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+<title>tar</title>
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+<link rel="HOME" title="Slackware Linux Essentials" href="index.html" />
+<link rel="UP" title="Archive Files" href="archive-files.html" />
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+<table summary="Header navigation table" width="100%" border="0" cellpadding="0"
+cellspacing="0">
+<tr>
+<th colspan="3" align="center">Slackware Linux Essentials</th>
+</tr>
+
+<tr>
+<td width="10%" align="left" valign="bottom"><a href="archive-files-bzip2.html"
+accesskey="P">Prev</a></td>
+<td width="80%" align="center" valign="bottom">Chapter 15 Archive Files</td>
+<td width="10%" align="right" valign="bottom"><a href="archive-files-zip.html"
+accesskey="N">Next</a></td>
+</tr>
+</table>
+
+<hr align="LEFT" width="100%" />
+</div>
+
+<div class="SECT1">
+<h1 class="SECT1"><a id="ARCHIVE-FILES-TAR" name="ARCHIVE-FILES-TAR">15.3 <tt
+class="COMMAND">tar</tt></a></h1>
+
+<p><tt class="COMMAND">tar</tt>(1) is the GNU tape archiver. It takes several files or
+directories and creates one large file. This allows you to compress an entire directory
+tree, which is impossible by just using <tt class="COMMAND">gzip</tt> or <tt
+class="COMMAND">bzip2</tt>. <tt class="COMMAND">tar</tt> has many command line options,
+which are explained in its man page. This section will just cover the most common uses of
+<tt class="COMMAND">tar</tt>.</p>
+
+<p>The most common use for <tt class="COMMAND">tar</tt> is to decompress and unarchive a
+package that you've downloaded from a web site or ftp site. Most files will come with a
+<tt class="FILENAME">.tar.gz</tt> extension. This is commonly known as a
+&#8220;tarball&#8221;. It means that several files were archived using <tt
+class="COMMAND">tar</tt> and then compressed using <tt class="COMMAND">gzip</tt>. You
+might also see this listed as a <tt class="FILENAME">.tar.Z</tt> file. It means the same
+thing, but this is usually encountered on older Unix systems.</p>
+
+<p>Alternatively, you might find a <tt class="FILENAME">.tar.bz2</tt> file somewhere.
+Kernel source is distributed as such because it is a smaller download. As you might have
+guessed, this is several files archived with <tt class="COMMAND">tar</tt> and then
+bzipped.</p>
+
+<p>You can get to all the files in this archive by making use of <tt
+class="COMMAND">tar</tt> and some command line arguments. Unarchiving a tarball makes use
+of the <var class="OPTION">-z</var> flag, which means to first run the file through <tt
+class="COMMAND">gunzip</tt> and decompress it. The most common way to decompress a
+tarball is like so:</p>
+
+<table border="0" bgcolor="#E0E0E0" width="100%">
+<tr>
+<td>
+<pre class="SCREEN">
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">tar -xvzf filename.tar.gz</kbd>
+</pre>
+</td>
+</tr>
+</table>
+
+<p>That's quite a few options. So what do they all mean? The <var class="OPTION">-x</var>
+means to extract. This is important, as it tells <tt class="COMMAND">tar</tt> exactly
+what to do with the input file. In this case, we'll be splitting it back up into all the
+files that it came from. <var class="OPTION">-v</var> means to be verbose. This will list
+all the files that are being unarchived. It is perfectly acceptable to leave this option
+off, if somewhat boring. Alternatively, you could use <var class="OPTION">-vv</var> to be
+very verbose and list even more information about each file being unarchived. The <var
+class="OPTION">-z</var> option tells <tt class="COMMAND">tar</tt> to run <tt
+class="FILENAME">filename.tar.gz</tt> through <tt class="COMMAND">gunzip</tt> first. And
+finally, the <var class="OPTION">-f</var> option tells <tt class="COMMAND">tar</tt> that
+the next string on the command line is the file to operate on.</p>
+
+<p>There are a few other ways to write this same command. On older systems lacking a
+decent copy of GNU <tt class="COMMAND">tar</tt>, you might see it written like so:</p>
+
+<table border="0" bgcolor="#E0E0E0" width="100%">
+<tr>
+<td>
+<pre class="SCREEN">
+<samp class="PROMPT">%</samp> <kbd
+class="USERINPUT">gunzip filename.tar.gz | tar -xvf -</kbd>
+</pre>
+</td>
+</tr>
+</table>
+
+<p>This command line will uncompress the file and send the output to <tt
+class="COMMAND">tar</tt>. Since <tt class="COMMAND">gzip</tt> will write its output to
+standard out if told to do so, this command will write the decompressed file to standard
+out. The pipe then sends it to <tt class="COMMAND">tar</tt> for unarchiving. The
+&#8220;-&#8221; means to operate on standard input. It will unarchive the stream of data
+that it gets from <tt class="COMMAND">gzip</tt> and write that to the disk.</p>
