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+<html lang="en">
+<head>
+<title>Gzip User's Manual</title>
+<meta http-equiv="Content-Type" content="text/html">
+<meta name="description" content="Gzip User's Manual">
+<meta name="generator" content="makeinfo 4.7">
+<link title="Top" rel="top" href="#Top">
+<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
+<meta http-equiv="Content-Style-Type" content="text/css">
+<style type="text/css"><!--
+ pre.display { font-family:inherit }
+ pre.format { font-family:inherit }
+ pre.smalldisplay { font-family:inherit; font-size:smaller }
+ pre.smallformat { font-family:inherit; font-size:smaller }
+ pre.smallexample { font-size:smaller }
+ pre.smalllisp { font-size:smaller }
+ span.sc { font-variant:small-caps }
+ span.roman { font-family: serif; font-weight: normal; }
+--></style>
+</head>
+<body>
+<h1 class="settitle">Gzip User's Manual</h1>
+<div class="node">
+<p><hr>
+<a name="Top"></a>Up:&nbsp;<a rel="up" accesskey="u" href="#dir">(dir)</a>
+<br>
+</div>
+
+<ul class="menu">
+<li><a accesskey="1" href="#Copying">Copying</a>: How you can copy and share <code>gzip</code>.
+<li><a accesskey="2" href="#Overview">Overview</a>: Preliminary information.
+<li><a accesskey="3" href="#Sample">Sample</a>: Sample output from <code>gzip</code>.
+<li><a accesskey="4" href="#Invoking-gzip">Invoking gzip</a>: How to run <code>gzip</code>.
+<li><a accesskey="5" href="#Advanced-usage">Advanced usage</a>: Concatenated files.
+<li><a accesskey="6" href="#Environment">Environment</a>: The <code>GZIP</code> environment variable
+<li><a accesskey="7" href="#Tapes">Tapes</a>: Using <code>gzip</code> on tapes.
+<li><a accesskey="8" href="#Problems">Problems</a>: Reporting bugs.
+<li><a accesskey="9" href="#Concept-Index">Concept Index</a>: Index of concepts.
+</ul>
+
+<div class="node">
+<p><hr>
+<a name="Copying"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Overview">Overview</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="unnumbered">GNU GENERAL PUBLIC LICENSE</h2>
+
+<div align="center">Version 2, June 1991</div>
+
+<pre class="display"> Copyright &copy; 1989, 1991 Free Software Foundation, Inc.
+ 675 Mass Ave, Cambridge, MA 02139, USA
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+</pre>
+ <h3 class="unnumberedsec">Preamble</h3>
+
+<p>The licenses for most software are designed to take away your
+freedom to share and change it. By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software&mdash;to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.) You can apply it to
+your programs, too.
+
+ <p>When we speak of free software, we are referring to freedom, not
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+ <p>To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+ <p>For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have. You must make sure that they, too, receive or can get the
+source code. And you must show them these terms so they know their
+rights.
+
+ <p>We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+ <p>Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software. If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+ <p>Finally, any free program is threatened constantly by software
+patents. We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary. To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+ <p>The precise terms and conditions for copying, distribution and
+modification follow.
+
+ <ol type=1 start=1>
+<li>This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License. The &ldquo;Program&rdquo;, below,
+refers to any such program or work, and a &ldquo;work based on the Program&rdquo;
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language. (Hereinafter, translation is included without limitation in
+the term &ldquo;modification&rdquo;.) Each licensee is addressed as &ldquo;you&rdquo;.
+
+ <p>Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope. The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+ <li>You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+ <p>You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+ <li>You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+ <ol type=a start=1>
+<li>You must cause the modified files to carry prominent notices
+stating that you changed the files and the date of any change.
+
+ <li>You must cause any work that you distribute or publish, that in
+whole or in part contains or is derived from the Program or any
+part thereof, to be licensed as a whole at no charge to all third
+parties under the terms of this License.
