If using CUIT's CUNIX systems or firing up the Terminal application on your Mac gives you the willies, then check out the FLOSS Manuals Foundation's excellent introduction to Unix commands. The manual is a thorough but fun introduction to Unix commands covering basics but quickly reaches simple methods for leveraging the power of commands. The manual is called Command Line and is available in HTML and PDF formats. Beginners will find numerous tips and experienced users should find the advanced features worthwhile. The manual also includes brief introductions to a number of Unix text editors, regular expressions, and shell scripting.