This book was written primarily with two audiences in mind:
Beginners who have never or barely used Unix before.
You are the folks who we expect will actually read and use this book. We don't expect you to know anything at all about Unix before you read the book (but you will know a great deal about it when you are done). We'll teach you all the basic Unix skills and provide you with a solid reference book to turn to in the future. If you start at the beginning (often a good idea!) and work your way through, this book will give you an excellent foundation in Unix.
We assume that you are adventurous, creative, and curious (hey, you are a Mac user , after all). We also assume that you have experience with the Macintosh and have become comfortable with the Aqua interface introduced in Mac OS X. If you are new to Mac OS X, we suggest that you also read Peachpit Press's Mac OS X Tiger: Visual QuickStart Guide , by Maria Langer (Peachpit Press; www.peachpit.com).
Expert Unix users.
You have installed and configured Unix systems in your sleep. You know the differences between the System V and BSD versions of the ps command. You have a favorite in the vi versus emacs debate. Your Unix-novice Mac-using friends keep calling you for help with cd and ls .
If you already know your way around Unix, the simple fact is that you already know your way around 90 percent of Unix on Mac OS X. As we describe in Chapter 1, Mac OS X includes a complete Unix system, Darwin, that is based mostly on FreeBSD 4.4 and that you can use just like any other Unix system. Yes, there are a few differences ( marked in this book with the Darwin mascot, Hexley), but mostly it's the same as other Unix systems you have used.
We hope you'll buy this book by the case-load and give copies to friends who are new to Unix, so that they'll stop pestering you with basic questions.