Chapter 24: Commanding Unix

Mac OS X is built upon a foundation known as Darwin. Apple has made the source to Darwin downloadable on the Internet. Darwin integrates several key technologies including the Mach kernel and services based on BSD Unix. Above Darwin is the Aqua user interface that provides the OS X user experience.

This Chapter presents a brief history of Unix and shows you how to use some of its power. Unix is a mature operating system with literally hundreds of commands. You never really need to see many of these commands; however, if your curiosity gets the better of you, this Chapter points you to some excellent Unix references.

Introduction to Unix

Unix was developed at Bell Laboratories in 1969. It was designed to be a multiuser operating system. The prevalent computers of the time were mainframe systems. On these systems, a single user at a time could use the computing resources made available by creating programs on punch cards and feeding them to the system, then awaiting the output of the program on a nearby printer. This system tended to isolate programmers and users from each other and additionally provided no facility to save data. Unix was designed from the ground up to overcome these and other obstacles. In addition to providing access to more than one program or person at a time, Unix was designed to be interactive, providing output via a terminal or console rather than a printer. Unix went thru many revisions in the 1970s and 1980s. AT&T was prohibited by law from selling computers or software at that time; instead, it granted licenses to many universities, where deployment and development rapidly took place. Even Apple produced a Unix-based system for its Macintosh line, A/UX (Apple Unix), in the late 1980s and early 1990s. Additionally, the NeXT operating system, acquired by Apple with the purchase of NeXT, is a Unix-based operating system. Much of the original NeXTStep or OpenStep operating system concepts are present in Mac OS X.

A standard Unix implementation includes a large variety of commands that enable users to perform a multitude of operations, from editing text to creating multimedia, providing and utilizing network services, and everything in between. Most software one would expect to see on a modern desktop computer is available, including a word processor, Web browser, email client, games, and more.