There are many compressing commands in UNIX/Linux: zip/unzip,gzip/gunzip,compress/uncompress,pax and so on...
Even tar command now knows to compress, for example
like tar -cvzf myarchive.tar.Z /somedirectory so there is no need to perform
compression as it does it automatically with "z" option added.

Hope it helps.

Get "UNIX in 24 hours" book or "UNIX Essentials and UNIX Core" DVD as they explain stuff like that.