How do I undo a .tar.gz file?

Well, the first thing to do is type man tar. This gives you all the options for tar, much like you'd expect.

To get you started, here are some common invocations to help you untar the tar manpage, which you will no doubt read as soon as possible.

• To untar something that's in ``.tar.gz'' format, try tar xvzf [filename].
• To untar something that's in ``.tar.Z'' format, try tar xvZf [filename]. Note the capitalized Z.
• bzip2 files are slightly more problematic. Try tar -use-compress-program=bunzip2 -xvf [filename] for these. Earlier versions of tar also understood the -I flag for bzip2 archibes, nowadays it's the -j flag. Just read the manual page for your version of tar, and you'll be fine.