Unix and the Mac

An Introduction to Unix

- 2002.01.29

The world of IT (information Technology) is being swept by the Unix* phenomenon. The magazines say so, and the Internet agrees.

Though the Unix operating system first came to the attention of most Mac users through it's use as the core of Mac OS X, other sections of the computing community - particularly among the Intel-based crowd - have had a head start via Linux, a popular, often-free version of Unix sometimes touted as a "Microsoft killer."

Interestingly, for an operating system which has generated so much publicity only recently, Unix is quite possibly the oldest still-published operating system around. It hails from the same age as the moon-landings - development started at AT&T's Bell Labs in 1969 (see The Creation of the Unix Operating System for a brief history).

In the meantime, Unix has sat silently in the background running much of the Internet, the world's telephone systems, and a myriad of other high-demand and often critical tasks. It did so beautifully, before being swept to public view by the startling popularity of such free variants of itself as Linux and FreeBSD.

So what make Unix stand out from, say, the Mac OS (prior to OS X) or Windows? And just what is it all about anyway?

One of the more bewildering aspects of Unix is that you can't walk into your nearest computer superstore and pick up a copy of, say, "Unix 11.7" fresh off the shelf. Rather, Unix has fragmented into a melee of derivatives, clones, and work-a-likes - ranging from the now familiar Mac OS X, commercial heavyweights such as Silicon Graphic's IRIX and IBM's AIX, and free "home-brew" systems such as the perennial Linux or the ultra-secure OpenBSD.

This fragmentation dates back from the earliest days of the Unix Time-Sharing System, as it was then known. At the time, AT&T was prohibited from selling it's new OS, so it chose to distribute it at minimal cost to universities.

Universities have a well-deserved reputation as hotbeds of technical innovation, so it came as no surprise when they took this new system and worked it into new forms - adding functionality here, optimizing something there. Not only did AT&T's generosity accelerate the development of it's new system (albeit at the price of standardization), but it also ensured that there was a large pool of technicians available who were well-versed in Unix from their university days.

As these students went out into the industry, they took their knowledge with them, ensuring Unix a place at firms such as Digital Equipment, Sun Microsystems, and Hewlett Packard, each of which developed their own version of the OS to suit their own machines and markets. Some control over all these differing versions is offered by POSIX - a standard to which all Unix variants have to comply to qualify as "Unix." Just because all these systems qualify as Unix, however, doesn't mean that there aren't differences between them. Unix comes with a bewildering array of "shells" (programs that provide the command line interfaces) and even more graphical front-ends - ranging from Mac OS X's sumptuous Aqua to the KDE Desktop usually associated Linux - each with enough differences to ensure that knowing one doesn't necessarily mean you know them all.

The strengths of Unix over most other operating systems are easy to list.

First off it offers excellent multitasking, with an industrial-strength implementation of protected-memory - if one program crashes, it can't bring the entire system down to its knees. Also, badly written programs cannot overwrite another program's memory space, hanging the system. Indeed it is very difficult for a program or user to bring down an entire Unix system.

Unix's multitasking is preemptive - it allocates resources to programs as it sees fit and even allows you to set priority between various running programs. This is a marked departure from the "cooperative multitasking" system used in operating systems such as Mac OS 9 and earlier, which depends on programs being well behaved and not hogging the CPU.

Unix is also a multi-user operating system. Hundreds of people can log into a single Unix server, and each can interact with it just as if they were sitting in front of its keyboard and mouse - you can even do this with a Unix system on the other side of the world via the Internet.

This points to Unix's other great strength - networking. Unix natively supports the TCP/IP protocol that drives the Internet, which is one of the reasons why the majority of the world's Internet servers are Unix machines. The operating system was built with networking in mind more or less from day one, with the emphasis being on speed, support, and reliability.

It is possible to hook a Unix box up to an IPX or AppleTalk network, and the system can even support such obscure networking protocols as Acorn's Econet.

As you can imagine from an OS used in so many mission critical applications, Unix is very, very robust. While Windows boxes can crash on a daily basis, and even a Macintosh running a pre-X OS needs to be restarted regularly if you open and close many programs, Unix can go for months between reboots. Indeed, one of the main causes for downtime on Unix servers is power outages.

Unix has a reputation for being complex and unwieldy in use, and, for some part, it is a well-deserved one. It has been added to by countless people, each with their own ideas of program design and how things should work. This means that the conventions used in one program will not necessarily carry over to another.

More intimidating from the point of view of many Mac users (and Windows junkies, for that matter) is that Unix is primarily a character-driven OS - you type sometimes cryptic commands at a text prompt as you would with MS-DOS. While this initially puts many off, any version of Unix you are likely to encounter will include support for the X-Windows system, which provides semi-familiar graphical front end to the OS.

As I mentioned, Unix vendors are free to design their own GUIs, and some versions can put dedicated graphical OSes to shame. With a modern Unix variant such as Mac OS X,or Linux with KDE 2.x, there is often no need to touch the command line, though your Unix education would be poorer for it.

There are plenty of commercial applications available for Unix. For the most part, these tended to be biased towards the server market or to a specific hardware/Unix combination. For instance, a Silicon Graphics workstation has a number of image, video, and 3D editing programs available to take advantage of it's sheer A/V power and role in motion picture special effects creation.

Where there has been a traditional shortage of applications, however, is in the productivity realm. Unix systems have traditionally been aimed at the server and high-end workstation markets, not towards the home or office worker. This has begun to change with the surge in popularity of Linux, and there are now word processors, office suites, image editors, and many, many other applications to choose from. Better yet is the price - many are free.

But is Unix right for you? If you are reading this, it's almost certain that one day you will find yourself eye-to-eye with the Mac OS X desktop.

Should you try your hand at Linux, NetBSD, et al? That depends on you. If your curious enough about these OSes to be contemplating installing them, then chances are that you'll have something to gain from taking the plunge.

Unix skills (of the sort you don't get burning CDs with iTunes in OS X) are highly sought after in today's workforce. With an Open Source Unix such as Linux, you can learn what makes the OS - including the Mac running OS X - tick at a fundamental level. You can even write some code, offer it up to the Open Source community, and have it incorporated into your favorite free Unix.

Generally, if you're looking for a powerful, infinitely customizable OS that can be molded to perform just about any task you can imagine, or if you're just a geek who loves playing around with big, powerful, complex things, you'll likely find Unix a rewarding adventure. LEM

* Unix is a registered trademark of The Open Group. Different people have different view as to what constitutes Unix, and purists often use the term "*nix" to cover Unix, Linux, BSD, etc. We think that's ugly (as is typing "UNIX" in all caps) and believe any Unix-like OS derived from the work of Bell Labs - including the various BSD (Berkeley Software Distributions) versions. (See Twenty Years of Berkeley Unix: From AT&T-Owned to Freely Redistributable for information on how entire parts of Unix were developed at Berkeley, not Bell Labs). Because of this intertwined history between AT&T Unix and BSD Unix, we believe both are equally deserving of the Unix name, and this is how we tend to use it on Low End Mac. Dan Knight, publisher.

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