Linux: Difference between revisions

Revision as of 10:57, 12 November 2009

Revision as of 13:15, 12 November 2009

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{{two other uses|operating systems that use the Linux kernel|the kernel itself|Linux kernel|}}

{{infobox OS

| logo =

| screenshot = [[Image:Tux.svg|150px]]

| caption = [[Tux]] the penguin, mascot of Linux <ref name="LinuxOnLine2008"> {{cite web|url = http://www.linux.org/info/logos.html|title = Linux Logos and Mascots|accessdate = 2009-08-11|last = Linux Online|authorlink = |year = 2008}}</ref>

| family = [[Unix-like]]

| source_model = [[Free and open source software]]

| frequently_updated = yes

| kernel_type = [[Monolithic kernel|Monolithic]]

| supported_platforms = [[IA-32]], [[MIPS architecture|MIPS]], [[x86-64]], [[SPARC]], [[DEC Alpha]], [[Itanium]], [[PowerPC]], [[ARM architecture|ARM]], [[m68k]], [[PA-RISC]], [[s390]], [[SuperH]], [[M32R]] and more <!-- please do not include 64 bit extensions of 32 bit ISAs, e.g. sparc64, ppc64, x86-64, etc. -->

| license = Various including [[GNU General Public License]], [[BSD License]], [[Apache License]], and others

<ref>{{cite web | title = Debian GNU/Linux Licenses – Ohloh | url = https://www.ohloh.net/p/debian/analyses/latest | publisher = ohloh.net | accessdate = 2009-03-27 }}</ref>

| working_state = Current

}}

'''Linux''' (commonly {{pron-en|ˈlɪnʌks}}, {{respell|LI|nuks}} in English<ref>{{cite web|url=http://safalra.com/science/linguistics/linux-pronunciation/|title=Pronunciation of ‘Linux’|last=Safalra|date=2007-04-14|work=Safalra’s Website|accessdate=2009-09-15}}</ref><ref name="Foldoc09Jun06"> {{cite web|url = http://foldoc.org/linux|title = Linux|accessdate = 2009-09-15|last = Free On-Line Dictionary of Computing|authorlink = |year = 2006|month = June}}</ref>, also {{pron-en|ˈlɪnʊks}}<ref>Torvalds used {{IPA|/ˈlɪnʊks/}} in English.<br/>{{ cite newsgroup | newsgroups = comp.os.linux | title = Re: How to pronounce "Linux"? | id = [e-mail] | date = 23 April 1992 | accessdate = 2007-01-09 }}<br/> Torvalds has made available an audio sample with his pronunciation in English ({{IPA|/ˈlɪnʊks/}}: {{cite web | url = http://web.archive.org/web/20080113123140/http://www.paul.sladen.org/pronunciation/ | title = How to pronounce Linux? | accessdate = 2006-12-17 }}) and in Swedish ({{IPA|/ˈlɪːnɤks/}}: {{cite web | url = http://www.kernel.org/pub/linux/kernel/SillySounds/ | title = Linus pronouncing Linux in English and Swedish | accessdate = 2007-01-20 }}</ref>) is a generic term referring to [[Unix-like]] computer [[operating system]]s based on the [[Linux kernel]]. Their development is one of the most prominent examples of [[free and open source software]] collaboration; typically all the underlying [[source code]] can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under the terms of the [[GNU GPL license|GNU GPL]].

Linux is predominantly known for its use in [[server (computing)|server]]s, although can be installed on a wide variety of computer [[hardware]], ranging from [[embedded devices]], mobile phones and even some watches<ref name="IBMLinuxWatch"> {{cite web|url = http://www.trl.ibm.com/projects/ngm/wp10_e.htm|title = Linux Watch|accessdate = 2009-09-29|last = [[IBM]]|authorlink = |year = 2001|month = October}}</ref> to [[supercomputers]].<ref>{{cite web | title = Linux rules supercomputers | url = http://www.forbes.com/home/enterprisetech/2005/03/15/cz_dl_0315linux.html | last = Lyons | first = Daniel | accessdate = 2007-02-22 }}</ref> [[Linux distribution]]s, installed on both desktop and laptop computers, have become increasingly commonplace in recent years, partly owing to the popular [[Ubuntu (operating system)|Ubuntu]] distribution<ref name="Economist"> {{cite web|url = http://www.economist.com/science/displaystory.cfm?story_id=10410912|title = Technology in 2008|accessdate = 2008-04-01 (publicly available Dec 2007 – May 2009, rendered members only in May 2009, quoted at [http://web.ncf.ca/fn352/ubuntu.html#Economist National Capital FreeNet]|last = The Economist|authorlink = |year = 2007|month = December}}</ref> and the emergence of [[netbook]]s.<ref name="Economist04Dec08">{{cite news|url = http://www.economist.com/science/tq/displaystory.cfm?story_id=12673233|title = Small is beautiful|accessdate = 2008-12-21|last = [[The Economist]]|authorlink = |year = 2008|month = December}}</ref>

The name "Linux" comes from the Linux kernel, originally written in 1991 by [[Linus Torvalds]]. The rest of the system usually comprises components such as the [[Apache HTTP Server]], the [[X Window System]], the [[GNOME]] and [[KDE]] [[desktop environment]]s, and [[system utility|utilities]] and [[library (computer science)|libraries]] from the [[GNU Project]] (announced in 1983 by [[Richard Stallman]]). Commonly-used applications with desktop Linux systems include the [[Mozilla Firefox]] web-browser and the [[OpenOffice.org]] office application suite. The GNU contribution is the basis for the [[Free Software Foundation]]'s preferred name ''[[GNU/Linux naming controversy|GNU/Linux]]''.<ref name="lsag">{{ cite book | url = http://www.tldp.org/LDP/sag/html/sag.html#GNU-OR-NOT | title = Linux System Administrator's Guide | chapter = 1.1 | edition = version 0.9 | date = 2004 | accessdate = 2007-01-18 | first = Alex | last = Weeks }}</ref><ref name="gnu_homepage">{{cite web|url=http://www.gnu.org/ |title=The GNU Operating System |publisher=Gnu.org |accessdate=2009-04-17}}</ref>

== History ==

{{double image|right|Richard Matthew Stallman cropped.jpeg|150|Linus Torvalds cropped.jpeg|150|[[Richard Stallman]], left, founder of the [[GNU project]], and [[Linus Torvalds]], right, [[author]] of the [[Linux kernel]]}}

