Nowadays tar is used as a convient way to transfer programs across the internet, while keeping the directory structure intact. Extracts the contents of util.tar into the PWD grep Grep is the neatest of all utilities. The purpose of grep is to find regular expressions and report them back to the user. A good introduction to regular expressions can be found in the man pages for grep. Most programs for linux are distributed with source.
Online documentation Learn to use man pages, although obtuse at times, they really are useful.
At the end of each man page, if there is any related material, there will be a see also. Info pages are available for gcc, just type info. These utilities are useful when dealing with process. Also shows how much free memory is available, and how busy, as a whole, the cpu currently is. Ps is used to find out what programs are being run.