+
+ <li>If the modified program normally reads commands interactively
+when run, you must cause it, when started running for such
+interactive use in the most ordinary way, to print or display an
+announcement including an appropriate copyright notice and a
+notice that there is no warranty (or else, saying that you provide
+a warranty) and that users may redistribute the program under
+these conditions, and telling the user how to view a copy of this
+License. (Exception: if the Program itself is interactive but
+does not normally print such an announcement, your work based on
+the Program is not required to print an announcement.)
+ </ol>
+
+ <p>These requirements apply to the modified work as a whole. If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works. But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+ <p>Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+ <p>In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+ <li>You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+ <ol type=a start=1>
+<li>Accompany it with the complete corresponding machine-readable
+source code, which must be distributed under the terms of Sections
+1 and 2 above on a medium customarily used for software interchange; or,
+
+ <li>Accompany it with a written offer, valid for at least three
+years, to give any third party, for a charge no more than your
+cost of physically performing source distribution, a complete
+machine-readable copy of the corresponding source code, to be
+distributed under the terms of Sections 1 and 2 above on a medium
+customarily used for software interchange; or,
+
+ <li>Accompany it with the information you received as to the offer
+to distribute corresponding source code. (This alternative is
+allowed only for noncommercial distribution and only if you
+received the program in object code or executable form with such
+an offer, in accord with Subsection b above.)
+ </ol>
+
+ <p>The source code for a work means the preferred form of the work for
+making modifications to it. For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable. However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+ <p>If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+ <li>You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License. Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+ <li>You are not required to accept this License, since you have not
+signed it. However, nothing else grants you permission to modify or
+distribute the Program or its derivative works. These actions are
+prohibited by law if you do not accept this License. Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+ <li>Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions. You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+ <li>If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License. If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all. For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+ <p>If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+ <p>It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices. Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+ <p>This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+ <li>If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded. In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+ <li>The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time. Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+ <p>Each version is given a distinguishing version number. If the Program
+specifies a version number of this License which applies to it and &ldquo;any
+later version&rdquo;, you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation. If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+ <li>If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission. For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this. Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+ <li>BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM &ldquo;AS IS&rdquo; WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+ <li>IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+ </ol>
+
+<h3 class="unnumberedsec">How to Apply These Terms to Your New Programs</h3>
+
+<p>If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ <p>To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the &ldquo;copyright&rdquo; line and a pointer to where the full notice is found.
+
+<pre class="smallexample"> <var>one line to give the program's name and an idea of what it does.</var>
+ Copyright (C) 19<var>yy</var> <var>name of author</var>
+
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License
+ as published by the Free Software Foundation; either version 2
+ of the License, or (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+</pre>
+ <p>Also add information on how to contact you by electronic and paper mail.
+
+ <p>If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+<pre class="smallexample"> Gnomovision version 69, Copyright (C) 19<var>yy</var> <var>name of author</var>
+ Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+ type `show w'. This is free software, and you are welcome
+ to redistribute it under certain conditions; type `show c'
+ for details.
+</pre>
+ <p>The hypothetical commands <span class="samp">show w</span> and <span class="samp">show c</span> should show
+the appropriate parts of the General Public License. Of course, the
+commands you use may be called something other than <span class="samp">show w</span> and
+<span class="samp">show c</span>; they could even be mouse-clicks or menu items&mdash;whatever
+suits your program.
+
+ <p>You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a &ldquo;copyright disclaimer&rdquo; for the program, if
+necessary. Here is a sample; alter the names:
+
+<pre class="example"> Yoyodyne, Inc., hereby disclaims all copyright
+ interest in the program `Gnomovision'
+ (which makes passes at compilers) written
+ by James Hacker.
+
+ <var>signature of Ty Coon</var>, 1 April 1989
+ Ty Coon, President of Vice
+</pre>
+ <p>This General Public License does not permit incorporating your program into
+proprietary programs. If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library. If this is what you want to do, use the GNU Library General
+Public License instead of this License.