{{See also|History of Linux}}

===Unix===

The [[Unix]] operating system was conceived and implemented in 1969 at [[AT&T]]'s Bell Laboratories in the [[United States]] by [[Ken Thompson]], [[Dennis Ritchie]], [[Douglas McIlroy]], and [[Joe Ossanna]] and first released in 1971. Unix was written in [[assembly language]] and later re-written in C in 1973 by [[Dennis Ritchie]]. Its wide availability and [[Porting|portability]] due to being written in [[C (programming language)|C]] meant that it was widely adopted, copied and modified by academic institutions and businesses, with its design being influential on authors of other systems.{{Citation needed|date=August 2009}}

===GNU===

The [[GNU Project]], started in 1983 by [[Richard Stallman]], had the goal of creating a "''complete Unix-compatible software system''" composed entirely of [[free software]]. Work began in 1984.<ref name="gnu_announce">{{cite web|url=http://www.gnu.org/gnu/initial-announcement.html |title=About the GNU Project – Initial Announcement |publisher=Gnu.org |date=2008-06-23 |accessdate=2009-03-09}}</ref> Later, in 1985, Stallman created the [[Free Software Foundation]] and wrote the [[GNU General Public License]] (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries, [[compiler]]s, [[text editor]]s, a [[Unix shell]], and a windowing system) were completed, although low-level elements such as [[device driver]]s, [[daemon (computer software)|daemon]]s, and the [[Kernel (computer science)|kernel]] were stalled and incomplete.<ref name="gnu history">{{cite web|url=http://www.gnu.org/gnu/gnu-history.html |title=Overview of the GNU System |publisher=Gnu.org |date= |accessdate=2009-03-09}}</ref> Linus Torvalds has said that if the GNU kernel had been available at the time (1991), he would not have decided to write his own.<ref>{{cite web | url = http://people.fluidsignal.com/~luferbu/misc/Linus_vs_Tanenbaum.html | title = Linus vs. Tanenbaum debate }}</ref>

=== MINIX ===

[[Image:AndrewTanenbaum.JPG|thumb|right|[[Andrew S. Tanenbaum]], [[author]] of the [[MINIX]] operating system]]

[[MINIX]] was a cheap minimal [[Unix-like]] operating system, designed for education in computer science, written by [[Andrew S. Tanenbaum]] (now Minix is [[free software|free]] and redesigned also for “serious” use).

In 1991 while attending the [[University of Helsinki]], Torvalds began to work on a non-commercial replacement for [[MINIX]],<ref>{{ cite newsgroup | title = What would you like to see most in minix? | newsgroup = comp.os.minix | id = [e-mail] | url = http://groups.google.com/group/comp.os.minix/msg/b813d52cbc5a044b | last = Torvalds | first = Linus | accessdate = 2006-09-09 }}</ref> which would eventually become the [[Linux kernel]].

Torvalds began the development of Linux on Minix and applications written for Minix were also used under Linux. Later Linux matured and it became possible for Linux to be developed under itself.<ref>{{cite news | title = Chicken and egg: How was the first linux gcc binary created?? | newsgroup = comp.os.minix | url = http://groups.google.com/group/comp.os.linux/msg/4ae6db18d3f49b0e }}</ref> Also GNU applications replaced all Minix ones because, with code from the GNU system freely available, it was advantageous if this could be used with the fledgling OS. Code licensed under the GNU GPL can be used in other projects, so long as they also are released under the same or a compatible license. In order to make the Linux kernel compatible with the components from the GNU Project, Torvalds initiated a switch from his original license (which prohibited commercial redistribution) to the GNU GPL.<ref>{{cite web | title = Release notes for Linux v0.12 | first = Linus | last = Torvalds | url = http://www.kernel.org/pub/linux/kernel/Historic/old-versions/RELNOTES-0.12 | authorlink = Linus Torvalds | date = 1992-01-05 | accessdate = 2007-07-23 | publisher = Linux Kernel Archives | quote = The Linux copyright will change: I've had a couple of requests to make it compatible with the GNU copyleft, removing the “you may not distribute it for money” condition. I agree. I propose that the copyright be changed so that it confirms to GNU ─ pending approval of the persons who have helped write code. I assume this is going to be no problem for anybody: If you have grievances ("I wrote that code assuming the copyright would stay the same") mail me. Otherwise The GNU copyleft takes effect as of the first of February. If you do not know the gist of the GNU copyright ─ read it. }}</ref> Developers worked to integrate GNU components with Linux to make a fully functional and free operating system.<ref name="gnu history"/>

