Although Apple Computer ushered in the PC revolution in 1980 with the Apple II computer, the inventions that are most synonymous with the company are the Macintosh computer and its ground-breaking graphical operating system, both released in 1984. Let's think of this operating system as Mac OS 1, though Apple wouldn't coin the term "Mac OS" to describe its operating system until the 1990s. The early Mac made its mark in a world where all other popular computer interfaces were obscure.
In the years following the Mac's release, much has changed. Both bad and good things have happened, and some company in Washington called Microsoft started to take over the world. By 1996, Apple knew it needed to modernize the Mac OS (and make it more worthy competition to Windows) from the bottom up, but previous attempts and partnerships to bring this about had ended in failure. So, Apple made an unusual move and purchased NeXT. This company had made a nice Unix-based operating system called NeXTSTEP, in which Apple saw the seeds of its own salvation. As it happened, NeXT's leader was the ambitious Steve Jobs, one of Apple's founders, who left the company after a political rift in the 1980s. To make a long and interesting story short, Jobs quickly seized control of Apple Computer, stripped it down to its essentials, and put all its resources into reinventing the Mac. Five years later, the result was Mac OS X: a computing platform based around an entirely new operating system that merged the best parts of the old Mac OS, NeXTSTEP, and nearly two decades of user feedback on the Mac OS.
Mac OS X initially may seem a little alien to long-time Mac users; it is, quite literally, an entirely different operating system from Mac OS 9 and earlier versions (even though Mac OS X retains most of its predecessor's important interface idioms, such as the way the desktop and the user interface works). However, the Mac is now winning more converts than ever, not just from Windows, but from other Unix systems such as Linux, Solaris, and FreeBSD (from which Mac OS X's Unix core is derived).
Mac OS X brings all of the great things from earlier versions of the Mac OS and melds them with a BSD core, bringing Unix to the masses. Apple has created a rock-solid operating system to compete both on the user and enterprise level. In days gone by, the Mac was mostly looked at as a system for "fluffy-bunny designers." It's now becoming the must-have hardware and operating system of geeks and designers everywhere.
With Mac OS X, you can bring home the bacon and fry it up in a pan. Your Mac can be used not only for graphic design and creating web pages, but also as a web server. Not into flat graphics? Fine, Mac OS X sports Quartz Extreme and OpenGL. Want to learn how to program? Mac OS X is a developer's dream, packing in Perl, Python, Ruby, C, C++, Objective-C, compilers, and debuggers; if you're an X jockey, you can also run the X Window System on top of Mac OS X using Apple's X11 distribution or with other installations of XFree86. In addition to the standard programming languages, Mac OS X comes with a powerful set of frameworks for programming with Cocoa, Mac OS X's native language (adopted from NeXT).
This book should be of interest to Unix users and Unix programmers, as well as to anyone (such as a system administrator) who might offer direct support to users and programmers. The presentation is geared mainly toward people who are already familiar with the Unix system; that is, you know what you want to do, and you even have some idea how to do it. You just need a reminder about the details. For example, if you want to remove the third field from a database, you might think, "I know I can use the cut command, but what are the options?" In many cases, this book provides specific examples to show how a command is used.
This reference might also help people who are familiar with some aspects of Unix but not with others. Many chapters include an overview of the particular topic. While this isn't meant to be comprehensive, it's usually sufficient to get you started in unfamiliar territory.
Finally, if you're new to the Unix side of Mac OS X, and you're feeling bold, you might appreciate this book as a quick tour of what Unix has to offer. Chapter 1 can point you to the most useful commands, and you'll find brief examples of how to use them, but take note: this book should not be used in place of a good beginner's tutorial on Unix. For that, you might try O'Reilly's Learning Unix for Mac OS X Tiger. This reference should be a supplement, not a substitute. (There are references throughout the text to other relevant O'Reilly books that will help you learn the subject matter under discussion; in some cases, you may be better off detouring to those books first.)