Meta-distribution
A Linux distribution or, alternatively, a GNU/Linux distribution (sometimes also called a distro) is a complete Linux operating system: a Linux kernel, a collection of free software releases (usually parts of the GNU system) and sometimes non-free software created by individuals, groups and organizations from around the world.
Companies such as Red Hat, SuSE and MandrakeSoft, as well as community projects such as Debian and Gentoo Linux, assemble and test the software and provide it as a complete system, generally more or less ready to install and use. There are over 100 different Linux distributions in active development.
History
Linux distributions began to appear soon after the Linux kernel was first used by individuals outside the original Linux programmers. They were more interested in developing the operating system than in application programs, or the user interface, or convenient packaging. Before the first distributions, a would-be Linux user was required to be something of a UNIX expert, not only knowing what libraries and executables were needed to successfully get Linux to boot and run, but also important details concerning the files in the system; configuration, placement, ... It was not a time for the faint of heart!
Early distributions included:
- MCC Interim Linux, which was made available to the public for download on the ftp server of University of Manchester in February, 1992;
- TAMU, created by individuals at Texas A & M about the same time, and
- SLS (Software Landing Systems).
None of these distributions were well maintained, and when the owner of the SLS distribution refused to accept some of his fixes, Patrick Volkerding created the Slackware Linux distribution, the oldest distribution still in active development.
Linux distributions attracted users as an alternative to the Microsoft Windows operating systems on the IBM PC and its clones and to the MacOS on the Apple Macintosh machines, mostly from among people used to Unix from work or school. They embraced Linux for its low cost, and for the inclusion of the source code for most (all in some distributions) of the software included.
The distributions were originally simply useful as a convenience, but today they have become the usual resort even for Unix or Linux gurus. To date Linux has proven more popular in the server market, primarily for Web and database servers (see also LAMP), than in the desktop market.
Composition
The Linux kernel and much of the additional software making up a typical Linux distribution is free software; even more of it falls under the somewhat broader definition of open source software. Like all Open Source software (and some Free software), it is distributed by its maintainers in source code form. This allows users to convert the original source code into binary or executable form if they wish (termed compiling). Pre-compiled binaries are also often supplied in distributions.
A Linux distribution almost always offers compiled versions of the Linux kernel, standard system libraries, and assorted programs that make up the rest of an operating system. Many provide an install program / procedure akin to that provided with other operating systems which are distributed in binary form (e.g., Solaris Operating Environment, Microsoft Windows, etc.). Other self-hosting distributions (e.g., Gentoo Linux, etc.) provide the source code of all software but only binaries of a basic kernel, compiler tools (eg, a compiler, make utility and so on), and an installer; the installer compiles all the software specifically for the microarchitecture of the user's machine.
Distributions are normally segmented into packages, each holding a specific application or service; one package may hold a library for handling PNG images, another may contain a number of fonts, while a third one supplies a web browser.
In addition to providing packaged compiled code, most distributions offer tools for installation/removal of packages that are more powerful than simple archiving software. This software is said to be the package management system of the distribution. Each package intended for such a PMS contains meta-information like description, version, "dependencies", etc. The package management system can evaluate this meta-information, to allow package searches, automatic upgrade to newer versions, checking that all dependencies of a package are fulfilled and/or fulfilling them automatically, and more. Package management systems include:
- RPM — now RPM Package Manager, but originally Red Hat Package Manager, originally from Red Hat but now used by most other distributors as well
- deb — Debian package, originally from Debian but also used by others
- and tgz or tar.gz — standard tar + gzip, possibly with some extra control files — used by Slackware and others, or sometimes when distributing very simple handmade packages
Although Linux distributions typically contain much more software than commercial operating systems, it is normal for local administrators to install software not included with the distribution. An example would be a newer version of than that supplied with a distribution, or an alternative to that chosen by the distribution (e.g., KDE rather than GNOME or vice versa). If the additional software is distributed in source-only form, this approach requires local compilation. However, if additional software is locally added, the 'state' of the local system may fall out of synchronization with the state of the package manager's database. If so, the local administrator user will be required to take additional measures to ensure the entire system is kept up to date, that all required patches are installed, etc. The package manager may no longer be able to do so automatically.
Most distributions install packages, including the kernel and other core operating system components, in a predetermined configuration. Few now require or even permit configuration adjustments at first install time. This is less daunting, particularly for new users, but not always acceptable. Since much software must be carefully configured to be useful, to work correctly with other software or to be secure, local administrators will often be obliged to spend time reviewing and reconfiguring assorted software. Some distributions go to considerable lengths to specifically adjust all (or some) of the software they include to their particular distribution (location of particular files and so on), but not all do so. Some distributions provide configuration tools to assist in this process, but, again, not all. Note that such adjustments may be required for a particular site and that it is not, in principle, possible for anyone including a distribution's designer to preconfigure the software provided to meet individual requirements. As with all operating systems, Linux and its distributions impose a system administration obligation on its users/operators/owners. Linux, and most of its distributors, differ from the usual operating system vendors in not claiming that "no administration is required." Honesty is a virtue, but worries potential users who have been told otherwise in marketing.
By replacing everything provided in a distribution, an administrator may reach a 'distribution-less' state: everything was retrieved, compiled, configured, and installed locally. It is possible to build such a system from scratch, bypassing any distribution altogether, but one needs a way to generate the first binaries until the system is self-hosting (i.e., has a bootable kernel, and compilation tools to generate more binaries). This can be done via compilation on another system capable of building binaries for the intended target (possibly by cross-compilation). See Linux From Scratch Guide for instructions.
