GPL and What You Need to Know - Page 3

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The Kernel, Distros

The Linux kernel itself is not a complete operating system. It needs to be packaged or distributed with a host of other tools and applications in order to constitute a modern operating system. Thus, a full Linux operating system is commonly referred to as a Linux Distribution.

A Linux distribution is essentially a "snapshot" of the Linux kernel and various applications at a certain release that are packaged together in the distribution by its package maintainers. It is entirely possible for users to freely download a Linux kernel and the various applications and package their own distribution, though the complexity of interaction and dependencies, as well as technical support and quality assurance, are among the issues that usually lead most users to make use of a "mainstream" Linux distribution.

Linux Distributors

There are a number of popular Linux distributions. Arguably, the most popular commercial Linux distribution is Red Hat Linux, which was first created in 1994 and made waves with its IPO in 1999 (at the time it was the 8th biggest, first-day gain in Wall Street history). SUSE Linux, which was acquired by Novell in November 2003, is Red Hat's principal rival in the commercial Linux distribution market and benefits from the tremendous resources that Novell is putting behind it Red Hat and Novell/SUSE benefit from sales/channel agreements with IBM and HP that significantly expand their reach and scope.

France-based Mandrake Linux is also considered a mainstream distribution. In the Asian market, TurboLinux has made some inroads, with the emerging story appears to be the homegrown Linux effort known as Asianux, which was officially created in January 2004.

Community-Based Distributions

Not all Linux distributions are "commercial" distributions. In fact, there are many who would argue that the most popular distributions in use today are in fact "community-based" distributions. Here's a sampling:

Debian

This is a popular distribution with a large user base. It is definitively a strong proponent of free software and its Social Contract, which is the basis of the Open Source Definition.

Gentoo Linux

This distribution gained some momentum in 2004, both in terms of statistical growth and its emerging enterprise platform.

Fedora Project

This was created by Red Hat after it terminated its Red Hat Linux line (as opposed to its current mainstay Red Hat Enterprise Linux). This is a Red Hat-sponsored community distribution that serves as proving ground for the next generation of its Enterprise line. It is an extremely popular and trend-setting distribution in its own right, with the adoption of such innovative technologies as SELinux (Security Enhanced Linux) and NX security for the Linux Kernel.

Other Distributions

There are many other distributions but, for the most part, they are based on one of the mainstream distributions.

Desktop Linux

This refers to a Linux operating system environment that has a GUI and is intended for general users on their desktops (just like a regular version of Microsoft Windows). There are two essential technical components that comprise a Linux desktop, an X Windows System implementation and a desktop environment. Until recently XFree86 was the most common X Windows System implementation, but, due to licensing issues, it has been supplanted by X.org.

KDE

This and GNOME are two main desktop environments that are both actively developed. Most mainstream Linux distributions will allow users to use either of them depending on a user's personal preference.

BSD

The FreeBSD Project is one of the earliest open source operating system projects, and is a direct descendent of the original open source BSD work performed at the University of California at Berkeley. There are currently three mainstream open source BSD variants, NetBSD, OpenBSD and FreeBSD.

The GPL and FOSS Licenses

The GNU GPL (General Public License) is one of the most common and popular FOSS licenses. It is the license under which the Linux kernel itself is licensed and is at the heart of the SCO controversy. SCO claimed at one point that the GPL is unconstitutional, but its dispute really started with IBM over a contract. It has now evolved to include claims that select parts of the Linux kernel were pilfered from Unix System V code, to which SCO claims copyright. The case is slated for trial in 2005.

The GPL essentially encourages and enshrines Freedom for the software code. The code is open. If you would like, you can read the text of the GPL itself. Software that is GPL-licensed is free to be distributed and modified, providing a number of crucial stipulations are met: that it remain free (remember "free" as in freedom not necessarily cost) and that the license is always included.

In some respects, the stipulation that code must always remain free makes the GPL a restrictive license as opposed to a BSD-type license, which has no such restriction.

FOSS applications run the gamut of virtually everything that exists in enterprise IT software today. They are either produced as a project by a developer or foundation or are donated/freed/liberated by a corporate entity to the community. The ongoing discussion by SUN Microsystmes over whether to open source Java is part of the latter discussion. Even Microsoft has gotten into the game with its WiX toolset, one of three projects it has donated to the open source community.

One of the most popular open source repositories is SourceForge, which claims the largest number of projects and developers (currently over 800,000 developers).

The Apache Software Foundation (ASF) contains a number of very influential and popular FOSS applications, including its namesake Apache Web Server, which is the dominant Web server on the Internet today. ASF projects are typically licensed under the Apache Software License.

The Mozilla Foundation is known for the Mozilla and Firefox Web browsers, which are cross-platform and, in light of recent security issues with Microsoft's Internet Explorer, are seen as alternatives to the IE browser.