Q YouÆve spent time telling us about Linux, but what about us Mac users? Is there a version of Linux for the superior hardware ù Apple, that is? And if so, is it something I can just switch on when I need it, or is it a major shift?

A Yes, there are versions of Linux for the Mac. MkLinux and LinuxPPC are two popular implementations. However, they both need to take over your entire Mac when they're running. This means that you have to restart your computer whenever you want to switch between Linux and the Mac OS. You'll also have to dedicate at least 500MB of hard disk space to a Linux installation. Fortunately, however, MkLinux and LinuxPPC are similar enough that despite the differences between the two, both can run the same apps.

MkLinux

First introduced in 1995, MkLinux is the oldest Linux for the Mac, and its development was originally funded by Apple. It's completely free ù you can download it from ftp://ftp.mklinux.apple.com. For those who don't want to spend time downloading its multihundred-megabyte bulk, you can purchase the software on CD from specialist vendors such as EverythingLinux (www.everythinglinux.com.au, (02) 9798 7604).

MkLinux's main advantage is hardware compatibility: it runs on just about every Power Mac out there, including the original 6100, 7100, and 8100 series. Since those are the PowerPC-based Macs that are most likely to be declared too old to use, they're also the most likely candidates for conversion into Linux-based systems. The result: Macs once slated for the giveaway pile can provide solid performance in their new lives.

LinuxPPC

The other Mac-based Linux is LinuxPPC (www.linuxppc.com). Unlike MkLinux, whose evolution has floundered, LinuxPPC is under very active development, bringing continuous improvements in usability, speed, and reliability with it. LinuxPPC can also be downloaded for free, but it's much more convenient to purchase the package in CD format.

LinuxPPC is leaner and meaner than MkLinux. Its developers have taken advantage of the more open systems that Apple designed and built in the days of Mac clones. The LinuxPPC team has created a Linux that is even more streamlined ù and therefore faster ù than MkLinux.

Unfortunately, LinuxPPC runs only on Power Macs that have a PCI bus. The good news is that it does work on all PowerPC-based systems other than the 6100/7100/8100 family; its Performa siblings; or the PowerBook 1400, 2400, and 5300 models. (The definitive list of supported hardware is at linuxppc.org/hardware.) It's a pity that the first Power Mac generation is left out, but unless Apple provides the LinuxPPC team with the necessary documentation, MkLinux will remain the only option for those Macs.

Perhaps the most important thing about LinuxPPC is its attention to making Linux as painless to install as possible. The latest version of LinuxPPC, release 5.0, will include a brand-new graphical installer that will help you set up Linux on your Power Mac fairly easily. You can even set Linux to boot directly into an X Windows graphical user interface rather than a scary command-line interface, if you so desire.

However, all these improvements to the process don't mean that running LinuxPPC is as easy as running a Mac. Linux is still something for people with a "techy" mentality. And much more than is the case with computers running the Mac OS, Unix-based systems are vulnerable to attack if you're not careful. Unix will often load a number of server applications invisibly and by default. If you're planning on running a Linux server that's accessible to the whole Internet, you must learn a bit more about Unix system administration than if you are just setting up a local workgroup server.

Apps

And while there are only a few general-use Linux applications out there, the numbers are growing. You can run Netscape Communicator on LinuxPPC, and Applix (www.applix.com) will soon offer a version of its Applixware suite of business apps for LinuxPPC. One by one, the barriers to getting started with Unix are disappearing. Hopefully, by the release of Mac OS X they will have faded away completely.

- Stephan Somogyi