Dave Taylor - Learning Unix for OS X Mountain Lion: Using Unix and Linux Tools at the Command Line

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Its been a long time since we went through the dramatic transition from Mac OS 9 to the more complicated and graphically rich world of OS X. Many of you reading this have never known a Mac interface that wasnt actually OS X (pronounce that oh-ess ten to sound cool). The biggest change when Apple switched operating systems was that every machine then gained multitasking and multiuser capabilities.

What you might not have realized, however, is that it was the underlying operating system itself that changed in the update to OS X, and that you now have a tremendously powerful OS that can run thousands of open source applications downloaded free from the Net, along with a command-line interface that makes even the most complex tasks a breeze.

If you want to learn the key phrases, beneath OS X lies an operating system called Unix (pronounced you-nicks): specifically, UC Berkeleys BSD Unix and the Mach kernel, a multiuser, multitasking operating system. Being multiuser means OS X allows multiple users to share the same system, each with their own settings, preferences, and separate area in the filesystems, secured from other users prying eyes. Being multitasking means OS X can easily run many different applications at the same time, and if one of those applications crashes or hangs, the entire system doesnt need to be rebooted. Instead, you just force quit the application thats causing the Spinning Beach Ball of Death (you know, when the mouse pointer turns into a spinning color wheel that just wont stop rotating) and either relaunch it or proceed with your work in other apps.

The fact that OS X has Unix under the hood doesnt matter to users who simply want to use its slick graphical interface to run their applications or manage their files. But it opens up a world of possibilities for users who want to dig a little deeper. The Unix command-line interface, which is accessible through the Terminal application ( /Applications/Utilities ), provides an enormous amount of power for intermediate and advanced users. Whats more, once youve learned to use Unix in OS X, youll also be able to use the command line in other versions of Unix, such as FreeBSD (from which OS X derives its Unix core) or even the hugely popular Linux.

This book is designed to teach Mac users the basics of Unix. Youll learn how to use the command line (which Unix users refer to as the shell ) and the filesystem, as well as some of Unixs most useful commands. Ill also give you a tour of some useful Unix commands that Apples team have written and include with every Mac systemutilities that let you really gain control over your system. Unix is a complex and powerful system, so I can only scratch the surface, but Ill also tell you how to deepen your Unix knowledge once youre ready for more.