Linux

Linux (IPA:/ˈlɪnəks/ or/ˈlɪnʊks/) is aUnix-like computeroperating system family based on theLinux Kernel.

Overview[]

Linux is one of the most prominent examples offree software and ofopen source development; its underlyingsource code is available for anyone to use, modify, and redistribute freely.^[1]

The first Linux systems were completed in 1992 by combiningsystem utilities andlibraries from theGNU project with the Linux kernel, which led to the coining of the termGNU/Linux.^[2] From the late 1990s onward Linux gained the support of corporations such asIBM,^[3]Sun Microsystems,^[4]Hewlett-Packard,^[5] andNovell.^[6]

Predominantly known for its use inservers, Linux is used as an operating system for a wider variety of computerhardware than any other operating system, includingdesktop computers,supercomputers,^[7]mainframes, andembedded devices such ascellphones. Linux is packaged for different uses inLinux distributions, which contain the kernel along with a variety of other software packages tailored to requirements.

History[]

In 1983Richard Stallman started theGNU Project with the goal of creating a UNIX-like,POSIX-compatible operating system composed entirely offree software. Development began in 1984, and a year later he created theFree Software Foundation and wrote the first draft of theGNU General Public License (GPLv1). By the early 1990s, the project had produced or collected many necessary operating system components, including libraries,compilers,text editors, and aUnix shell, and the mid-level portions of the OS were almost complete. The upper level could be supplied by theX Window System, but the lower level which consisted of akernel, device drivers, and daemons was still incomplete. In 1990 the GNU project began developing theHurd kernel which was based on theMach microkernel, but development proved difficult and proceeded slowly.^[8]

In 1991,Linus Torvalds began to work on theLinux kernel while he was attending theUniversity of Helsinki.^[9] Torvalds originally created the Linux kernel as a non-commercial replacement for theMinix kernel;^[10] he later changed his original license to theGPLv2, which differed primarily in that it also allowed for commercial redistribution.^[11] Although dependent on the Minixuserspace at first, work from both Linux kernel developers and the GNU project allowed Linux to work with GNU components. Thus Linux filled the last major gap in running a complete, fully functional free operating system.^[8]

In 2004, Ken Brown of theAlexis de Tocqueville Institution cast doubt on Linus' authorship of Linux, which was rebutted^[12] by Minix's author,Andrew S. Tanenbaum.

Development milestones[]

This foundation formed the basis for an operating system which has since been completed by the efforts of numerous members of the free and open source software community. Significant milestones include:

• The launch of theKDEdesktop environment byMatthias Ettrich in October1996 followed by the comparableGNOME alternative byMiguel de Icaza in August1997, both based on theX11 windowing system developed atMIT. GNOME and KDE were the tip of the Linux operating system iceberg that was now in direct contact with end users.
• The release of theNetscapebrowser'ssource code onMarch 31,1998, which kicked off theMozilla project that would eventually give birth to the popularMozilla Firefox browser.

• The release ofStarOffice bySun Microsystems which in June 2000 became the base for the free softwareOpenOffice.org office suite^[13], a major event in the open source office world.See also:list of free software.
• The growth of commercial interest in Linux is similarly marked by notable events: the launch in February1998 of theOpen Source Initiative; the announcement in July1998 byOracle Corporation that it would port its well-knowndatabase software to Linux and provide support for it; theIPOs ofRed Hat onNovember 11,1999 andVA Linux the following month which would create aspeculative bubble; the wide-scale support of technology giantIBM that would spend millions of dollars on Linux, employing in2005 close to 300 developers of theLinux kernel, and would organize starting in2003 the legal defense for theSCO vs. Linux controversy against the attacks of theSCO Group that claimed copyright over theLinux kernel; and finally the acquisition in October and November 2003 ofXimian and thenSuSE by the American technology giantNovell.^[14]

Present day[]

Today Linux is used in numerous domains, fromembedded systems^[15] tosupercomputers,^[16] and has secured a place inserver installations with the popularLAMP application stack.^[17] Torvalds continues to direct the development of the kernel. Stallman heads the Free Software Foundation, which in turn develops 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 combine and distribute the kernel, GNU components, and non-GNU components, with additional package management software in the form ofLinux distributions.