=== Commercial and popular uptake ===

{{Main|Linux adoption}}

Today Linux distributions are used in numerous domains, from [[embedded system]]s to [[supercomputer]]s,<ref>{{cite web | title = Linux system development on an embedded device | url = http://www-128.ibm.com/developerworks/library/l-embdev.html | first = Anand | last = Santhanam | coauthors = Vishal Kulkarni | work = DeveloperWorks | publisher = IBM | date = 1 March 2002 | accessdate = 2007-07-26 }}</ref><ref>{{cite web| last = Lyons | first = Daniel| title = Linux rules supercomputers | url = http://www.forbes.com/home/enterprisetech/2005/03/15/cz_dl_0315linux.html | accessdate = 2007-02-22}}</ref> and have secured a place in [[server (computing)|server]] installations with the popular [[LAMP (software bundle)|LAMP]] application stack.<ref>{{cite web| last = Schrecker| first = Michael| title = Turn on Web Interactivity with LAMP | url = http://www.techsoup.org/learningcenter/webbuilding/page5067.cfm | accessdate = 2007-02-22}}</ref> Use of Linux distributions in home and enterprise desktops has been expanding.<ref name="galli2007">{{cite news | first=Peter | last=Galli | coauthors= | title=Vista Aiding Linux Desktop, Strategist Says | date=[[2007-08-08]] | publisher=Ziff Davis Enterprise Inc. | url =http://www.eweek.com/c/a/Linux-and-Open-Source/Vista-Aiding-Linux-Desktop-Strategist-Says/ | work =eWEEK | pages = | accessdate = 2007-11-19 | language = }}</ref><ref name="paul2007">{{cite news | first=Ryan | last=Paul | coauthors= | title=Linux market share set to surpass Win 98, OS X still ahead of Vista | date=[[2007-09-03]] | publisher=Ars Technica, LLC | url =http://arstechnica.com/news.ars/post/20070903-linux-marketshare-set-to-surpass-windows-98.html | work =Ars Technica | pages = | accessdate = 2007-11-19 | language = }}</ref><ref name="beer2007">{{cite news | first=Stan | last=Beer | coauthors= | title=Vista to play second fiddle to XP until 2009: Gartner | date=[[2007-01-23]] | publisher=iTWire | url =http://www.itwire.com.au/content/view/8842/53/ | work =iTWire | pages = | accessdate = 2007-11-19 | language = }}</ref><ref name="applications2007"> {{cite web|url=http://marketshare.hitslink.com/report.aspx?qprid=2&qpmr=15&qpdt=1&qpct=3&qptimeframe=Y |title=Operating System Marketshare for Year 2007 |accessdate=2007-11-19 |date=2007-11-19 |work=Market Share |publisher=Net Applications }}</ref><ref name="xitimonitor2007">{{cite news | first= | last= | coauthors= | title=Vista slowly continues its growth; Linux more aggressive than Mac OS during the summer | date=[[2007-09-24]] | publisher=AT Internet/XiTi.com | url =http://www.xitimonitor.com/en-us/internet-users-equipment/operating-systems-august-2007/index-1-2-7-107.html | work =XiTiMonitor | pages = | accessdate = 2007-11-19 | language = }}</ref><ref name="globalstats2007"> {{cite web|url=http://www.w3counter.com/globalstats.php |title=Global Web Stats |accessdate=2007-11-19 |date=2007-11-10 |work=W3Counter |publisher=Awio Web Services LLC }}</ref><ref name="zeitgeist2004"> {{cite web|url=http://www.google.com/press/zeitgeist/zeitgeist-jun04.html |title=June 2004 Zeitgeist |accessdate=2007-11-19 |date=2004-08-12 |work=Google Press Center |publisher=Google Inc. }}</ref> They have also gained popularity with various local and national governments. The federal government of Brazil is well known for its support for Linux.<ref>{{cite web | url = http://news.cnet.com/Brazils-love-of-Linux/2009-1042_3-6245409.html | title = Brazil's love of Linux | accessdate = 2009-02-21 }}</ref><ref>{{cite news | url = http://news.bbc.co.uk/2/hi/business/3445805.stm | title = Brazil falls in love with Linux | accessdate = 2009-02-21 }}</ref> News of the Russian military creating their own Linux distribution has also surfaced.<ref>{{cite web | url = http://www.osor.eu/news/lv-minister-open-standards-improve-efficiency-and-transparency | title = LV: Minister: "Open standards improve efficiency and transparency" | accessdate = 2009-02-21 }}</ref> Indian state of [[Kerala]] has gone so far as to make it mandatory for all state high schools to run Linux on their computers.<ref>{{cite web | url = http://www.businessweek.com/globalbiz/content/sep2006/gb20060921_463452.htm | title = Linux Spreads its Wings in India | accessdate = 2009-02-21 }}</ref><ref>{{cite web | url = http://www.indianexpress.com/news/kerala-shuts-windows-schools-to-use-only-linux/280323/0 | title = Kerala shuts windows, schools to use only Linux | accessdate = 2009-06-22 }}</ref> [[People's Republic of China|China]] uses Linux exclusively as the operating system for its [[Loongson]] processor family to achieve technology independence.<ref>{{cite web | url = http://www.mdronline.com/watch/watch_Issue.asp?Volname=Issue+%23110308&on=1 | title = China’s Microprocessor Dilemma | accessdate = 2009-04-15 | publisher = [[Microprocessor Report]] }}</ref> In [[Spain]] some regions have developed their own Linux distributions, which are widely used in education and official institutions, like [[gnuLinEx]] in [[Extremadura]] and [[Guadalinex]] in [[Andalusia]]. [[France]] and [[Germany]] have also taken steps towards the adoption of Linux.<ref>{{cite web | url = http://seattlepi.nwsource.com/business/48925_linuxop01.shtml | title = Some countries are choosing Linux systems over Microsoft | accessdate = 2009-02-21 }}</ref>

Linux distributions have also become popular with the newly founded [[netbook]] market, with many devices such as the [[Eee pc|ASUS Eee PC]] and [[Aspire One|Acer Aspire One]] shipping with customized Linux distributions pre-installed.

=== Current development ===

Torvalds continues to direct the development of the kernel. Stallman heads the Free Software Foundation, which in turn supports the GNU components. Finally, individuals and corporations develop third-party non-GNU components. These third-party components comprise a vast body of work and may include both kernel modules and user applications and libraries. Linux vendors and communities combine and distribute the kernel, GNU components, and non-GNU components, with additional package management software in the form of [[Linux distribution]]s.

== Design ==

A Linux-based system is a modular [[Unix-like]] operating system. It derives much of its basic design from principles established in Unix during the 1970s and 1980s. Such a system uses a [[monolithic kernel]], the [[Linux kernel]], which handles process control, networking, and [[peripheral]] and [[file system]] access. [[Device drivers]] are integrated directly with the kernel.

Separate projects that interface with the kernel provide much of the system's higher-level functionality. The GNU [[Userland (computing)|userland]] is an important part of most Linux-based systems, providing the most common implementation of the [[C standard library|C library]], a popular [[shell (computing)|shell]], and many of the common [[Unix tool]]s which carry out many basic operating system tasks. The [[graphical user interface]] (or GUI) used by most Linux systems is based on the [[X Window System]].

=== User interface ===

{{See also|User interface}}

Users can control a Linux-based system through a [[command line interface]] (or CLI), a [[graphical user interface]] (or GUI), or through controls attached to the associated hardware (this is common for embedded systems). For desktop systems, the default mode is usually graphical user interface, where the CLI is available through [[terminal emulator]] windows or on a separate [[virtual console (PC)|virtual console]].

On desktop machines, [[KDE]], [[GNOME]] and [[Xfce]] are the most popular user interfaces,<ref>{{cite web | title = Debian popularity-contest program information | url = http://times.debian.net/1092-30000-popcon-submissions }}</ref> though a variety of additional user interfaces exist. Most popular user interfaces run on top of the [[X Window System]] (often simply called "X"), which provides [[network transparency]], enabling a graphical application running on one machine to be displayed and controlled from another.

Other GUIs include [[X window manager]]s such as [[FVWM]], [[Enlightenment (window manager)|Enlightenment]] and [[Window Maker]]. The window manager provides a means to control the placement and appearance of individual application windows, and interacts with the X Window System. This is a more [[minimalism (computing)|minimalist]] goal than KDE, GNOME et al., which are termed [[desktop environment]]s.

A Linux system typically provides a CLI through a [[Shell (computing)|shell]], which is the traditional way of interacting with a Unix system. A Linux distribution specialized for servers may use the CLI as its only interface. A [[headless system]] that runs without even a monitor can be controlled by the command line via a remote-control protocol such as [[Secure Shell|SSH]] or [[telnet]].

Most low-level Linux components, including the GNU [[Userland (computing)|userland]], use the CLI exclusively. The CLI is particularly suited for automation of repetitive or delayed tasks, and provides very simple [[inter-process communication]]. A graphical [[terminal emulator]] program is often used to access the CLI from a Linux desktop.

== Development ==

[[Image:Unix history.svg|thumb|220px|A summarized history of [[Unix-like]] operating systems showing Linux's origins. Note that despite similar architectural designs and concepts being shared as part of the [[POSIX]] standard, Linux does not share any non-free source code with the original [[Unix]] or [[Minix]].]]

