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diff --git a/chapter_04.xml b/chapter_04.xml index 794113e..96cb46c 100644 --- a/chapter_04.xml +++ b/chapter_04.xml @@ -457,9 +457,100 @@ So great, we know how to compress files using all sorts of programs, but none of them can archive files in the way that <application>zip</application> does. That is until now. The Tape Archiver, or <application>tar</application>(1) is the most frequently -used archival program in Slackware. +used archival program in Slackware. Like other archival programs, +<application>tar</application> generates a new file that contains other +files and directories. It does not compress the generated file (often +called a "tarball") by default; however, the version of +<application>tar</application> included in Slackware supports a variety +of compression schemes, including the ones mentioned above. </para> +<para> +Invoking <application>tar</application> can be as easy or as +complicated as you like. Typically, creating a tarball is done with the +<arg>-cvzf</arg> arguments. Let's look at these in depth. +</para> + +<table pgwide="0" frame="none"> +<title>tar Arguments</title> +<tgroup cols="2"> + <thead> + <row> + <entry>Argument</entry> + <entry align="right">Meaning</entry> + </row> + </thead> + <tbody> + <row> + <entry>c</entry> + <entry align="right">Create a tarball</entry> + </row> + <row> + <entry>x</entry> + <entry align="right">Extract the contents of a tarball</entry> + </row> + <row> + <entry>t</entry> + <entry align="right">Display the contents of a tarball</entry> + </row> + <row> + <entry>v</entry> + <entry align="right">Be more verbose</entry> + </row> + <row> + <entry>z</entry> + <entry align="right">Use gzip compression</entry> + </row> + <row> + <entry>j</entry> + <entry align="right">Use bzip2 compression</entry> + </row> + <row> + <entry>J</entry> + <entry align="right">Use LZMA compression</entry> + </row> + <row> + <entry>p</entry> + <entry align="right">Preserve permissions</entry> + </row> + </tbody> +</tgroup> +</table> + +<para> +<application>tar</application> requires a bit more precision than other +applications in the order of its arguments. The <arg>-f</arg> argument +must be present when reading or writing to a file for example, and the +very next thing to follow must be the filename. Consider the following +examples. +</para> + +<screen><prompt>darkstar:~$ </prompt><userinput>tar -xvzf /tmp/tarball.tar.gz</userinput> +<prompt>darkstar:~$ </prompt><userinput>tar -xvfz /tmp/tarball.tar.gz</userinput></screen> + +<para> +Above, the first example works as you would expect, but the second +fails because <application>tar</application> has been instructed to +open the <filename>z</filename> file rather than the expected +<filename>/tmp/tarball.tar.gz</filename>. +</para> + +<para> +Now that we've got our arguments straightened out, lets look at a few +examples of how to create and extract tarballs. As we've noted, the +<arg>-c</arg> argument is used to create tarballs and <arg>-x</arg> +extracts their contents. If we want to create or extract a compressed +tarball though, we also have to specify the proper compression to use. +Naturally, if we don't want to compress the tarball at all, we can +leave these options out. The following command creates a new tarball +using the <application>gzip</application> compression alogrithm. While +it's not a strict requirement, it's also good practice to add the .tar +extension to all tarballs as well as whatever extension is used by the +compression algorithm. +</para> + +<screen><prompt>darkstar:~$ </prompt><userinput>tar -czf /tmp/tarball.tar.gz /tmp/tarball/</userinput></screen> + </section> </section> |