Renowned for its friendliness, Mac OS X has delighted many a loyal Mac user with its combined ease use and underlying strength. By no means simplistic, its intelligently designed operating system and user interface boast of sophistication and power, while still offering accessibility to even the most inexperienced computer users. But Mac OS X has gone one step further: it's turned unsuspecting Mac users into Unix users, too.Perhaps you're already familiar with Unix, just not on the Mac. Or perhaps you opened your Utilities folder, spotted the Terminal icon and double-clicked on it just to see what it does. Suddenly faced with a command line interface, you may have asked, "What does this mean?" followed by the most pressing question, "W...