{{Main|Linux distribution}}

The primary difference between Linux and many other popular contemporary operating systems is that the [[Linux kernel]] and other components are [[free software|free]] and [[open source software]]. Linux is not the only such operating system, although it is by far the most widely used. Some [[free software license|free]] and [[open source license|open source]] software licenses are based on the principle of [[copyleft]], a kind of reciprocity: any work derived from a copyleft piece of software must also be copyleft itself. The most common free software license, the [[GNU GPL]], is a form of copyleft, and is used for the Linux kernel and many of the components from the [[GNU project]].

Linux based distributions are intended by developers for [[interoperability]] with other operating systems and established computing standards. Linux systems adhere to [[POSIX]],<ref>{{cite web | url = http://www.ukuug.org/newsletter/linux-newsletter/linux@uk21/posix.shtml | title = POSIX.1 (FIPS 151-2) Certification }}</ref> [[Single UNIX Specification|SUS]],<ref>{{cite web | title = How source code compatible is Debian with other Unix systems? | url = http://www.debian.org/doc/FAQ/ch-compat.en.html#s-otherunices | work = Debian FAQ | publisher = the Debian project }}</ref> [[International Organization for Standardization|ISO]] and [[American National Standards Institute|ANSI]] standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.<ref>{{cite web | url = http://www.linuxjournal.com/article/0131 | title = Certifying Linux }}</ref>

Free software projects, although developed in a [[Collaboration|collaborative]] fashion, are often produced independently of each other. The fact that the software licenses explicitly permit redistribution, however, provides a basis for larger scale projects that collect the software produced by stand-alone projects and make it available all at once in the form of a [[Linux distribution]].

A [[Linux distribution]], commonly called a "distro", is a project that manages a remote collection of system software and application software packages available for download and installation through a network connection. This allows the user to adapt the operating system to his/her specific needs. Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. A distribution can be installed using a CD that contains distribution-specific software for initial system installation and configuration. A package manager such as [[Synaptic Package Manager|Synaptic]] or [[YAST]] allows later package upgrades and installations. A distribution is responsible for the default configuration of the installed Linux kernel, general system security, and more generally integration of the different software packages into a coherent whole.

=== Community ===

{{See also|Free software community|Linux Users Group}}

A distribution is largely driven by its developer and user communities. Some vendors develop and fund their distributions on a volunteer basis, [[Debian]] being a well-known example. Others maintain a community version of their commercial distributions, as [[Red Hat]] does with [[Fedora (Linux distribution)|Fedora]].

In many cities and regions, local associations known as [[Linux Users Group]]s (LUGs) seek to promote their preferred distribution and by extension free software. They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users. Many [[Internet]] communities also provide support to Linux users and developers. Most distributions and free software / open source projects have [[IRC]] chatrooms or [[newsgroup]]s. [[Online forum]]s are another means for support, with notable examples being [[LinuxQuestions.org]] and the [[Gentoo Linux|Gentoo]] forums. Linux distributions host [[mailing list]]s; commonly there will be a specific topic such as usage or development for a given list.

There are several technology websites with a Linux focus. Print [[magazine]]s on Linux often include [[cover disk]]s including software or even complete Linux distributions.<ref>{{cite web | url=http://www.linuxformat.co.uk/dvd/ | title=Linux Format DVD contents | author=[[Linux Format]] | accessdate=2008-01-17 }}</ref><ref>{{cite web | url=http://www.linux-magazine.com/resources/current_issue | title=Current Issue | author=[[Linux Magazine|linux-magazine.com]] | accessdate=2008-01-17 }}</ref>

Although [[Linux distributions]] are generally available without charge, several large corporations sell, support, and contribute to the development of the components of the system and of [[free software]]. These include [[Dell]], [[IBM]], [[Hewlett-Packard|HP]], [[Oracle Corporation|Oracle]], [[Sun Microsystems]], [[Novell]], [[Nokia]]. A number of corporations, notably [[Red Hat]], have built their entire business around Linux distributions.

The [[free software licenses]], on which the various software packages of a distribution built on the Linux kernel are based, explicitly accommodate and encourage commercialization; the relationship between a Linux distribution as a whole and individual vendors may be seen as [[symbiosis|symbiotic]]. One common business model of commercial suppliers is charging for support, especially for business users. A number of companies also offer a specialized business version of their distribution, which adds proprietary support packages and tools to administer higher numbers of installations or to simplify administrative tasks. Another business model is to give away the software in order to sell hardware.

=== Programming on Linux ===

Most Linux distributions support dozens of [[programming language]]s. The most common collection of utilities for building both Linux applications and operating system programs is found within the [[GNU toolchain]], which includes the [[GNU Compiler Collection]] (GCC) and the [[GNU build system]]. Amongst others, GCC provides compilers for [[Ada (programming language)|Ada]], [[C (programming language)|C]], [[C++]], [[Java (programming language)|Java]], and [[Fortran]]. The Linux kernel itself is written to be compiled with GCC. [[Proprietary software|Proprietary]] compilers for Linux include the [[Intel C++ Compiler]], [[Sun Studio (software)|Sun Studio]], and IBM XL C/C++ Compiler. [[BASIC]] is supported in such forms as [[Gambas]], [[FreeBASIC]], and [[XBasic]].

Most distributions also include support for [[PHP]], [[Perl]], [[Ruby programming language|Ruby]], [[Python programming language|Python]] and other [[Dynamic programming language|dynamic languages]]. While not as common, Linux also supports [[C Sharp (programming language)|C#]] via the [[Mono (software)|Mono]] project, sponsored by [[Novell]], and [[Scheme programming language|Scheme]]. A number of [[Java Virtual Machine]]s and development kits run on Linux, including the original Sun Microsystems JVM ([[HotSpot]]), and IBM's J2SE RE, as well as many open-source projects like [[Kaffe]].