General-purpose distributions
These are the most popular and therefore the most common distributions of Linux for PCs and other workstations, listed approximately alphabetically; a list by userbase share would have Beehive far lower, and Redhat far higher, among others.:
See: DistroWatch for a comprehensive, up-to-date listing.
They can use different file base distributions (e.g., dpkg for Debian, RPM for Fedora), desktop environment (e.g., KDE, GNOME, XFce), media (e.g., 1 or 2 floppys, LiveCD, bootable Keydrive, only hard disk installation), localization (setting for a language and country), Free software direction or not, for a specific purpose (e.g., firewalls and security, robotics, desktop workstation) and so on.
- ASPLinux: RedHat-compatible version of GNU/Linux (with the out-of-box support of Russian and other Cyrillic-based languages).
- Beehive
- Conectiva: a Brazilian distribution. Founding member of United Linux.
- Debian: Put together by countless volunteers, Debian has the largest selection of packages (over 8000) of any distribution. It supports the largest number of hardware platforms, and is well known for ease of upgrading. It is reputably more difficult to install than others.
- Gentoo: mainly for hobbyists, developers and network professionals. All software that you specify arrives as source code. This unique approach has a twofold intention: to assist (but not to guarantee!) use on almost any platform, and to allow compilers of this source code to optimize for platform specific performance. Installation instructions are available and complete, but a fair amount of hand-tweaking is required, especially if building from source.
- GoboLinux: an alternative Linux distribution which redefines the entire filesystem hierarchy.
- Icepack Linux is a user-friendly, full-featured operating system, pre-configured, well structured and easy to work with.
- Impi Linux: a Debian based Linux from South Africa that focuses on the needs of African users.
- Knoppix: A "LiveCD Debian Linux" distribution which is instantly usable after booting from the CD and comes with 2GB of software in the single CD. The Gnobian version is Gnoppix.
- Libranet: A desktop distribution based upon and 100 % compatible with Debian. The installation has hardware detection and the desktop has an 'adminmenu' (in both text and gui mode) to ease hardware and software configuration.
- Lindows: Another desktop-oriented distribution, which is based on licensed Xandros code and Debian. Additional software is available from Lindows or via Debian's apt command. Has significant proprietary content.
- LinEx : Gnobian official distribution of Extremadura (Spain)
- Linux from Scratch: A source code-based distribution, similar, but pre-dating Gentoo.
- Linux Mobile System: a Fedora/Red Hat Linux full Linux system whose support is the new USB keydrives.
- LinuxXP: provide people who never tried linux before with an easy-to-use linux distribution without the hassle of re-partioning their HD and going through complicated processes of configuring their H/W.
- Lunar Linux: source based distribution that originally forked from the Sorcerer GNU/Linux project.
- Lycoris Desktop/LX: targeted for the desktop market, comparable to Mandrake for ease of installation and use.
- Mandrake: Mandrake tries to be the easiest distribution for beginners. Originally a Red Hat variant optimized for the Pentium CPU, it has since diverged while retaining strong compatibility. While entirely free software, it attempts to raise money by a delayed release strategy for nondonors.
- MEPIS: An easy-to-use Debian-based distribution which also runs as a LiveCD, allowing you to try out MEPIS before you decide to install it on your hard drive.
- Morphix a LiveCD Debian distribution with different flavours, including GNOME.
- Red Flag Linux: Linux targetted for China.
- Red Hat Linux, nowadays Fedora Linux: The most popular distribution in the USA by a large margin, Red Hat has also served as a base for many other distributions. One of the easiest for beginners.
- Slackware: One of, if not the oldest distribution still actively maintained. Difficult to install, with highly limited package management capabilities. Known for its focus on secutity and stability.
- Sorcerer GNU/Linux: an advanced, source based Linux distribution.
- Source Mage: source based distribution that started as a GPL fork of the Sorcerer GNU/Linux project.
- SPBLinux: linux mini distribution for floppys and USB keydrives.
- SuSE: Based in Germany, SuSE is the most popular distribution in Europe. Like Red Hat, it is a large distribution (on 7+ CDs and, recently, 2 DVDs as well. It features a unique configuration tool named YaST. Founding member of United Linux. Recently purchased by Novell.
- Trustix: a somewhat hardened distribution focused on security. Contrast SELinux, from NSA, which is a set of kernel modifications, not a distribution, and cannot be used alone, however.
- Turbolinux: Linux distribution popular in Asia. Member of United Linux.
- United Linux: A group of Linux distributors who banded together to build a common base distribution, based on SuSE. United Linux has now ceased.
- Vector Linux: a lightweight Slackware based distribution. Designed to provide the user with a simplified installer and small, fast applications that function well on older computers as well as new ones.
- Xandros: A newcomer in the distribution market, Xandros (based on the defunct Corel Linux) focuses on the desktop market. The Xandros distribution, unlike most others, may not be freely copied, as it contains commercial software. Xandros is based on Debian and is designed to be compatible with Debian's dpkg package management system.
- YOPER: "Your Operating System", a desktop Linux from New Zealand
Special-purpose distributions
Some groups compile special purpose Linux distributions as turnkey firewalls, for embedded systems, and for other special purposes.
Interdistribution issues
The Linux Standard Base is an organization devoted to allowing cooperation between different distributions. The Filesystem Hierarchy Standard is also an important tool that significantly eases interdistribution cooperation.
Alien is a program that converts between different Linux package distribution file formats. If you want to use a package from another distribution than the one you have installed on your system, you can use alien to convert it to your preferred package format and install it.
See also
External links
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