+
+<div class="node">
+<p><hr>
+<a name="Overview"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Sample">Sample</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" href="#Copying">Copying</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="chapter">1 Overview</h2>
+
+<p><a name="index-overview-1"></a>
+<code>gzip</code> reduces the size of the named files using Lempel-Ziv coding
+(LZ77). Whenever possible, each file is replaced by one with the
+extension <span class="samp">.gz</span>, while keeping the same ownership modes, access and
+modification times. (The default extension is <span class="samp">-gz</span> for VMS,
+<span class="samp">z</span> for MSDOS, OS/2 FAT and Atari.) If no files are specified or
+if a file name is "-", the standard input is compressed to the standard
+output. <code>gzip</code> will only attempt to compress regular files. In
+particular, it will ignore symbolic links.
+
+ <p>If the new file name is too long for its file system, <code>gzip</code>
+truncates it. <code>gzip</code> attempts to truncate only the parts of the
+file name longer than 3 characters. (A part is delimited by dots.) If
+the name consists of small parts only, the longest parts are truncated.
+For example, if file names are limited to 14 characters, gzip.msdos.exe
+is compressed to gzi.msd.exe.gz. Names are not truncated on systems
+which do not have a limit on file name length.
+
+ <p>By default, <code>gzip</code> keeps the original file name and timestamp in
+the compressed file. These are used when decompressing the file with the
+<span class="samp">-N</span> option. This is useful when the compressed file name was
+truncated or when the time stamp was not preserved after a file
+transfer.
+
+ <p>Compressed files can be restored to their original form using <span class="samp">gzip -d</span>
+or <code>gunzip</code> or <code>zcat</code>. If the original name saved in the
+compressed file is not suitable for its file system, a new name is
+constructed from the original one to make it legal.
+
+ <p><code>gunzip</code> takes a list of files on its command line and replaces
+each file whose name ends with <span class="samp">.gz</span>, <span class="samp">.z</span>, <span class="samp">.Z</span>,
+<span class="samp">-gz</span>, <span class="samp">-z</span> or <span class="samp">_z</span> and which begins with the correct
+magic number with an uncompressed file without the original extension.
+<code>gunzip</code> also recognizes the special extensions <span class="samp">.tgz</span> and
+<span class="samp">.taz</span> as shorthands for <span class="samp">.tar.gz</span> and <span class="samp">.tar.Z</span>
+respectively. When compressing, <code>gzip</code> uses the <span class="samp">.tgz</span>
+extension if necessary instead of truncating a file with a <span class="samp">.tar</span>
+extension.
+
+ <p><code>gunzip</code> can currently decompress files created by <code>gzip</code>,
+<code>zip</code>, <code>compress</code> or <code>pack</code>. The detection of the input
+format is automatic. When using the first two formats, <code>gunzip</code>
+checks a 32 bit CRC (cyclic redundancy check). For <code>pack</code>,
+<code>gunzip</code> checks the uncompressed length. The <code>compress</code> format
+was not designed to allow consistency checks. However <code>gunzip</code> is
+sometimes able to detect a bad <span class="samp">.Z</span> file. If you get an error when
+uncompressing a <span class="samp">.Z</span> file, do not assume that the <span class="samp">.Z</span> file is
+correct simply because the standard <code>uncompress</code> does not complain.
+This generally means that the standard <code>uncompress</code> does not check
+its input, and happily generates garbage output. The SCO <span class="samp">compress
+-H</span> format (<code>lzh</code> compression method) does not include a CRC but
+also allows some consistency checks.
+
+ <p>Files created by <code>zip</code> can be uncompressed by <code>gzip</code> only if
+they have a single member compressed with the 'deflation' method. This
+feature is only intended to help conversion of <code>tar.zip</code> files to
+the <code>tar.gz</code> format. To extract <code>zip</code> files with several
+members, use <code>unzip</code> instead of <code>gunzip</code>.
+
+ <p><code>zcat</code> is identical to <span class="samp">gunzip -c</span>. <code>zcat</code>
+uncompresses either a list of files on the command line or its standard
+input and writes the uncompressed data on standard output. <code>zcat</code>
+will uncompress files that have the correct magic number whether they
+have a <span class="samp">.gz</span> suffix or not.