Adoption[]

Main article:Linux adoption

Many quantitative studies of open source software focus on topics including market share and reliability, with numerous studies specifically examining Linux.^[18] The Linux market is growing rapidly, and the revenue of servers, desktops, and packaged software running Linux is expected to exceed $35.7 billion by 2008.^[19] The actual installed user base may be higher than indicated by this figure, as most Linux distributions and applications are freely available and redistributable.

Desktop adoption is weaker than server adoption, with diverse calculations generally figuring between 0.3% and 3% as a function of the sample set and calculation methods used.Template:Fact According to market research companyIDC, 25% of servers and 2.8% of desktop computers ran Linux as of 2004.^[20] The estimate of these numbers is driven by website traffic analysis, which may be complicated by two factors.First, manyweb browsers can modify their identity, either by default or via user action, by exploiting theuser agent string, so as not to be blocked bywebsites that refuse to interact with browsers other thanInternet Explorer running underMicrosoft Windows. Second, a Linux system may be configured not to communicate this information for privacy and security reasons.

Linux Online alleges that people regard Linux as suitable mostly for computer experts because mainstreamcomputer magazine reporters cannot explain what Linux is in a meaningful way, as they lack real life experience using it.^[21] Furthermore, the frictional cost of switching operating systems and lack of support for certain hardware and application programs designed forMicrosoft Windows have been two factors that have inhibited adoption. However, as of early 2007, significant progress in hardware compatibility has been made, and it is becoming increasingly common for hardware to work "out of the box" with many Linux distributions. Proponents and analysts attribute the relative success of Linux to its security, reliability,^[22] low cost, and freedom fromvendor lock-in.^[23]

Naming[]

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In 1992, Torvalds explained how he pronounces the wordLinux:

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Torvalds has made available an audio sample which indicates his own pronunciation, in English (/ˈlɪnʊks/)^[24] and Swedish (/ˈlɪːnɤks/).^[25] English speakers may also pronounce the name as[ˈlaɪnʌks],^[26]/ˈlɪnʊks/, or/ˈlɪnəks/.^[27]

TheFree Software Foundation views Linux distributions which use GNU software as "variants" of the GNU system, and they ask that such operating systems be referred to asGNU/Linux ora Linux-based GNU system.^[28] However, the media and population at large refers to this family of operating systems as Linux. While some distributors make a point of using the aggregate form, most notablyDebian with theDebian GNU/Linux distribution, its use outside of the enthusiast community is limited. The distinction between the Linux kernel and distributions based on it plus the GNU system is a source of confusion to many newcomers, and the naming remains controversial.

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Copyright and Trademark[]

The Linux kernel and most GNU software arelicensed under theGNU General Public License (GPL), version 2. The GPL requires that all distributed source code modifications and derived works also be licensed under the GPL, and is sometimes referred to as a "share and share-alike" or "copyleft" license. In 1997, Linus Torvalds stated, "Making Linux GPL'd was definitely the best thing I ever did."^[29] Other software may use other licenses; many libraries use theGNU Lesser General Public License (LGPL), a more permissive variant of the GPL, and theX Window System uses theMIT License. After more than ten years, the Free Software Foundation announced that they would be upgrading the GPL to version 3, citing increasing concerns withsoftware patents anddigital rights management (DRM).^[30] In particular, DRM is appearing in systems running copyleft software, a phenomenon dubbed "tivoization" afterdigital video recorder makerTivo's use of DRM in their Linux-based appliances.^[31] Linus Torvalds has publicly stated on theLinux Kernel Mailing List that, based on the drafts of the licence, he would not move the Linux kernel to GPL v.3, specifically citing the DRM provisions.^[32][33]

Source code analysis[]

