Introduction to Linux

What is Linux Distribution?

A Linux distribution, often simply distribution or distro, is a member of the Linux family of Unix-like operating systems comprising the Linux kernel, the non-kernel parts of the GNU operating system, and assorted other software.

Because most (if not all) of the kernel and software packages are free and open source, Linux distributions have taken a wide variety of forms -from fully-featured desktop and server operating systems to minimal environments (typically for use in embedded systems, or for booting from a floppy).

Aside from certain custom software (such as installers and configuration tools) a "distro" simply refers to a particular assortment of applications married with a particularly compiled kernel, such that its "out-of-the-box" capabilities meets most of the needs of its particular end-user base.

To provide a Unix-like environment, Linux distributions contain a set of Unix-like utilities and the libraries needed to support them. In full-featured distributions these are generally taken from the GNU operating system. Distributions optimized for size tend to use more compact alternatives like busybox, uclibc or dietlibc.

There are currently over three hundred Linux distribution projects in active development, constantly revising and improving their respective distributions.

One can distinguish between commercially-backed distributions, such as Fedora (Red Hat), SUSE Linux (Novell), Ubuntu (Canonical Ltd.) and Mandriva Linux and community distributions such as Debian and Gentoo. Usually, the procedures for assembling and testing a distribution prior to release are more elaborate the bigger the user base for the distribution is.

What are major differences between them?

Distributions vary on several dimensions, including:

. Package management

All Linux distributions use some method of distributing files, both on distribution CD-ROMs and via the Web as updates. Most distributions use the Red Hat Package Manager (RPM) system, but some use Debian packages, tarballs, or some other package format.

I favor RPM or Debian packages because they're popular (so you can get lots of software in precompiled, easy-to-install form) and because distributions that use these formats maintain databases of installed software on disk, which is very helpful in system maintenance.

. Commercialization

You can obtain most Linux distributions by downloading them from the Internet (check ftp://sunsite.unc.edu/pub/linux/distributions/,or http://delaware.linux.tucows.com/distribution.php for many of them, or check a given distribution's main web site). You can also obtain most distributions on inexpensive CD-ROMs from Linux retailers. Many books on Linux come with Linux distributions.

These are usually a version or two behind the latest, but are otherwise similar to the inexpensive CD-ROMs. Finally, you can purchase most distributions in "official" boxes from the company that produces the distribution, complete with manual, tech support, and possibly some extra commercial software.

Some distributions, such as Red Hat and SUSE, come in multiple levels of boxed sets. I include links to Amazon's listing for the official boxed-set version of each distribution I describe below (when available), but for the most part the downloadable or "unofficial" CD versions work the same as the "official" boxed packages. (Note: I'm an Amazon associate, and so receive a small cut from any purchase you make through a link to Amazon on this web page.)

. Target audience

Some distributions, such as Debian, are aimed at experienced system administrators. They contain little in the way of flashy install routines or GUI system administration tools. Other distributions, such as Lycoris, are aimed at Linux newbies. They include easy-to-use install routines and GUI system administration tools.

. Support --

When you buy a boxed version of a distribution, you typically get some limited installation support, but details differ. You can often purchase support even for "unofficial" CDs, either from the distribution developer or from a third party.

Linux newsgroups are a great form of support for any variety of Linux, but you're more likely to get good support via newsgroups if you use a popular distribution than if you use a rare one. (The distributions I describe on this page are all at least somewhat popular.)