+
+ <p><code>gzip</code> uses the Lempel-Ziv algorithm used in <code>zip</code> and PKZIP.
+The amount of compression obtained depends on the size of the input and
+the distribution of common substrings. Typically, text such as source
+code or English is reduced by 60-70%. Compression is generally much
+better than that achieved by LZW (as used in <code>compress</code>), Huffman
+coding (as used in <code>pack</code>), or adaptive Huffman coding
+(<code>compact</code>).
+
+ <p>Compression is always performed, even if the compressed file is slightly
+larger than the original. The worst case expansion is a few bytes for
+the <code>gzip</code> file header, plus 5 bytes every 32K block, or an expansion
+ratio of 0.015% for large files. Note that the actual number of used
+disk blocks almost never increases. <code>gzip</code> preserves the mode,
+ownership and timestamps of files when compressing or decompressing.
+
+<div class="node">
+<p><hr>
+<a name="Sample"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Invoking-gzip">Invoking gzip</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" href="#Overview">Overview</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="chapter">2 Sample Output</h2>
+
+<p><a name="index-sample-2"></a>
+Here are some realistic examples of running <code>gzip</code>.
+
+ <p>This is the output of the command <span class="samp">gzip -h</span>:
+
+<pre class="example"> gzip 1.2.4 (18 Aug 93)
+ usage: gzip [-cdfhlLnNrtvV19] [-S suffix] [file ...]
+ -c --stdout write on standard output, keep original files unchanged
+ -d --decompress decompress
+ -f --force force overwrite of output file and compress links
+ -h --help give this help
+ -l --list list compressed file contents
+ -L --license display software license
+ -n --no-name do not save or restore the original name and time stamp
+ -N --name save or restore the original name and time stamp
+ -q --quiet suppress all warnings
+ -r --recursive operate recursively on directories
+ -S .suf --suffix .suf use suffix .suf on compressed files
+ -t --test test compressed file integrity
+ -v --verbose verbose mode
+ -V --version display version number
+ -1 --fast compress faster
+ -9 --best compress better
+ file... files to (de)compress. If none given, use standard input.
+</pre>
+ <p>This is the output of the command <span class="samp">gzip -v texinfo.tex</span>:
+
+<pre class="example"> texinfo.tex: 71.6% -- replaced with texinfo.tex.gz
+</pre>
+ <p>The following command will find all <code>gzip</code> files in the current
+directory and subdirectories, and extract them in place without
+destroying the original:
+
+<pre class="example"> find . -name '*.gz' -print | sed 's/^\(.*\)[.]gz$/gunzip &lt; "&amp;" &gt; "\1"/' | sh
+</pre>
+ <div class="node">
+<p><hr>
+<a name="Invoking-gzip"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Advanced-usage">Advanced usage</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" href="#Sample">Sample</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="chapter">3 Invoking <code>gzip</code></h2>
+
+<p><a name="index-invoking-3"></a><a name="index-options-4"></a>
+The format for running the <code>gzip</code> program is:
+
+<pre class="example"> gzip <var>option</var> ...
+</pre>
+ <p><code>gzip</code> supports the following options:
+
+ <dl>
+<dt><span class="samp">--stdout</span><dt><span class="samp">--to-stdout</span><dt><span class="samp">-c</span><dd>Write output on standard output; keep original files unchanged.
+If there are several input files, the output consists of a sequence of
+independently compressed members. To obtain better compression,
+concatenate all input files before compressing them.
+
+ <br><dt><span class="samp">--decompress</span><dt><span class="samp">--uncompress</span><dt><span class="samp">-d</span><dd>Decompress.
+
+ <br><dt><span class="samp">--force</span><dt><span class="samp">-f</span><dd>Force compression or decompression even if the file has multiple links
+or the corresponding file already exists, or if the compressed data
+is read from or written to a terminal. If the input data is not in
+a format recognized by <code>gzip</code>, and if the option <span class="samp">--stdout</span> is also
+given, copy the input data without change to the standard output: let
+<code>zcat</code> behave as <code>cat</code>. If <span class="samp">-f</span> is not given, and
+when not running in the background, <code>gzip</code> prompts to verify
+whether an existing file should be overwritten.