A 2001 study ofRed Hat Linux 7.1 found that this distribution contained 30 millionsource lines of code. Using theConstructive 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 conventionalproprietary means, it would have cost about 1.08 billion dollars (year 2000 U.S. dollars) to develop in the United States.^[34]

Most of the code (71%) was written in theCprogramminglanguage, but many other languages were used, includingC++,Lisp,assembly language,Perl,Fortran,Python and variousshell scripting 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.^[34]

In a later study, the same analysis was performed for Debian GNU/Linux version 2.2.^[35] This distribution contained over fifty-five million source lines of code, and the study estimated that it would have cost 1.9 billion dollars (year 2000 U.S. dollars) to develop by conventional means.

In March 2003, theSCO Group filed alawsuit against IBM, claiming that IBM had contributed parts of SCO's copyrighted code to the Linux kernel, violating IBM's license to use Unix. Also, SCO sent letters to several companies warning that their use of Linux without a license from SCO may be actionable, and claimed in the press that they would be suing individual Linux users. Per theUtahDistrict Court ruling onJuly 3,2006; 182 out of 294 items of evidence provided by SCO againstIBM in discovery were dismissed.^[36]

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Trademark[]

In the United States, the nameLinux is atrademark registered to Linus Torvalds.^[37] Initially, nobody registered it, but onAugust 151994,William R. Della Croce, Jr. filed for the trademarkLinux, and then demanded royalties from Linux distributors. In 1996, Torvalds and some affected organizations sued to have the trademark assigned to Torvalds, and in 1997 the case was settled.^[38] The licensing of the trademark has since been handled by theLinux Mark Institute. Torvalds has stated that he only trademarked the name to prevent someone else from using it, but was bound in 2005 byUnited States trademark law to take active measures to enforce the trademark. As a result, the LMI sent out a number of letters to distribution vendors requesting that a fee be paid for the use of the name, and a number of companies have complied.^[39]

Philosophy[]

The primary difference between Linux and other contemporary operating systems is that the Linux kernel and other components areopen source software. Linux is not the only such operating system, although it is the most well-known and widely used one. Some open source licenses are based on the principle ofcopyleft, a kind of reciprocity: any work derived from a copyleft piece of software must also be copyleft itself. The most common free software license is used for theLinux kernel itself: theGNU GPL written byRichard Stallman.

One of the advantages of open source, as proposed byEric Raymond inThe Cathedral and the Bazaar, is that it allows for rapidsoftware bug detection and elimination, which is important for correctingsecurity exploits. This argument rejects the notion ofsecurity through obscurity.

Interoperability[]

Linux aims for interoperability with other operating systems, and by extension the software that runs on Linux aims for interoperability with other Linux and non-Linux software. As an operating systemunderdog competing with mainstream operating systems, Linux cannot rely on amonopoly advantage; in order for Linux to be a convenient operating system for users that is commercially viable, it must interact well with non-Linux computers. Interoperability also provides users free choice of software and data formats whilst not restricting them as a result of that choice.

Linux systems adhere toPOSIX,SUS,ISO, andANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.^[40][41][42]

A priority is placed onopen formats, public specifications for data that are freely available and free to implement, such that there can be multiple competing independent implementations to choose from, instead of only a single piece of software which can work with a specific format. These contrast withclosed formats, which are either poorly documented or not documented at all, and for which there exists no agreement between competing vendors. When standards exist for network communication protocols, data formats, andAPIs, they contribute to the robustness and adoption of Linux. In some cases, free software projects are the reference implementation of these protocols, examples being theApache HTTP Server,Template:Fact and theX.org implementation of theX Window System.

Examples of standard conformance includeMozilla Firefox which adheres strictly toWorld Wide Web Consortium recommendations,Jabber which formed the basis for theXMPP standard recognized by theInternet Engineering Task Force in the domain ofinstant messaging, and office productivity suites such asOpenOffice.org andKOffice which brought to light the recentOpenDocument standard.

