CLIX The Cocoa application, "Command Line Interface for OS X", harnesses Unix's power. It's great for professionals, but can also be useful for beginners.
The CLIX package comes with a starter database file that contains over 1,100 system commands. This allows you to investigate your system status, clean out junk files, and find esoteric secrets settings in your most frequently used applications.
CLIX is also infinitely extensible. You can add new commands, command categories, command database files, etc.
CLIX, unlike other systems is 100% 'WYSISYG (what you see is exactly what you get): It's exactly the same command lines that you would use at a terminal. You might be able to recall a few commands and then try them on your own.
CLIX has many commands that allow you to view all your system logs.
CLIX also offers a newsletter and command exchange that allow for in-depth discussion about Unix and CLIX commands.
Keep your Mac safe and secure.