+
+ <br><dt><span class="samp">--help</span><dt><span class="samp">-h</span><dd>Print an informative help message describing the options then quit.
+
+ <br><dt><span class="samp">--list</span><dt><span class="samp">-l</span><dd>For each compressed file, list the following fields:
+
+ <pre class="example"> compressed size: size of the compressed file
+ uncompressed size: size of the uncompressed file
+ ratio: compression ratio (0.0% if unknown)
+ uncompressed_name: name of the uncompressed file
+ </pre>
+ <p>The uncompressed size is given as <span class="samp">-1</span> for files not in <code>gzip</code>
+format, such as compressed <span class="samp">.Z</span> files. To get the uncompressed size for
+such a file, you can use:
+
+ <pre class="example"> zcat file.Z | wc -c
+ </pre>
+ <p>In combination with the <span class="samp">--verbose</span> option, the following fields are also
+displayed:
+
+ <pre class="example"> method: compression method (deflate,compress,lzh,pack)
+ crc: the 32-bit CRC of the uncompressed data
+ date &amp; time: time stamp for the uncompressed file
+ </pre>
+ <p>The crc is given as ffffffff for a file not in gzip format.
+
+ <p>With <span class="samp">--verbose</span>, the size totals and compression ratio for all files
+is also displayed, unless some sizes are unknown. With <span class="samp">--quiet</span>,
+the title and totals lines are not displayed.
+
+ <br><dt><span class="samp">--license</span><dt><span class="samp">-L</span><dd>Display the <code>gzip</code> license then quit.
+
+ <br><dt><span class="samp">--no-name</span><dt><span class="samp">-n</span><dd>When compressing, do not save the original file name and time stamp by
+default. (The original name is always saved if the name had to be
+truncated.) When decompressing, do not restore the original file name
+if present (remove only the <code>gzip</code>
+suffix from the compressed file name) and do not restore the original
+time stamp if present (copy it from the compressed file). This option
+is the default when decompressing.
+
+ <br><dt><span class="samp">--name</span><dt><span class="samp">-N</span><dd>When compressing, always save the original file name and time stamp; this
+is the default. When decompressing, restore the original file name and
+time stamp if present. This option is useful on systems which have
+a limit on file name length or when the time stamp has been lost after
+a file transfer.
+
+ <br><dt><span class="samp">--quiet</span><dt><span class="samp">-q</span><dd>Suppress all warning messages.
+
+ <br><dt><span class="samp">--recursive</span><dt><span class="samp">-r</span><dd>Travel the directory structure recursively. If any of the file names
+specified on the command line are directories, <code>gzip</code> will descend
+into the directory and compress all the files it finds there (or
+decompress them in the case of <code>gunzip</code>).
+
+ <br><dt><span class="samp">--suffix </span><var>suf</var><dt><span class="samp">-S </span><var>suf</var><dd>Use suffix <var>suf</var> instead of <span class="samp">.gz</span>. Any suffix can be
+given, but suffixes other than <span class="samp">.z</span> and <span class="samp">.gz</span> should be
+avoided to avoid confusion when files are transferred to other systems.
+A null suffix forces gunzip to try decompression on all given files
+regardless of suffix, as in:
+
+ <pre class="example"> gunzip -S "" * (*.* for MSDOS)
+ </pre>
+ <p>Previous versions of gzip used the <span class="samp">.z</span> suffix. This was changed to
+avoid a conflict with <code>pack</code>.
+
+ <br><dt><span class="samp">--test</span><dt><span class="samp">-t</span><dd>Test. Check the compressed file integrity.
+
+ <br><dt><span class="samp">--verbose</span><dt><span class="samp">-v</span><dd>Verbose. Display the name and percentage reduction for each file compressed.
