Unix for the Mac
With all the sudden interest surrounding Unix, in both its Open Source form and in the body of OS X, there couldn't be a better time to install a version of Unix on your Mac.
Before you do, though, there is one or two thing you should consider:
As a Mac user, you're no doubt aware that you are one of a minority. Though this is often of little consequence in the mainstream computing world, the Mac's limited user-base does raise some issues in the world of free Unix. Any free Unix you are likely to encounter is so for one reason - it is what's known as an "Open Source" operating system.
An Open Source program is one which is entirely in the public domain - all the programming code (in which it is written before being compiled into machine language) is out in the open for anyone to see, use, or modify. Operating systems written under this principle are crafted by the combined efforts of a legion of volunteers, almost all of whom are drawn from the user base of the very system they are creating. This instantly puts any minority system at a disadvantage, because the smaller the user-base, the smaller the number of skilled hands available to continually develop the system (remember also, that only a tiny portion of any Open Source OS' users actually have a hand in building it).
Also, it's probably fair to say that much of the Open Source community is drawn to the PC platform if only because people who write their own operating systems are likely to be the type who enjoy sifting through IRQ conflicts, fiddling with motherboard jumpers, and the other assorted delights of PC ownership. What this all boils down to is that updates, bug-fixes, documentation, and hardware support for Macintosh Unix systems can sometimes be less far-ranging and can lag behind their PC equivalents. This also means that many new bits of functionality for a given Unix clone will appear of the PC first, leaving the Mac community to wait their turn - occasionally in vain.
The disparity is often less noticeable than you might initially be led to believe, however, and the Mac teams tend to work on different priorities anyway. Still, this is an issue you should keep in the back of your mind, particularly if you like to constantly remain at the bleeding edge of new technology.
The sometimes-prolonged development lives of the various Mac Unix variants usually hits hardest when you first set up your machine as you run into the issue of hardware support. PC users often come out smiling: Almost any PC with an 80386 processor or better (i.e., any one made in the last decade or so) will be able to run a variant of pretty much any free Unix you can think of - FreeBSD, Linux, or OpenServer. They may run only a slow, minimalist version, but they will generally run.
Macintosh support for Unix is patchy in comparison. For example, OpenBSD will run on both 68k and "New World" Power Macs (those with a G3 or G4 processor), but those with, say, a Power Mac 7200 are out of luck. NuBus (x100 series) Power Macs can only run the "MkLinux" distribution. Macs such as the LC 475 that are built around the 68LC040 processor won't run any Unix version at all, due to a glitch in that processor's design, though you can usually get good results by swapping in a full 68040 processor.
Another obstacle in providing proper hardware support for Unix is Apple's historical unwillingness to release detailed information about its hardware. This means that even basic components of your Mac - such as the floppy drive and sound circuitry - may not work. Of course, if you're planning to turn your old IIcx into a router or whatever, whether or not you have sound support may be irrelevant, though it may still prove a nasty surprise to the unwary.
Generally, the newer your Mac, the less you suffer from this type of problem, but if you're looking at getting your hands around an old Mac for some Unix experimentation, be prepared to chose carefully. Also take care in selecting what hardware you use with your Mac. You'll find yourself having to pay attention when shopping for such items as network and video cards, as only some are supported. This is true of any platform, including the PC, but it can be felt more acutely by the Mac user given the already comparably limited pool of Mac hardware to begin with.
Much of the computing world's new found enthusiasm for Unix has been fueled by the steady stream of productivity applications that have now been released for the platform. Software such as Corel WordPerfect, Sun's Star Office, and Applixware have all helped elevate Unix to the level of a true competitor in the desktop market.
However, the fact that these programs run within Unix does not necessarily mean that they will run under Unix on a Macintosh - some developers chose to exclusively target the larger, more profitable band of PC users.
It's at this point that the distinction between open source and closed source software comes into focus. Closed source software is the type we're all familiar with - all the development work is handled by a company or person who then markets or distributes the software as a finished whole. You won't find any source code knocking about.
The main problem for users of minority Unix platforms such as the Mac is that what you see is what you get. If the developers choose not to support the Mac, then there is nothing you can do about it. In Open Source software, however, the source code itself is released (sometimes with a precompiled copy for simplicity). In this case, the user community is free to modify it to their own ends, which gives Mac users the freedom to set to work making it run on their computer of choice.
While few users have the time or skills to pick through and modify thousands of lines of C programming code, those who do often band together and make their Mac-friendly versions of Open Source software available to the public for free. Indeed, many good Unix distributions will have some Mac-compatible Open Source software thrown in.
What this boils down to is that while there is much good software available for a Mac running Unix, you might find some of your choices a bit more restricted than if you were running a majority system like the PC - a situation which mirrors that of the original Mac OS/Windows debate.
Another legacy of Apple's preference for closed, proprietary standards is the fact that the Macintosh was designed from day one to run the Mac OS exclusively, so when it comes to introducing a new operating system to the machine, things may not be as smooth as you'd expect.
Anyone used to loading a disk and simply executing a program in order to install a new operating system may be in for a nasty surprise. While most Unix systems incorporate such a capability across most platforms, some Macintosh Unix variants (like Debian Linux 68k) expect you to copy at least part of the system from the CD to you hard disk manually, and even if you do get an interactive installation, it may not be all it could be.
Just booting into your newly installed Unix system can also be somewhat of a hassle. Whereas PCs and dedicated Unix workstations can load a Unix system at startup, the Mac generally thinks only in terms of it's own native OS. This means that booting your Mac with Unix may involve first having to load the Mac OS and then manually startup the Unix OS, which then replaces it - a somewhat time consuming process.
Some Mac Unices, such as NetBSD for PowerPC, can be booted without having to first load the Mac OS, but these still require you to manually intervene and instruct the Mac to do so each time you startup.
Give It a Try
Though it may initially sound like your best option for dipping your toe into Unix would be to rush out and buy the first PC you see, using your trusty Mac may still make sense. Remember that the Open Source nature of these Unix variants means that they are being constantly refined and improved.
Also remember that the introduction of Mac OS X means that the Mac Unix community has come out with a vengeance. While some tasks can take some extra work, once setup and established your Mac is more than capable of providing you with years of reliable, useful Unix computing.
Also remember that the very openness and raw power offered by these Unix systems affords you with a great opportunity to get familiar with the very basics of what makes your favourite computer platform tick.
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