The two main frameworks for developing graphical applications are those of [[GNOME]] and [[KDE]]. These projects are based on the [[GTK+]] and [[Qt (toolkit)|Qt]] [[widget toolkit]]s, respectively, which can also be used independently of the larger framework. Both support a wide variety of languages. There are a number of [[Integrated development environment]]s available including [[Anjuta]], [[Code::Blocks]], [[Eclipse (computing)|Eclipse]], [[KDevelop]], [[Lazarus (software)|Lazarus]], [[MonoDevelop]], [[NetBeans]], and [[Omnis Studio]] while the long-established editors [[Vim (text editor)|Vim]] and [[Emacs]] remain popular.<ref>{{cite web | first = Joe | last = Brockmeier | title = A survey of Linux Web development tools | url = http://programming.linux.com/programming/05/10/03/1828224.shtml?tid=63&tid=47 | accessdate = 2006-12-16 }}</ref>

== Uses ==

As well as those designed for general purpose use on desktops and servers, distributions may be specialized for different purposes including: [[computer architecture]] support, [[Embedded Linux|embedded systems]], stability, security, localization to a specific region or language, targeting of specific user groups, support for [[real-time computing|real-time]] applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include only [[free software]]. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.<ref>{{cite web | url = http://lwn.net/Distributions/ | title = The LWN.net Linux Distribution List | accessdate = 2006-05-19 }}</ref>

Linux is a widely [[porting|ported]] operating system kernel. The Linux kernel runs on a highly diverse range of [[computer architecture]]s: in the hand-held [[ARM architecture|ARM]]-based [[iPAQ]] and the [[mainframe computer|mainframe]] [[IBM]] [[System z9]], in devices ranging from [[mobile phone]]s to [[supercomputer]]s.<ref>{{cite web| url = http://www.freeos.com/articles/4737/ | title = If I could re-write Linux | first = Prakash | last = Advani | date = 8 February 2004 | accessdate = 2007-01-23 | publisher = freeos.com }}</ref> Specialized distributions exist for less mainstream architectures. The [[ELKS]] kernel [[fork (software development)|fork]] can run on [[Intel 8086]] or [[Intel 80286]] [[16-bit]] microprocessors, while the [[µClinux]] kernel fork may run on systems without a [[memory management unit]]. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as [[Macintosh]] computers (with both [[PowerPC]] and [[Intel]] processors), [[Personal digital assistant|PDA]]s, [[video game console]]s, [[Digital audio player|portable music players]], and [[mobile phone]]s.

There are several industry associations and hardware [[conference]]s devoted to maintaining and improving support for diverse hardware under Linux, such as [[FreedomHEC]].

=== Desktop ===

[[Image:Gnome-2.20-screenshot.png|thumb|[[GNOME]]]]

[[Image:KDE 4.png|thumb|[[KDE]]]]

[[Image:Xfce-4.4.png|thumb|[[Xfce]]]]

{{Main|Desktop Linux}}

The popularity of Linux on standard desktops (and laptops) has been increasing over the years. Currently most distributions include a graphical user environment. The two most popular such environments, [[GNOME]] and [[KDE]], both of which are mature, support a wide variety of languages.

In the past, the performance of Linux on the desktop has been a controversial topic; for example in 2007 [[Con Kolivas]] accused the Linux community of favoring performance on servers. He quit Linux kernel development because he was frustrated with this lack of focus on the desktop, and then gave a "tell all" interview on the topic.<ref>{{cite web|title=Linux: why I quit|url=http://apcmag.com/node/6735/|accessdate=2008-01-18|date=2007-07-24|work=APC Magazine|publisher=ACP Magazines}}</ref> However since then significant effort has been expended improving the desktop experience. For example, projects such as [[upstart]] aim for a faster boot time.<ref>{{cite web|title=Performance of Java on Ubuntu vs Windows|url=http://www.phoronix.com/scan.php?page=article&item=java_vm_performance&num=1}}</ref> In the field of [[Linux gaming|gaming]], the Linux desktop still lags behind Windows,<ref>{{Cite web|url=http://www.phoronix.com/scan.php?page=article&item=908&num=1 |title=A Synopsis Of Linux Graphics Drivers |author=Michael Larabel |date=9 November 2007 |accessdate=31 March 2009}}</ref> however there are [[Linux_gaming#Commercial_games|several companies]] that do port their own or other companies' games to Linux.

Many types of applications available for [[Microsoft Windows]] and [[Mac OS X]] are also available for Linux. Commonly, either a [[free software]] application will exist which does the functions of an application found on another operating systems, or that application will have a version that works on Linux (such as [[Skype]]). Furthermore, the [[Wine (software)|Wine]] project provides a Windows compatibility layer to run unmodified Windows applications on Linux. [[CrossOver]] is a proprietary solution based on the open source [[Wine (software)|Wine]] project that supports running Windows versions of [[Microsoft Office]], [[Intuit]] applications such as [[Quicken]] and [[QuickBooks]], [[Adobe Photoshop]] versions through CS2, and many popular games such as ''[[World of Warcraft]]'' and ''[[Team Fortress 2]]''. In other cases, although there is no Linux port of some software in areas such as [[desktop publishing]]<ref> {{cite web|url=http://www.freeos.com/articles/2540/ |title=Microsoft Office for Linux? |accessdate=2008-02-03 |last=Advani |first=Prakash |date=2000-10-27 |work=FreeOS |publisher=FreeOS Technologies (I) Pvt. Ltd. }}</ref> and [[professional audio]],<ref> {{cite web|url=http://arstechnica.com/guides/tweaks/linux-audio.ars |title=Editing audio in Linux |accessdate=2008-02-03 |last=Smith-Heisters |first=Ian |date=2005-10-11 |work=Ars Technica |publisher=Ars Technica, LLC }}</ref><ref> {{cite web|url=http://www.keyboardmag.com/article/linux-its-not/apr-07/27458 |title=Linux: It's Not Just For Computer Geeks Anymore |accessdate=2008-02-03 |last=Lumma |first=Carl |date=April 2007 |work=Keyboard Magazine |publisher=New Bay Media, LLC. }}</ref><ref> {{cite web|url=http://www.soundonsound.com/sos/feb04/articles/mirrorimage.htm |title=Using Linux For Recording & Mastering |accessdate=2008-02-03 |last=James |first=Daniel |date=February 2004 |work=Sound On Sound |publisher=SOS Publications Group }}</ref> there is equivalent software available on Linux.

Many popular applications are available for a wide variety of operating systems. For example [[Mozilla Firefox]], and [[OpenOffice.org]] have downloadable versions for all major operating systems. Furthermore, some applications were initially developed for Linux (such as [[Pidgin (software)|Pidgin]], and [[GIMP]]) and, due to their popularity, were ported to other operating systems (including Windows and Mac OS X).

A growing number of proprietary desktop applications are also supported on Linux,<ref>{{cite web | url = http://www.iist.unu.edu/globaldesktop/ | title = The Global Desktop Project, Building Technology and Communities|accessdate = 2006-05-07 }}</ref> see [[List of proprietary software for Linux]]. In the field of animation and visual effects, most high end software, such as [[Maya (software)|AutoDesk Maya]], Softimage XSI and [[Shake (software)|Apple Shake]], is available for Linux, Windows and/or Mac OS X.

The collaborative nature of free software development allows distributed teams to [[L10n|localize]] Linux distributions for use in locales where localizing proprietary systems would not be cost-effective. For example the [[Sinhalese language]] version of the [[Knoppix]] distribution was available significantly before [[Microsoft Windows XP]] was translated to Sinhalese.{{Citation needed|date=April 2009}} In this case the Lanka Linux User Group played a major part in developing the localized system by combining the knowledge of university professors, [[linguist]]s, and local developers.

