive_read</i>(3) and
<i>archive_write</i>(3).</p>

<p style="margin-top: 1em"><b>COMPATIBILITY</b></p>

<p style="margin-left:9%;">The bundled-arguments format is
supported for compatibility with historic implementations.
It consists of an initial word (with no leading - character)
in which each character indicates an option. Arguments
follow as separate words. The order of the arguments must
match the order of the corresponding characters in the
bundled command word. For example,</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar tbf
32</b> <i>file.tar</i></p>

<p style="margin-left:9%; margin-top: 1em">specifies three
flags <b>t</b>, <b>b</b>, and <b>f</b>. The <b>b</b> and
<b>f</b> flags both require arguments, so there must be two
additional items on the command line. The <i>32</i> is the
argument to the <b>b</b> flag, and <i>file.tar</i> is the
argument to the <b>f</b> flag.</p>

<p style="margin-left:9%; margin-top: 1em">The mode options
c, r, t, u, and x and the options b, f, l, m, o, v, and w
comply with SUSv2.</p>

<p style="margin-left:9%; margin-top: 1em">For maximum
portability, scripts that invoke <b>tar</b> should use the
bundled-argument format above, should limit themselves to
the <b>c</b>, <b>t</b>, and <b>x</b> modes, and the
<b>b</b>, <b>f</b>, <b>m</b>, <b>v</b>, and <b>w</b>
options.</p>

<p style="margin-left:9%; margin-top: 1em">Additional long
options are provided to improve compatibility with other tar
implementations.</p>

<p style="margin-top: 1em"><b>SECURITY</b></p>

<p style="margin-left:9%;">Certain security issues are
common to many archiving programs, including <b>tar</b>. In
particular, carefully-crafted archives can request that
<b>tar</b> extract files to locations outside of the target
directory. This can potentially be used to cause unwitting
users to overwrite files they did not intend to overwrite.
If the archive is being extracted by the superuser, any file
on the system can potentially be overwritten. There are
three ways this can happen. Although <b>tar</b> has
mechanisms to protect against each one, savvy users should
be aware of the implications:</p>

<p style="margin-top: 1em"><b>&bull;</b></p>

<p style="margin-left:19%;">Archive entries can have
absolute pathnames. By default, <b>tar</b> removes the
leading <i>/</i> character from filenames before restoring
them to guard against this problem.</p>

<p style="margin-top: 1em"><b>&bull;</b></p>

<p style="margin-left:19%;">Archive entries can have
pathnames that include <i>..</i> components. By default,
<b>tar</b> will not extract files containing <i>..</i>
components in their pathname.</p>

<p style="margin-top: 1em"><b>&bull;</b></p>

<p style="margin-left:19%;">Archive entries can exploit
symbolic links to restore files to other directories. An
archive can restore a symbolic link to another directory,
then use that link to restore a file into that directory. To
guard against this, <b>tar</b> checks each extracted path
for symlinks. If the final path element is a symlink, it
will be removed and replaced with the archive entry. If
<b>-U</b> is specified, any intermediate symlink will also
be unconditionally removed. If neither <b>-U</b> nor
<b>-P</b> is specified, <b>tar</b> will refuse to extract
the entry.</p>

<p style="margin-left:9%; margin-top: 1em">To protect
yourself, you should be wary of any archives that come from
untrusted sources. You should examine the contents of an
archive with</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -tf</b>
<i>filename</i></p>

<p style="margin-left:9%; margin-top: 1em">before
extraction. You should use the <b>-k</b> option to ensure
that <b>tar</b> will not overwrite any existing files or the
<b>-U</b> option to remove any pre-existing files. You
should generally not extract archives while running with
super-user privileges. Note that the <b>-P</b> option to
<b>tar</b> disables the security checks above and allows you
to extract an archive while preserving any absolute
pathnames, <i>..</i> components, or symlinks to other
directories.</p>