+
+<p>Another way to write the first command line is to leave off the dash before the
+options, like so:</p>
+
+<table border="0" bgcolor="#E0E0E0" width="100%">
+<tr>
+<td>
+<pre class="SCREEN">
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">tar xvzf filename.tar.gz</kbd>
+</pre>
+</td>
+</tr>
+</table>
+
+<p>You might also encounter a bzipped archive. The version of <tt
+class="COMMAND">tar</tt> that comes with Slackware Linux can handle these the same as
+gzipped archives. Instead of the <var class="OPTION">-z</var> command line option, you'd
+use <var class="OPTION">-j</var>:</p>
+
+<table border="0" bgcolor="#E0E0E0" width="100%">
+<tr>
+<td>
+<pre class="SCREEN">
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">tar -xvjf filename.tar.bz2</kbd>
+</pre>
+</td>
+</tr>
+</table>
+
+<p>It is important to note that <tt class="COMMAND">tar</tt> will place the unarchived
+files in the current directory. So, if you had an archive in <tt
+class="FILENAME">/tmp</tt> that you wanted to decompress into your home directory, there
+are a few options. First, the archive could be moved into your home directory and then
+run through <tt class="COMMAND">tar</tt>. Second, you could specify the path to the
+archive file on the command line. Third, you can use the <var class="OPTION">-C</var>
+option to &#8220;explode&#8221; the tarball in a specified directory.</p>
+
+<table border="0" bgcolor="#E0E0E0" width="100%">
+<tr>
+<td>
+<pre class="SCREEN">
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">cd $HOME</kbd>
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">cp /tmp/filename.tar.gz .</kbd>
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">tar -xvzf filename.tar.gz</kbd>
+
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">cd $HOME</kbd>
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">tar -xvzf /tmp/filename.tar.gz</kbd>
+
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">cd /</kbd>
+<samp class="PROMPT">%</samp> <kbd
+class="USERINPUT">tar -xvzf /tmp/filename.tar.gz -C $HOME</kbd>
+</pre>
+</td>
+</tr>
+</table>
+
+<p>All the above statements are equivalent. In each case, the archive is unpacked inside
+your home directory and the original uncompressed archive is left in place.</p>
+
+<p>So what good is being able to uncompress these archives if you can't make them? Well,
+<tt class="COMMAND">tar</tt> handles that too. In most cases it's as easy as removing the
+&#8220;<var class="OPTION">-x</var>&#8221; option and replacing it with the &#8220;<var
+class="OPTION">-c</var>&#8221; option.</p>
+
+<table border="0" bgcolor="#E0E0E0" width="100%">
+<tr>
+<td>
+<pre class="SCREEN">
+<samp class="PROMPT">%</samp> <kbd class="USERINPUT">tar -cvzf filename.tar.gz .</kbd>
+</pre>
+</td>
+</tr>
+</table>
+
+<p>In this command line, the <var class="OPTION">-c</var> option tells <tt
+class="COMMAND">tar</tt> to create an archive, while the <var class="OPTION">-z</var>
+option runs the resulting archive file through <tt class="COMMAND">gzip</tt> to compress
+it. <tt class="FILENAME">filename.tar.gz</tt> is the file that you want to create.</p>
+
+<p>Specifying the &#8220;<var class="OPTION">-f</var>&#8221; option isn't always
+necessary, but is typically good practice anyway. Without it, <tt
+class="COMMAND">tar</tt> writes to standard output, which is usually desired for piping
+<tt class="COMMAND">tar</tt>'s output to another program, like so.</p>
+
+<table border="0" bgcolor="#E0E0E0" width="100%">
+<tr>
+<td>
+<pre class="SCREEN">
+<samp class="PROMPT">%</samp> <kbd
+class="USERINPUT">tar -cv filename.tar . | gpg --encrypt</kbd>
+</pre>
+</td>
+</tr>
+</table>
+
+<p>That command creates an non-compressed tar archive of the current directory, pipes the
+tarball through <tt class="COMMAND">gpg</tt> which encrypts and compresses the tarball,
+making it realistically impossible to read by anyone other than the person knowing the
+secret key.</p>
+</div>
+
+<div class="NAVFOOTER">
+<hr align="LEFT" width="100%" />
+<table summary="Footer navigation table" width="100%" border="0" cellpadding="0"
+cellspacing="0">
+<tr>
+<td width="33%" align="left" valign="top"><a href="archive-files-bzip2.html"
+accesskey="P">Prev</a></td>
+<td width="34%" align="center" valign="top"><a href="index.html"
+accesskey="H">Home</a></td>
+<td width="33%" align="right" valign="top"><a href="archive-files-zip.html"
+accesskey="N">Next</a></td>
+</tr>
+
+<tr>
+<td width="33%" align="left" valign="top"><tt class="COMMAND">bzip2</tt></td>
+<td width="34%" align="center" valign="top"><a href="archive-files.html"
+accesskey="U">Up</a></td>
+<td width="33%" align="right" valign="top"><tt class="COMMAND">zip</tt></td>
+</tr>
+</table>
+</div>
+</body>
+</html>
+