To install new software in Windows, users either download a digital distribution or use a traditional installation medium (such as CD-ROM). Both of these methods usually provide a "Software Installation Wizard" to guide the user through the setup. On most Linux distributions, there are utilities for browsing a list of thousands of applications installed with a single click. Some of these programs are the [[Synaptic Package Manager]], [[PackageKit]], and [[Yellow dog Updater, Modified|Yum Extender]]. However, installing software not in the official repositories is not always easy, and sometimes the only option is to compile from source.

=== Servers and supercomputers ===

[[Image:Server Linux.jpg|thumb|left|Servers designed for Linux]]

[[Linux distributions]] have long been used as [[Server (computing)|server]] operating systems, and have risen to prominence in that area; [[Netcraft]] reported in September 2006 that eight of the ten most reliable internet hosting companies ran Linux distributions on their [[web server]]s.<ref>{{cite web | title = Rackspace Most Reliable Hoster in September | url = http://news.netcraft.com/archives/2006/10/07/rackspace_most_reliable_hoster_in_september.html | publisher = Netcraft | date = 7 October 2006 | accessdate = 2006-11-01}}</ref> (As of June 2008, Linux distributions represented five of ten, [[FreeBSD]] three of ten, and [[Microsoft]] two of ten.<ref>{{cite web | title = Aplus.Net is the Most Reliable Hosting Company Site in June 2008 | url = http://news.netcraft.com/archives/2008/07/07/aplusnet_is_the_most_reliable_hosting_company_site_in_june_2008.html | publisher = Netcraft | date = 7 July 2008 | accessdate = 2008-07-28}}</ref>)

[[Image:Roadrunner supercomputer HiRes.jpg|thumb|Components of [[IBM Roadrunner]], the world's fastest [[supercomputer]] 2008, which runs Linux.<ref name="top500_osfam" />]]

Linux distributions are the cornerstone of the [[LAMP (software bundle)|LAMP]] server-software combination (Linux, [[Apache HTTP Server|Apache]], [[MySQL]], [[Perl]]/[[PHP]]/[[Python (programming language)|Python]]) which has achieved popularity among developers, and which is one of the more common platforms for website hosting.

[[Linux distribution]]s are also commonly used as [[operating systems]] for [[supercomputer]]s: as of June 2009, out of the [[TOP500|top 500]] systems, 443 (88.6%) run a Linux distribution.<ref name="top500_osfam">{{cite web|author=TOP500.org |url=http://www.top500.org/stats/list/33/osfam |title=Operating system Family share for 06/2009 &#124; TOP500 Supercomputing Sites |publisher=Top500.org |date= |accessdate=2009-07-02}}</ref>

=== Embedded devices ===

{{See also|Embedded Linux|Linux devices}}

[[Image:T-Mobile_G1_launch_event_2.jpg|thumb|An [[HTC Dream]] running [[Android (operating system)|Android]]]]

Due to its low cost and ability to be easily modified, an [[embedded Linux]] is often used in [[embedded systems]]. Linux has become a major competitor to the proprietary [[Symbian OS]] found in the majority of smartphones—16.7% of [[smartphone]]s sold worldwide during 2006 were using Linux<ref>{{cite web | url = http://www.informationweek.com/showArticle.jhtml?articleID=197000995 | title = The Palm OS Clings To Life }}</ref>—and it is an alternative to the proprietary [[Windows CE]] and [[Palm OS]] operating systems on [[mobile device]]s. Cell phones or PDAs running on Linux and built on open source platform became a trend from 2007, like [[Nokia N810]], [[Openmoko]]'s [[Neo1973]], Motorola RAZR2 v8, [[Motorola ROKR E8]], Motorola MING series, Motorola ZINE and the on-going [[Google Android]]. The popular [[TiVo]] digital video recorder uses a customized version of Linux.<ref>{{cite web | url = http://www.tivo.com/linux/linux.asp | title = TiVo ─ GNU/Linux Source Code | accessdate = 2006-12-12 |archiveurl=http://web.archive.org/web/20070519150730/http://www.tivo.com/linux/linux.asp |archivedate=2007-05-19}}</ref> Several network [[firewall]] and [[router]] standalone products, including several from [[Cisco]]/[[Linksys]], use Linux internally, using its advanced firewall and routing capabilities. The [[Korg OASYS]] and the [[Yamaha Motif|Yamaha Motif XS]] [[music workstation]]s also run Linux.<ref>{{cite web |url=http://www.mvista.com/downloads/Case_study_MontaVista_Linux_and_Yamaha.pdf |title=Case Study: How MontaVista Linux helped Yamaha developers make a great product greater |accessdate=2007-08-26}}</ref> Furthermore, Linux is used in the leading [[stage lighting]] control system, FlyingPig/HighEnd WholeHogIII Console.<ref>{{cite web | url=http://www.highend.com/products/controllers/Wholehog3Console.asp | title=Embedded Linux: FlyingPigs the WholeHogIII runs on Linux}}</ref>

=== Market share and uptake ===

{{Main|Linux adoption}}

Many quantitative studies of [[Free software|free]] / open source software focus on topics including market share and reliability, with numerous studies specifically examining Linux.<ref>{{cite web | first = David A | last = Wheeler | url = http://www.dwheeler.com/oss_fs_why.html | title = Why Open Source Software/Free Software (OSS/FS)? Look at the Numbers! | accessdate = 2006-04-01 }}</ref> The Linux market is growing rapidly, and the revenue of servers, desktops, and packaged software running Linux was expected to exceed $35.7 billion by 2008.<ref>{{cite web | url = http://www.techweb.com/wire/showArticle.jhtml?articleID=55800522 | title = Linux To Ring Up $35 Billion By 2008 | accessdate = 2006-04-01 }}</ref>

[[International Data Corporation|IDC]]'s Q1 2007 report indicated that Linux held 12.7% of the overall server market at that time.<ref name="Linux-watch.com IDC's Q1 2007 report">{{cite web|url=http://www.linux-watch.com/news/NS5369154346.html |title=─ IDC Q1 2007 report |publisher=Linux-watch.com |date=2007-05-29 |accessdate=2009-03-09}}</ref> This estimate was based on the number of Linux servers sold by various companies and did not include server hardware purchased separately and had Linux installed on it later. In September 2008 Microsoft CEO [[Steve Ballmer]] admitted that 60% of servers run Linux versus 40% that run [[Windows Server]].<ref name="PC World September 2008">