<p style="margin-top: 1em"><b>SEE ALSO</b></p>

<p style="margin-left:9%;"><i>bzip2</i>(1),
<i>compress</i>(1), <i>cpio</i>(1), <i>gzip</i>(1),
<i>mt</i>(1), <i>pax</i>(1), <i>shar</i>(1), <i>xz</i>(1),
<i>libarchive</i>(3), <i>libarchive-formats</i>(5),
<i>tar</i>(5)</p>

<p style="margin-top: 1em"><b>STANDARDS</b></p>

<p style="margin-left:9%;">There is no current POSIX
standard for the tar command; it appeared in ISO/IEC
9945-1:1996 (&ldquo;POSIX.1&rdquo;) but was dropped from
IEEE Std 1003.1-2001 (&ldquo;POSIX.1&rdquo;). The options
supported 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.</p>

<p style="margin-left:9%; margin-top: 1em">The ustar and
pax interchange file formats are defined by IEEE Std
1003.1-2001 (&ldquo;POSIX.1&rdquo;) for the pax command.</p>

<p style="margin-top: 1em"><b>HISTORY</b></p>

<p style="margin-left:9%;">A <b>tar</b> command appeared in
Seventh Edition Unix, which was released in January, 1979.
There have been numerous other implementations, many of
which extended the file format. John Gilmore&rsquo;s
<b>pdtar</b> 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&nbsp;1.0.</p>

<p style="margin-left:9%; margin-top: 1em">This is a
complete re-implementation based on the <i>libarchive</i>(3)
library. It was first released with FreeBSD&nbsp;5.4 in May,
2005.</p>

<p style="margin-top: 1em"><b>BUGS</b></p>

<p style="margin-left:9%;">This program follows ISO/IEC
9945-1:1996 (&ldquo;POSIX.1&rdquo;) for the definition of
the <b>-l</b> option. Note that GNU tar prior to version
1.15 treated <b>-l</b> as a synonym for the
<b>--one-file-system</b> option.</p>

<p style="margin-left:9%; margin-top: 1em">The <b>-C</b>
<i>dir</i> option may differ from historic
implementations.</p>

<p style="margin-left:9%; margin-top: 1em">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 <i>gzip</i>(1) and
<i>bzip2</i>(1), complain about the null padding when
decompressing an archive created by <b>tar</b>, although
they still extract it correctly.</p>

<p style="margin-left:9%; margin-top: 1em">The compression
and decompression is implemented internally, so there may be
insignificant differences between the compressed output
generated by</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -czf</b>
<i>- file</i></p>

<p style="margin-left:9%; margin-top: 1em">and that
generated by</p>

<p style="margin-left:17%; margin-top: 1em"><b>tar -cf</b>
<i>- file</i> | <b>gzip</b></p>

<p style="margin-left:9%; margin-top: 1em">The default
should be to read and write archives to the standard I/O
paths, but tradition (and POSIX) dictates otherwise.</p>

<p style="margin-left:9%; margin-top: 1em">The <b>r</b> and
<b>u</b> modes require that the archive be uncompressed and
located in a regular file on disk. Other archives can be
modified using <b>c</b> mode with the <i>@archive-file</i>
extension.</p>

<p style="margin-left:9%; margin-top: 1em">To archive a
file called <i>@foo</i> or <i>-foo</i> you must specify it
as <i>./@foo</i> or <i>./-foo</i>, respectively.</p>

<p style="margin-left:9%; margin-top: 1em">In create mode,
a leading <i>./</i> is always removed. A leading <i>/</i> is
stripped unless the <b>-P</b> option is specified.</p>

<p style="margin-left:9%; margin-top: 1em">There needs to
be better support for file selection on both create and
extract.</p>

<p style="margin-left:9%; margin-top: 1em">There is not yet
any support for multi-volume archives.</p>

<p style="margin-left:9%; margin-top: 1em">Converting
between dissimilar archive formats (such as tar and cpio)
using the <b>@</b><i>-</i> convention can cause hard link
information to be lost. This is a consequence of the
incompatible ways that different archive formats store
hardlink information. Debian April 23, 2024
<i>TAR</i>(1)</p>
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