Linux distribution: Meaning (information, definition, explanation, facts)

A Linux distribution or GNU/Linux distribution (or a distro) is a Unix-like operating system plus application software comprising the Linux kernel, the GNU operating system, assorted free software and sometimes proprietary software, all created by individuals, groups or 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, more or less ready to install and use. There are over 200 different Linux distributions in active development.

History

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 configuration and placement of files in the system.

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, the user interface or convenient packaging.

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 University about the same time, and
• SLS (SoftLanding Linux System).

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 Slackware, the oldest distribution still in active development.

Linux distributions attracted users as an alternative to the Microsoft Windows operating systems on the PC and to MacOS on the Apple Macintosh. Most early adopters were used to UNIX from work or school. They embraced Linux for its stability, low cost and for the inclusion of the source code for most or all of the software included.

The distributions were originally simply 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.

The Linux kernel, GNU, and most of the additional software making up a typical Linux distribution are free and open source software, distributed by its maintainers both as pre-compiled binaries and in source code form, allowing users to compile the original source code into binary or executable form if they wish.

A Linux distribution almost always offers compiled versions of the Linux kernel, GNU 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 (e.g, 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 many other distributors as well
• deb — Debian package, originally from Debian but also used by others
• 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
• ebuild — the file containing information on how to retrieve, compile, and install a package in Gentoo's Portage system using the command emerge. Typically these are source-primary installs, though binary packages can be installed in this fashion as well.
• src — building the packages from source (often binary packages are provided in parallel on many systems).

Although Linux distributions typically contain much more software than proprietary operating systems, it is normal for local administrators to install software not included with the distribution. An example would be a newer version of <some software application> 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 distributors differ from most operating system vendors in not claiming that "no administration is required." This honesty can worry 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.

These are the most popular and therefore the most common distributions of Linux for PCs and other workstations, listed approximately alphabetically.

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.

• Adamantix: Debian-based distribution focusing on security.
• Arch Linux: A sourced base distribution focused for the advanced user.
• Amber Linux: A Debian-based distribution tailored specifically to the needs of Latvian users.
• Ark Linux: A GNU/Linux distribution focusing on ease of use and ease of learning, while remaining technically sane.
• ASPLinux: RedHat-compatible distribution, with out-of-the-box support for Russian and other Cyrillic-based languages.
• Beehive
• Cobind Desktop
• Conectiva: A Brazilian distribution. Founding member of United Linux.
• Debian GNU/Linux: 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 has a reputation for being more difficult to install than others, and for being somewhat politically motivated.
• Damn Small Linux - A live distro designed for mini-cds
• Fedora Core - A General purpose distro for workstation, desktop and server use. Developed by Red Hat and the community.
• 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, though this has improved in recent years. Gentoo is basically an automated Linux From Scratch.
• GoboLinux: An alternative Linux distribution which redefines the entire filesystem hierarchy.
• Hiweed GNU/Linux([1]): A easy-to-use distribution based on Debian GNU/Linux.
• Icepack Linux: A user-friendly, full-featured operating system, pre-configured, well structured and easy to work with.
• Impi Linux: A Debian-based distribution from South Africa that focuses on the needs of African users.
• Knoppix: A Live CD version of Debian which is instantly usable after booting from the CD and comes with 2GB of software on the single CD. The Gnobian version is Gnoppix.
• Kurumin: A Brazilian Knoppix-based distribution.
• 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.
• LinEx: Gnobian official distribution of Extremadura (Spain)
• Linspire: Another desktop-oriented distribution, previously called Lindows, which is based on licensed Xandros code and Debian. Additional software is available from Linspire or via Debian's apt command, although compatibility with Debian is not guaranteed. Has significant proprietary content.
• Linux From Scratch: Not really a distro. Linux from Scratch is a document describing how to assemble your own Linux-based operating system. It is intended as a learning experience. Some people prefer Linux from Scratch for the flexibility it offers. Gentoo has since appeared, which offers the same level of flexibility, but automates much of the drudge work.
• Linux Mobile System: A Fedora Core/Red Hat Linux-based system supporting the new USB keydrives.
• LinuxXP: An easy-to-use distribution without the hassle of re-partitioning the hard drive and going through complicated processes of hardware configuration.
• 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.
• Magic Linux([2]): A easy-to-use distribution specified to Chinese users.
• Mandrakelinux: Mandrakelinux is among the easiest distributions 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 non-members of their club.
• 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.
• MkLinux: A distribution for PowerPC systems which runs the Linux kernel as a server on top of the Mach microkernel.
• Morphix: A LiveCD Debian distribution with different flavours, including GNOME.
• Onebase Linux: has been built from scratch to support both binary and source based installation of packages seamlessly using OLM (Onebase Linux Management). Targeted towards both novices and developers.
• PCLinuxOS: A easy-to-use LiveCD distribution. Originally based on Mandrake 9.2, it has since pursued its own course of development, focusing on desktop users.
• Red Flag Linux: A distribution based in China and optimised for the Chinese market.
• Red Hat Linux, now split into Red Hat Enterprise Linux and Fedora Core: 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: The oldest distribution still actively maintained. Console-oriented package management. Known for its focus on security and stability.
• Sorcerer GNU/Linux: An advanced, source based distribution.
• Source Mage: Source-based distribution that started as a GPL fork of the Sorcerer GNU/Linux project.
• SPBLinux: Mini-distribution for floppies and USB keydrives.
• Sun Wah RAYS LX: A Debian-based desktop distribution, developed in China.
• SuSE: Based in Nürnberg, Germany, SUSE is one of the most popular distributions 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.
• ThizLinux: ([3]) A HongKong based distribution provide services to Great China. Member of China.
• Turbolinux: A popular distribution in Asia. Member of United Linux.
• United Linux: A group of 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 proprietary software. Xandros is based on Debian and is designed to be compatible with Debian's dpkg package management system.
• Yggdrasil - An old Linux distribution.
• Yellow Dog: A Red Hat-based distribution for the PowerPC platform, maintained by Terra Soft Solutions.
• YOPER: "Your Operating System", a desktop distribution from New Zealand.

Some groups compile special purpose Linux distributions as turnkey firewalls, for embedded systems, and for other special purposes.

• Linux in special devices:
  • Linux in Floppies: see Linux floppydistros.
  • Bootable business card distros.
  • In hard disks: Linux On a Disk
  • Embedded Debian
• Demudi: A distribution for multimedia work.
• Trinux: Security tools distribution.
• SmoothWall: A router/firewall distribution.
• Sentry Firewall
• The Linux Router Project
• Tinfoil Hat Linux: A distribution for the security-conscious/paranoid.
• Flightlinux: A distribution for spacecraft.
• Gibraltar (Linux distribution): Router and firewall distribution bootable from CD-ROM.
• SELinux: Security-enhanced version of the Linux kernel created by the US National Security Agency.
• coLinux: Cooperative Linux is a free and open source method for running Linux on Microsoft Windows natively. [4]
• EduLinux: based on Mandrake Linux, it was developed at the University of Sherbrooke for educational purposes. http://www.edulinux.org

The Linux Standard Base is an organization devoted to allowing co-operation 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.