Summary
In this first column aimed at those new to Linux, Rick Cook tackles the questions: What exactly is a Linux distribution? Is it the same as a version? Are all distributions created equal? Will software written for one distribution run on all others? (1,300 words) By Rick Cook

Distributions offer many new Linux users their first glimpse at what makes Linux different. In the Linux world the cake is free -- and standard. It's the icing that's not standard, and it doesn't have to be free either.

At the heart of Linux is the kernel and filesystem -- the basic, fundamental parts of Linux. This core is distributed under a license, under terms that require it to be provided in its entirety, with source code, to anyone who wants it. With it, you also normally get an extensive suite of software tools and utilities written by the Free Software Foundation's GNU project, which began developing its own version of Unix way back in 1984. The GNU software suite includes several shells (or command-line interfaces), a C/C++ compiler, the X Windows windowing system to provide a mouse-and-icon interface, and so on.

On top of this -- the icing, if you will -- is the software, added by each distributor (the Calderas and Red Hats of the world). This is the stuff that distinguishes one distribution from another. In the case of commercial vendors, this is where the distributor tries to add enough value to make you purchase its version of Linux.

Distributions aren't versions in the sense the rest of the computing world understands the term. The kernel and filesystem are the same, and a lot of the surrounding material, such as the X Window System, is the same. You see the difference in the installation program, which processor is supported, and added material. Price varies as well, from free for download, to just a few bucks for a CD-ROM and book, to over $200, depending on what's included and the intended market.

There are between one and two dozen English-language Linux distributions available, and a number of non-English distributions. (See "Linux Online" in the Resources section.) The distribution suppliers range from highly professional companies looking to make big bucks in the Linux industry to hobbyists releasing their own distribution just for fun.

Different distributions exist for different machines. Power Mac, Alpha, and UltraSPARC boxes are all supported by a number of different distributions, and some differences exist between Intel distributions. For example, some versions are designed to run on any Intel processor from 386 up, while others are tuned and optimized for the Pentium. A couple of distributions are even designed to fit on a single floppy disk.

While the different varieties of Linux available are distributions rather than versions, each new release of the Linux kernel is called a new version. In general, you want to get the most recent version of the kernel possible, but this usually doesn't have anything to do with the distributor you choose. What's more, your distribution's version number generally bears no relationship to the kernel version number. For example, Caldera OpenLinux 1.3 features the Linux kernel version 2.0.35. Got it?

The important thing to remember is that if your distribution has a 2.something kernel, you're probably fine.

You don't have to buy a distribution, of course. Let's not forget that Linux is free; you can download the kernel, filesystem and other parts at no charge. However, if you chose to do it yourself, you're pretty much stuck with the job of making sure you have all the parts you want and installing them properly on your computer.

Three reasons to buy something that's free

If do you purchase a distribution, you're really buying three things: ease of installation, a limited degree of support, and additional software.

Painless installation is important, and a lot of Linux vendors have gone out of their way to make sure their customers get it. They include scripts, installation programs, and other features to get you up and running as painlessly as possible. They also try support as much hardware as they can. Red Hat Linux has a reputation for being especially strong in the area of installation, as does Slackware.

In general, Linux is easy to install using these installation features. I got my first distribution (Slackware 3.5) up and running in about 20 minutes, thanks to the installation program. However, the installation routines do hide a lot of the complexity inherent in a multitasking, multiuser operating system. Sometimes things don't work the way they should, especially if you deviate from the well-trodden path and choose to do a custom installation. That's where support comes in.

Between vendors, you'll see considerable difference in the level of installation support. Some, like Caldera and Red Hat, offer support for a limited period to help users get Linux installed. Others take the attitude that you're on your own. If you're experienced with Unix or Linux (or can get to the appropriate Internet newsgroups to ask questions) you can probably overcome any roadblocks you run into. For the rest of us, that support-desk telephone number is very comforting.

The included software makes good marketing copy, but it's less important than ease of installation and support. With Linux, almost all the software is available for download somewhere. If there's a tool or utility you want, you can probably find it for the cost of a download.

Interoperability

Will software written for one distribution of Linux run on another? The answer is generally "Yes, but.." As long as both distributions were written for the same processor, you can probably get the software to work. There are, however, a couple of caveats. One is that due to differences in various utilities, file structures and such, you may have to do some tweaking. For example, you may have to edit the installation script to allow for different filenames or directory names in different distributions. In some cases, you may have to recompile the application, which is a pain if you've never done it before.

Linux distributions are probably going to get easier to use in the near future. Whether this is a good thing or not depends on how you view Linux.

What we're probably going to see is the emergence of one or two de facto standard versions of Linux, with many distributors falling by the wayside. This will make things better for Linux users, especially beginning users, but it will cost the Linux community some of its vitality and make Linux a less exciting, innovative platform. Linux is unlikely to settle into something like Windows, but it probably will change as it matures.

About the author

Rick Cook has been covering computers and high technology for nearly 20 years for various publications. He is the author of a series of fantasy novels full of bad computer jokes.  

Resources More ReadingThe Linux HOWTO Index

http://sunsite.unc.edu./LDP/HOWTO/HOWTO-INDEX.htmlLinux installation and getting started

http://sunsite.unc.edu/LDP/LDP/gs/Linux Online -- a good place to read more

http://www.linux.orgThe Linux Software Map -- a searchable database of many linux packages.

http://www.boutell.com/lsm/Distributions

Sources for information on some of the available distributions of Linux. Most of these companies sell their distribution on CD-ROM and a few of them provide FTP sites for downloading their distribution.Caldera

http://www.caldera.com/Debian

http://www.debian.orgRed Hat

http://www.redhat.comLinux Mandrake. A French company with the Mandrake distribution (in English)

http://www.linux-mandrake.com/Linux PPC. A distribution of Linux for the PowerPC processor

http://www.linuxppc.org/Linux Pro Plus

http://www.LinuxMall.com/Allprod/lxcdr.htmlTrans-Am

http://www.trans-am.com/MkLinux: Linux for the Power Mac

http://www.mklinux.apple.com/ Walnut Creek CD ROM Handles the Slackware Linux distribution

http://www.cdrom.com/Stampede

http://www.stampede.org/S.u.S.E. Inc. A popular European distribution (with an English version)

http://www.suse.com/index_us.htmlPacific HiTech Handles the TurboLinux distribution

http://www.pht.com/Yggdrasil Computing Inc. Yggdrasil distribution of Linux.

http://www.yggdrasil.com/

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URL: http://www.linuxworld.com/linuxworld/lw-1998-10/lw-10-linux101.html