+
+ <br><dt><span class="samp">--version</span><dt><span class="samp">-V</span><dd>Version. Display the version number and compilation options, then quit.
+
+ <br><dt><span class="samp">--fast</span><dt><span class="samp">--best</span><dt><span class="samp">-</span><var>n</var><dd>Regulate the speed of compression using the specified digit <var>n</var>,
+where <span class="samp">-1</span> or <span class="samp">--fast</span> indicates the fastest compression
+method (less compression) and <span class="samp">--best</span> or <span class="samp">-9</span> indicates the
+slowest compression method (optimal compression). The default
+compression level is <span class="samp">-6</span> (that is, biased towards high compression at
+expense of speed).
+</dl>
+
+<div class="node">
+<p><hr>
+<a name="Advanced-usage"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Environment">Environment</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" href="#Invoking-gzip">Invoking gzip</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="chapter">4 Advanced usage</h2>
+
+<p><a name="index-concatenated-files-5"></a>
+Multiple compressed files can be concatenated. In this case,
+<code>gunzip</code> will extract all members at once. If one member is
+damaged, other members might still be recovered after removal of the
+damaged member. Better compression can be usually obtained if all
+members are decompressed and then recompressed in a single step.
+
+ <p>This is an example of concatenating <code>gzip</code> files:
+
+<pre class="example"> gzip -c file1 &gt; foo.gz
+ gzip -c file2 &gt;&gt; foo.gz
+</pre>
+ <p>Then
+
+<pre class="example"> gunzip -c foo
+</pre>
+ <p>is equivalent to
+
+<pre class="example"> cat file1 file2
+</pre>
+ <p>In case of damage to one member of a <span class="samp">.gz</span> file, other members can
+still be recovered (if the damaged member is removed). However,
+you can get better compression by compressing all members at once:
+
+<pre class="example"> cat file1 file2 | gzip &gt; foo.gz
+</pre>
+ <p>compresses better than
+
+<pre class="example"> gzip -c file1 file2 &gt; foo.gz
+</pre>
+ <p>If you want to recompress concatenated files to get better compression, do:
+
+<pre class="example"> zcat old.gz | gzip &gt; new.gz
+</pre>
+ <p>If a compressed file consists of several members, the uncompressed
+size and CRC reported by the <span class="samp">--list</span> option applies to the last member
+only. If you need the uncompressed size for all members, you can use:
+
+<pre class="example"> zcat file.gz | wc -c
+</pre>
+ <p>If you wish to create a single archive file with multiple members so
+that members can later be extracted independently, use an archiver such
+as <code>tar</code> or <code>zip</code>. GNU <code>tar</code> supports the <span class="samp">-z</span>
+option to invoke <code>gzip</code> transparently. <code>gzip</code> is designed as a
+complement to <code>tar</code>, not as a replacement.
+
+<div class="node">
+<p><hr>
+<a name="Environment"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Tapes">Tapes</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" href="#Advanced-usage">Advanced usage</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="chapter">5 Environment</h2>
+
+<p><a name="index-Environment-6"></a>
+The environment variable <code>GZIP</code> can hold a set of default options for
+<code>gzip</code>. These options are interpreted first and can be overwritten by
+explicit command line parameters. For example:
+
+<pre class="example"> for sh: GZIP="-8v --name"; export GZIP
+ for csh: setenv GZIP "-8v --name"
+ for MSDOS: set GZIP=-8v --name
+</pre>
+ <p>On Vax/VMS, the name of the environment variable is <code>GZIP_OPT</code>, to
+avoid a conflict with the symbol set for invocation of the program.