{{cite web|url = http://www.pcworld.com/businesscenter/article/151568/ballmer_still_searching_for_an_answer_to_google.html|title = Ballmer Still Searching for an Answer to Google|accessdate = 2009-06-04|last = Niccolai|first = James|authorlink = |year = 2008|month = September}}</ref>

Estimates for the desktop market share of Linux range from less than one percent to 10–12 percent. In comparison, [[List of Microsoft operating systems|Microsoft operating systems]] hold more than 85%.<ref name="galli2007"/><ref name="paul2007"/><ref name="beer2007"/><ref name="applications2007"/><ref name="xitimonitor2007"/><ref name="globalstats2007"/><ref name="zeitgeist2004"/><ref name="Byfield04May09"> {{cite web|url = http://itmanagement.earthweb.com/osrc/article.php/12068_3818696_2/Linux-Desktop-Market-Share-Greater-Than-One-Percent.htm|title = Linux Desktop Market Share: Greater Than One Percent?|accessdate = 2009-05-06|last = Byfield|first = Bruce|authorlink = |year = 2009|month = May}}</ref><ref name="Schroder28May09"> {{cite web|url = http://blog.linuxtoday.com/blog/2009/05/1-linux-microso.html|title = Tiny 1% Linux = Big Microsoft Terror|accessdate = 2009-05-30|last = Schroder|first = Carla|authorlink = |year = 2009|month = May}}</ref><ref name="W3CCounterJuly09"> {{cite web|url = http://www.w3counter.com/globalstats.php|title = W3Counter – Global Webstats|accessdate = 2009-08-22|last = Awio Web Services|authorlink = |year = 2009|month = August}}</ref>

The frictional cost of switching operating systems and lack of support for certain hardware and application programs designed for [[Microsoft Windows]] have been two factors that have inhibited adoption. Proponents and analysts attribute the relative success of Linux to its security, reliability,<ref>{{cite web | url = http://www-306.ibm.com/software/info/features/feb152005/ | title = Why customers are flocking to Linux }}</ref> low cost, and freedom from [[vendor lock-in]].<ref>{{cite web | url = http://www.ca.com/za/news/2005/20051010_linux.htm| title = The rise and rise of Linux }}</ref>

Also most recently Google has begun to fund [[Wine (software)|Wine]], which acts as a compatibility layer, allowing users to run some Windows programs under Linux.<ref>{{cite mailing list |last=Kegel |first=Dan |url=http://article.gmane.org/gmane.comp.emulators.wine.devel/56872 |title=Google's support for Wine in 2007 |date=2008-02-14 |mailinglist=wine-devel |accessdate=2009-01-03}}</ref><ref>{{cite web

|url=http://code.google.com/opensource/wine.html

|title=Open Source Patches: Wine

|publisher=Google

|accessdate=2008-09-07

}}</ref>

The [[OLPC XO-1|XO laptop]] project of One Laptop Per Child is creating a new and potentially much larger Linux community, planned to reach millions of schoolchildren and their families and communities in developing countries.<ref>{{cite web|title=mission|url=http://www.laptop.org/en/vision/mission/index.shtml|publisher=laptop.org|accessdate=2008-08-14}}</ref> [[Google]], [[Red Hat]], and [[eBay]] are major supporters of the project.<ref>[http://www-static.laptop.org/vision/progress/ One Laptop per Child (OLPC), a low-cost, connected laptop for the world's children's education]</ref> While the XO will also have a Windows option, it will be primarily deployed using [[Sugar (desktop environment)|Sugar]], a desktop environment for [[Fedora (operating system)|Fedora]] Linux.

In the film industry, Linux has been the platform of choice for several years. The first major film produced on Linux servers was [[Titanic (1997 film)|Titanic]] in 1997. Since then major studios like [[Dreamworks Animation]], [[Pixar]] and [[Industrial Light & Magic]] have moved to Linux.<ref>{{cite web | url = http://www.linuxjournal.com/article/5472 | title = Industry of Change: Linux Storms Hollywood | accessdate = 2009-03-11 }}</ref><ref>{{cite web | url = http://video.fosdem.org/2008/maintracks/FOSDEM2008-tuxwithshades.ogg | title = Tux with Shades, Linux in Hollywood | accessdate = 2009-03-11 }}</ref> Currently more than 95% of the servers and desktops at large animation and visual effects companies use Linux.<ref>{{cite web | url = http://www.linuxmovies.org/ | title = LinuxMovies.org – Advancing Linux Motion Picture Technology | accessdate = 2009-03-11 }}</ref>

{{See also|Usage share of desktop operating systems|List of Linux computers}}

== Copyright and naming ==

The Linux kernel and most GNU software are [[software license|license]]d under the [[GNU General Public License]] (GPL). The GPL requires that anyone who distributes the Linux kernel must make the source code (and any modifications) available to the recipient under the same terms. In 1997, Linus Torvalds stated, “Making Linux GPL'd was definitely the best thing I ever did.”<ref>{{cite web | url = http://kde.sw.com.sg/food/linus.html | title = Linus Torvalds interview | accessdate = 2007-09-13 |archiveurl=http://web.archive.org/web/20070311190841/http://kde.sw.com.sg/food/linus.html |archivedate=2007-03-11}}</ref> Other key components of a Linux system may use other licenses; many libraries use the [[GNU Lesser General Public License]] (LGPL), a more permissive variant of the GPL, and the [[X Window System]] uses the [[MIT License]].

Torvalds states that the Linux kernel will not move from version 2 of the GPL to version 3. He specifically dislikes some provisions in the new license which prohibit the use of the software in [[digital rights management]],<ref>{{cite web | url=http://lkml.org/lkml/2006/1/25/273 | title=Re: GPL V3 and Linux ─ Dead Copyright Holders | author=Torvalds, Linus | date=2006-01-26 | publisher=[[Linux Kernel Mailing List]]}}</ref><ref>{{cite web | url=http://lkml.org/lkml/2006/9/25/161 | title=Re: GPLv3 Position Statement | author=Torvalds, Linus | date=2006-09-25 | publisher=[[Linux Kernel Mailing List]]}}</ref> and it would also be impractical to obtain permission from all the copyright holders, who number in the thousands.<ref>[http://www.linux-watch.com/news/NS3301105877.html Linux-Watch.com – Keeping an Eye on the Penguin]</ref>

A 2001 study of [[Red Hat Linux]] 7.1 found that this distribution contained 30 million [[source lines of code]]. Using the [[COCOMO|Constructive Cost Model]], the study estimated that this distribution required about eight thousand man-years of development time. According to the study, if all this software had been developed by conventional [[proprietary software|proprietary]] means, it would have cost about ${{formatprice|{{inflation|US|1080000000|2000}}|0}} ({{CURRENTISOYEAR}} US dollars) to develop in the United States.<ref name = "estimating_size">{{cite web | first = David A | last = Wheeler | date = 2002-07-29 | url = http://www.dwheeler.com/sloc/redhat71-v1/redhat71sloc.html | title = More Than a Gigabuck: Estimating GNU/Linux's Size | accessdate = 2006-05-11 }}</ref>

