<<Anchor(faq56)>>
== How can I untar (or unzip) multiple tarballs at once? ==
As the {{{tar}}} command was originally designed to read from and write to tape devices (tar - Tape ARchiver), you can specify only filenames to put inside an archive (write to tape) or to extract out of an archive (read from tape).

There is an option to tell {{{tar}}} that the archive is not on some tape, but in a file: {{{-f}}}. This option takes exactly one argument: the filename of the file containing the archive. All other (following) filenames are taken to be archive members:
{{{
    tar -x -f backup.tar myfile.txt
    # OR (more common syntax IMHO)
    tar xf backup.tar myfile.txt
}}}

Now here's a common mistake -- imagine a directory containing the following archive-files you want to extract all at once:
{{{
    $ ls
    backup1.tar backup2.tar backup3.tar
}}}

Maybe you think of {{{tar xf *.tar}}}. Let's see:
{{{
    $ tar xf *.tar
    tar: backup2.tar: Not found in archive
    tar: backup3.tar: Not found in archive
    tar: Error exit delayed from previous errors
}}}

What happened? The shell replaced your `*.tar` by the matching filenames.  You really wrote:
{{{
    tar xf backup1.tar backup2.tar backup3.tar
}}}

And as we saw earlier, it means: "extract the files backup2.tar and backup3.tar from the archive backup1.tar", which will of course only succeed when there are such filenames stored in the archive.

The solution is relatively easy: extract the contents of all archives '''one at a time'''. As we use a UNIX shell and we are lazy, we do that with a loop:
{{{
    for tarname in ./*.tar; do
      tar xf "$tarname"
    done
}}}

What happens? The for-loop will iterate through all filenames matching {{{*.tar}}} and call {{{tar xf}}} for each of them. That way you extract all archives one-by-one and you even do it automagically.

The second common archive type in these days is ZIP. The command to extract contents from a ZIP file is {{{unzip}}} (who would have guessed that!). The problem here is the very same: {{{unzip}}} takes only one option specifying the ZIP-file. So, you solve it the very same way:
{{{
    for zipfile in ./*.zip; do
      unzip "$zipfile"
    done
}}}

Not enough? Ok. There's another option with {{{unzip}}}: it can take shell-like patterns to specify the ZIP-file names. And to avoid interpretation of those patterns by the shell, you need to quote them. {{{unzip}}} itself and '''not''' the shell will interpret {{{*.zip}}} in this case:
{{{
    unzip "*.zip"
    # OR, to make more clear what we do:
    unzip \*.zip
}}}

(This feature of {{{unzip}}} derives mainly from its origins as an MS-DOS program.  MS-DOS's command interpreter does not perform [[glob]] expansions, so every MS-DOS program must be able to expand wildcards into a list of filenames.  This feature was left in the Unix version, and as we just demonstrated, it can occasionally be useful.)