+
+<div class="node">
+<p><hr>
+<a name="Tapes"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Problems">Problems</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" href="#Environment">Environment</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="chapter">6 Using <code>gzip</code> on tapes</h2>
+
+<p><a name="index-tapes-7"></a>
+When writing compressed data to a tape, it is generally necessary to pad
+the output with zeroes up to a block boundary. When the data is read and
+the whole block is passed to <code>gunzip</code> for decompression,
+<code>gunzip</code> detects that there is extra trailing garbage after the
+compressed data and emits a warning by default. You have to use the
+<span class="samp">--quiet</span> option to suppress the warning. This option can be set in the
+<code>GZIP</code> environment variable, as in:
+
+<pre class="example"> for sh: GZIP="-q" tar -xfz --block-compress /dev/rst0
+ for csh: (setenv GZIP "-q"; tar -xfz --block-compress /dev/rst0)
+</pre>
+ <p>In the above example, <code>gzip</code> is invoked implicitly by the <span class="samp">-z</span>
+option of GNU <code>tar</code>. Make sure that the same block size (<span class="samp">-b</span>
+option of <code>tar</code>) is used for reading and writing compressed data on
+tapes. (This example assumes you are using the GNU version of
+<code>tar</code>.)
+
+<div class="node">
+<p><hr>
+<a name="Problems"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#Concept-Index">Concept Index</a>,
+Previous:&nbsp;<a rel="previous" accesskey="p" href="#Tapes">Tapes</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="chapter">7 Reporting Bugs</h2>
+
+<p><a name="index-bugs-8"></a>
+If you find a bug in <code>gzip</code>, please send electronic mail to
+<span class="samp">bug-gzip@gnu.org</span><!-- /@w -->. Include the version number,
+which you can find by running <span class="samp">gzip&nbsp;-V</span><!-- /@w -->. Also include in your
+message the hardware and operating system, the compiler used to compile
+<code>gzip</code>,
+a description of the bug behavior, and the input to <code>gzip</code> that triggered
+the bug.
+
+<div class="node">
+<p><hr>
+<a name="Concept-Index"></a>Previous:&nbsp;<a rel="previous" accesskey="p" href="#Problems">Problems</a>,
+Up:&nbsp;<a rel="up" accesskey="u" href="#Top">Top</a>
+<br>
+</div>
+
+<h2 class="unnumbered">Concept Index</h2>
+
+<ul class="index-cp" compact>
+<li><a href="#index-bugs-8">bugs</a>: <a href="#Problems">Problems</a></li>
+<li><a href="#index-concatenated-files-5">concatenated files</a>: <a href="#Advanced-usage">Advanced usage</a></li>
+<li><a href="#index-Environment-6">Environment</a>: <a href="#Environment">Environment</a></li>
+<li><a href="#index-invoking-3">invoking</a>: <a href="#Invoking-gzip">Invoking gzip</a></li>
+<li><a href="#index-options-4">options</a>: <a href="#Invoking-gzip">Invoking gzip</a></li>
+<li><a href="#index-overview-1">overview</a>: <a href="#Overview">Overview</a></li>
+<li><a href="#index-sample-2">sample</a>: <a href="#Sample">Sample</a></li>
+<li><a href="#index-tapes-7">tapes</a>: <a href="#Tapes">Tapes</a></li>
+</ul>
+<div class="contents">
+<h2>Table of Contents</h2>
+<ul>
+<li><a name="toc_Copying" href="#Copying">GNU GENERAL PUBLIC LICENSE</a>
+<ul>
+<li><a href="#Copying">Preamble</a>
+<li><a href="#Copying">How to Apply These Terms to Your New Programs</a>
+</li></ul>
+<li><a name="toc_Overview" href="#Overview">1 Overview</a>
+<li><a name="toc_Sample" href="#Sample">2 Sample Output</a>
+<li><a name="toc_Invoking-gzip" href="#Invoking-gzip">3 Invoking <code>gzip</code></a>
+<li><a name="toc_Advanced-usage" href="#Advanced-usage">4 Advanced usage</a>
+<li><a name="toc_Environment" href="#Environment">5 Environment</a>
+<li><a name="toc_Tapes" href="#Tapes">6 Using <code>gzip</code> on tapes</a>
+<li><a name="toc_Problems" href="#Problems">7 Reporting Bugs</a>
+<li><a name="toc_Concept-Index" href="#Concept-Index">Concept Index</a>
+</li></ul>
+</div>
+
+</body></html>
+