Most of the code (71%) was written in the [[C (programming language)|C]] [[computer programming|programming]] [[programming language|language]], but many other languages were used, including [[C++]], [[assembly language]], [[Perl]], [[Python (programming language)|Python]], [[Fortran]], and various [[shell script]]ing languages. Slightly over half of all lines of code were licensed under the GPL. The Linux kernel itself was 2.4 million lines of code, or 8% of the total.<ref name = "estimating_size"/>

In a later study, the same analysis was performed for [[Debian|Debian GNU/Linux]] version 4.0.<ref>{{cite web | first = Juan José | last = Amor | coauthors = et al. | date = 17 June 2007 | url = https://penta.debconf.org/~joerg/attachments/33-measuring_etch_slides.pdf | title = Measuring Etch: the size of Debian 4.0 | accessdate = 2007-09-16 }}</ref> This distribution contained over 283 million source lines of code, and the study estimated that it would have cost ${{formatprice|{{inflation|US|7170186240|2007}}|0}} ({{CURRENTISOYEAR}} US dollars) to develop by conventional means. <!-- original paper quoted 5358000000 euros, but Wikipedia does not have an inflation calculator for euros; converted to USD via June 17 2007 exchange rate as provided by http://www.bankofcanada.ca/en/rates/exchform.html and double-checked against other sources of historical exchange rates ... it is also more useful to quote the number in dollars, for comparison to other dollar amounts quoted in this article, e.g. the 2001 study above -->

In the United States, the name ''Linux'' is a trademark registered to Linus Torvalds.<ref>{{cite web | url = http://assignments.uspto.gov/assignments/q?db=tm&rno=1916230 | title = U.S. Reg No: 1916230 | publisher = United States Patent and Trademark Office | accessdate = 2006-04-01 }}</ref> Initially, nobody registered it, but on 15 August 1994, William R. Della Croce, Jr. filed for the trademark ''Linux'', and then demanded royalties from Linux distributors. In 1996, Torvalds and some affected organizations sued him to have the trademark assigned to Torvalds, and in 1997 the case was settled.<ref>{{cite web | url = http://www.linuxjournal.com/article/9065 | title = Linux Timeline | publisher = Linux Journal | date = 31 May 2006 }}</ref> The licensing of the trademark has since been handled by the [[Linux Mark Institute]]. Torvalds has stated that he trademarked the name only to prevent someone else from using it. LMI originally charged a nominal sublicensing fee for use of the Linux name as part of trademarks,<ref>{{cite news

| author = Neil McAllister

| title = Linus gets tough on Linux trademark

| url = http://www.infoworld.com/article/05/09/05/36OPopenent_1.html

| work = [[InfoWorld]]

| date = 2005-09-05

| accessdate = 2008-02-24

}}</ref> but later changed this in favor of offering a free, perpetual worldwide sublicense.<ref>{{cite web

| url = http://www.linuxmark.org

| title = Linux Mark Institute

| accessdate = 2008-02-24

| quote = LMI has restructured its sublicensing program. Our new sublicense agreement is: Free — approved sublicense holders pay no fees; Perpetual — sublicense terminates only in breach of the agreement or when your organization ceases to use its mark; Worldwide — one sublicense covers your use of the mark anywhere in the world

}}</ref>

{{See also|SCO-Linux controversies}}

=== GNU/Linux ===

{{Main|GNU/Linux naming controversy}}

The [[Free Software Foundation]] views Linux distributions which use GNU software as [[GNU variants]] and they ask that such operating systems be referred to as ''GNU/Linux'' or ''a Linux-based GNU system''.<ref name="Stallman01">{{cite web | title = Linux and the GNU Project | url = http://www.gnu.org/gnu/linux-and-gnu.html | first = Richard | last = Stallman | authorlink = Richard Stallman | date = 2007-03-03 | accessdate = 2007-03-12 | publisher = Free Software Foundation }}</ref> The media and common usage, however, refers to this family of operating systems simply as ''Linux'', as do many large Linux distributions (e.g. [[Ubuntu (operating system)|Ubuntu]]<ref name="UbuntuHomePage"> {{cite web|url = http://www.ubuntu.com/|title = About Ubuntu|accessdate = 2009-03-22|last = [[Canonical Ltd.]]|authorlink = |year = 2009}}</ref> and [[SuSE]] Linux). Some distributions use ''GNU/Linux'' (particularly notable is [[Debian|Debian GNU/Linux]], on which Ubuntu is based), but the term's use outside of the enthusiast community is limited. The naming issue remains controversial. Linus Torvalds does not support the use of the term GNU/Linux.<ref>{{cite video|people=Moore, J.T.S. (Produced, Written, and Directed)|title=[[Revolution OS]]|medium=DVD|year=2001}}</ref>

== See also ==

{{wikiversity2|Operating_Systems/GNU-Linux|Linux}}

{{Portal|Linux|NewTux.svg}}

{{fossportal}}

* [[Comparison of Linux distributions]]

* [[Comparison of Windows and Linux]]

* [[Comparison of open source and closed source]]

* [[evdev]]

* [[Free as in Freedom: Richard Stallman's Crusade for Free Software]]

* [[Linux Documentation Project]]

* [[Linux Standard Base]]

* [[List of Linux distributions]]

* [[List of Linux kernel names]]

* [[Plan 9 from Bell Labs]]

* [[The Cathedral and the Bazaar]]

== References ==

{{refs|3}}

==Further reading==

*{{cite book|last=Weinberg|first=Bill|title=Uniting Mobile Linux Application Platforms|publisher=LinuxPundit.com|date=July 2008|pages=18|url=http://www.linuxpundit.com/cv/docs/Platforms_WP_LP.pdf}}

== External links ==

{{sisterlinks}}

*[http://www.linux.org/ Linux.org website]

*[http://www.linux.com/ Linux.com website]

*[http://www.kernel.org/ Linux kernel website and archives]

*[http://www.linuxmark.org/ The Linux Mark Institute] (manages the Linux trade mark)

*[http://www.linux-foundation.org/ The Linux Foundation]

*[http://www.gnu.org/ GNU Project website]

*[http://www.tldp.org/ The Linux Documentation Project]

*{{HSW|2830-episode-55-intro-to-linux-video|Intro to Linux}}

*[http://www.makelinux.net/reference Catalog of Linux, GNU and FOSS documentation]

*[http://www.linfo.org/ The Linux Information Project (LINFO)]

*[http://www.makelinux.net/system/ Graphical map of Linux, GNU and FOSS]

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