AIX

Another UNIX contender is IBM's AIX. AIX's main claim to fame is the journaling filesystem, which records all disk transactions as they happen. It allows you to recover from system crashes without much trouble, providing great reliability. AIX is based largely on BSD.

Linux

Linux is a clone of UNIX, written from the ground up in the last decade or so. Linux is similar to BSD in many ways, though BSD has a much longer heritage, and is more friendly to commercial use than Linux. Linux includes a requirement that a commercial user contribute all changes back to Linux, while BSD has no such restriction.

Among many UNIX users, there's a perception of conflict between the BSD and Linux camps. If you dig a little deeper, however, you'll find that most of the developers of these platforms communicate and cooperate in a friendly and open manner. It's just a hard fringe of users and a very few developers that generate friction.

IRIX, HPUX, etc.

Other UNIXes include Silicon Graphics' IRIX, a solid UNIX for graphics applications, and Hewlett−Packard's HP−UX, popular in large enterprises. Many high− end software packages, such as Informix, are specially designed for HP−UX.

If you look around you'll also find smaller contenders, such as SCO and UnixWare. They aren't unimportant, they just aren't as popular. You'll also find old castoffs, such as Apple's A/UX and Microsoft's Xenix. (Yes, Microsoft was a licensed UNIX vendor, very, very long ago.) Xenix was eventually sold to SCO and became SCO UNIX.

FreeBSD's Strengths

So, after all this, how can we summarize FreeBSD?

Portability

FreeBSD's goal is to provide a freely redistributable operating system that runs on popular hardware. While system security is a vital concern, FreeBSD's main goal is to run on the hardware people are most likely to have. Today, this means the Intel x86−compatible systems (386, 486, Pentium I through IV, Celeron, and AMD). FreeBSD also supports the Alpha processor, and work is underway to support Intel's new IA64, AMD's new 64−bit chips, and Motorola's PowerPC, as well as Sun's SPARC. (These platforms aren't afterthoughts; the hardware is just now coming out, or only now becoming popular enough to port to.)

Power

Since FreeBSD runs adequately on 386 hardware, it runs quite well on modern computers. It's rather nice to have an operating system that doesn't demand a Pentium III and a half−gig of RAM just to power the user interface. As a result, you can actually use all that computing power to do the work you want, rather than to run tasks you don't care about. If you choose to run a pretty graphical interface with all sorts of spinning geegaws and fancy whistles, FreeBSD will support you, it just

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