Linux Distributions Compared
Several vendors are adding value to existing distributions in various ways. For example, Caldera is adding commercial components to Red Hat Commercial Linux to create their Caldera Network Desktop. WorkGroup Solutions used to enhance Slackware as the base for WGS Linux; they have now switched to basing their work on Red Hat Commercial Linux. Trans-Ameritech sells disks with several distributions, including Slackware and Debian; they base their own value-added work on Slackware, trying to make it easier to install.
Value-add distributions are worth serious consideration, but they aren't the subject of this review. As part of deciding which distribution to get, you may want to consider what you can get from value-add vendors as well as from the base distributions in question. Most value-add vendors (as well as distribution vendors) advertise in Linux Journal.
One of the most common sources of confusion in the Linux world today involves binary file formats (See What is a binary file format? sidebar). The Linux community is in a state of transition from the old “a.out” binary file format to the new “ELF” binary file format, which has many features that are completely missing in the a.out format.
ELF is the binary file format used by Unix System V Release 4, but that doesn't mean that a Linux binary in the ELF file format is compatible with SVR4, nor does it mean that SVR4 binaries can run on Linux. The capability for Linux to run some SVR3 and SVR4 binaries is provided by the iBCS2 compatibility package, which most distributions include.
One of ELF's features is extensibility; with ELF, it is possible for developers to add features that weren't thought of when the format was first designed. For instance, one Linux developer has noted that he could add icons to ELF executables without breaking any software. Icons weren't considered when ELF was developed, but the format is extensible enough that they can be easily added.
But perhaps you don't care if you can add an icon to your ELF binary, or even if anyone else can. What does ELF do for you? Fundamentally, it makes life much easier for Linux developers. It also has a few esoteric features which make it practical to support some software under Linux that was previously impractical to support. So it gives you more and better software available for Linux.
Since the whole Linux community is moving to ELF, you don't want to get stuck with a distribution which does not support ELF. A year from now, it will be almost impossible to find a.out binaries for programs you want, and important bug fixes may only be available for ELF.
Because of this, we have only reviewed distributions which at least support ELF binaries. The only distributions that are reviewed here which are not based on the most current ELF libraries are currently being updated, and should be based on standard ELF libraries by the time you read this.
What do we mean by based?
ELF-based means the entire distribution, or at least, almost the entire distribution, consists of ELF binaries. a.out binaries are not provided with the system, or if they are provided, they aren't part of the “core” of the system or are not available in ELF format.
By contrast, “supports ELF” means that, while the distribution is partially or completely built of binaries in the a.out format, the ELF programming libraries are included so that ELF binaries will also run.
Many distributions are available solely on CD-ROM. There are several reasons for this:
So much software is available for Linux that it is impractical to provide it all on floppies.
It is much easier to install software from CD-ROM than to change floppies once a minute.
A cheap supported CD-ROM drive costs approximately the same as the stack of floppies needed to install a complete Linux distribution.
However, some distributions (including Debian, Red Hat, and Slackware) are available via FTP over the Internet in a form designed to fit on floppies, and Linux System Labs still offers a floppy distribution service, from which you can order an entire Linux distribution on floppies, though it is the only company left, to our knowledge, which does this.
Most distributions are freely available over the Internet, although only some are actively distributed in a way that makes it feasible to install them directly from the Internet. You should be aware that while distributors can restrict you from running commercial software components on more than one machine, they cannot restrict you from installing the base Linux software on multiple machines. A Linux distribution which is packaged in a form which cannot be installed without installing proprietary software that is under copyright licensing terms more strict than the GNU General Public License is probably in violation of copyright law. [And should be completely avoided, in my strongly held opinion—ED]
To sum up, you should feel free to install any Linux distribution you buy on as many machines as you like, as long as you respect the licensing terms of any proprietary software that is included with the distribution. Conversely, the vendor needs to make it possible for you to do so without taking unreasonable steps.
If you encounter a vendor who makes it difficult or impossible to install free components without installing proprietary components that have restrictive licenses, first politely bring the issue to their attention—they may not have considered the issue. If the vendor refuses to resolve the issue, return the distribution, ask for your money back, and send a letter to the Editor of Linux Journal.