How to tar/untar

tar is used to create a Tape ARchive.  The resulting file is known as a tarball.  It's pretty much the same concept as a ZIP file, if you know what they are, but without the compression.  To get the files out of a tarball, you can use the following commands:

    tar xvf something.tar 
If the tarball has also been gzipped (compressed), you can use the following command:

   tar xvfz something.tar.gz

If you only want certain directories from the tarball, do this:

  tar xvzf something.tar.gz */dir.you.want/*

If you have a .tar.bz2 file, then you need bzip2 installed (/usr/ports/archivers/bzip2), and you issue this command:

 tar yxf something.tar.bz2 
To tar up *.db in the current directory into a tarball called blah.tar.gz, issue this command:

    tar cfz blah.tar.gz *.db

The z option compresses.
listing the contents
To see a list of the files within a tarball, issue the following command:

    tar -tzf blah.tar.gz

The -t provides a list.  the -z indicates that the tarball is compressed.   The -f identifies the tarball.

Here's an example: 
    # tar -tzf makeworld.991126.tgz
    etc/
    etc/protocols
    etc/aliases
    etc/services
    etc/hosts