In other domains, there are neither recognized standards nor organizations to manage them. The market is therefore split between software which attempts to interoperate as much as possible, and that which establishes market dominance throughvendor lock-in, or the use ofclosed formats andcommunication protocols. Prime examples of the first category draw from theinstant messaging war, which is ruled by multiprotocol software such asGaim,Kopete, andTrillian. The second category of software is exemplified byMicrosoft Office and its widely used closed file formats, and theCommon Internet File System protocol which allow for files and printers to be shared between different computers on aWindows network.

In these cases, interoperability depends onreverse engineering, which requires a substantial investment on the part of developers. The legal status of reverse engineering varies from country to country; it may be illegal in the United StatesTemplate:Fact but legal in Europe, provided the goal is limited to interoperability.Template:Fact Today, as a result of reverse engineering,OpenOffice.org can read most.doc files, andSamba allows non-Windows machines to interact with a Windows network.

A further problem beyond reverse engineering is when interoperability is needed for a format or protocol that is technically encumbered bydigital rights management orTrusted Computing, or legally restricted bysoftware patents or laws such as theEuropean Copyright Directive andDigital Millennium Copyright Act.

Portability[]

Linux is aportable operating system. While the Linux kernel was originally designed only forIntel 80386microprocessors, it now runs on a more diverse range ofcomputer architectures than any other operating system—^[43] from the hand-heldARM-basediPAQ to themainframeIBMSystem z9, in devices ranging fromsupercomputers tomobile phones. Specialized distributions exist for less mainstream architectures. TheELKS kernelfork can run onIntel 8086 orIntel 8028616-bit microprocessors, while theµClinux kernel may run on systems without amemory management unit including theApple iPod. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as theiMac andPowerBook,Palm PDAs,GameCube,Xbox and even thePlaystation Portable.

Community[]

Linux 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, asRedHat does withFedora Core.

In many cities and regions, local associations known asLinux Users Groups (LUGs) seek to promote Linux and by extension free software. They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users. There are also manyinternet communities that seek to provide support to Linux users and developers. Most distributions and open source projects have a chatroom on the popularfreenodeIRC network that are open to anybody with anIRC client.Online forums are another means for support, with notable examples beingLinuxQuestions.org and theGentoo forums. Finally, every established free software project and Linux distribution has one or moremailing lists; commonly there will be a specific topic such as usage or development for a given list. TheLinux Kernel Mailing List is a high-volume list where all Linux kernel development happens.SourceForge,Savannah, andApache host many free and open source software projects using standardcollaborative software.

Linux-basednewsgroups are available via theGoogle Groups interface and also vianews readers. There are also several technology websites with a Linux focus.Linux Weekly News is a weekly digest of Linux-related news; theLinux Journal is an online magazine of Linux articles published monthly;Slashdot is a technology-related news website with many stories on Linux and open source software;Groklaw has written in depth about Linux-related legal proceedings; and there are many articles relevant to Linux on theFree Software Foundation website.

People who contribute to free software are not allsoftware developers, as exemplified by theGNOME andKDE projects; there are many non-development contributions needed, as is the case for any software product. Furthermore, the principles of free software and open source have had repercussions in other domains where collaboration is possible and the cost of making copies is marginal. Amongst the members of thisopen source culture are theCreative Commons movement initiated byLawrence Lessig and the collaborative encyclopediaWikipedia founded byJimmy Wales.

Although Linux is generally available free of charge, several large corporations have established business models that involve selling, supporting, and contributing to Linux and free software. These includeIBM,HP,Sun Microsystems,Novell, andRed Hat. The free software licenses on which Linux is based explicitly accommodate and encourage commercialization; the relationship between Linux as a whole and individual vendors may be seen assymbiotic.The business model of commercial suppliers is generally dependent on 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.

Distributions[]

Main article:Linux distribution

Free software projects, although developed in a collaborative fashion, are often produced independently of each other. However, given that the software licenses explicitly permit redistribution, this 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 aLinux distribution.

ALinux distribution, commonly called a "distro", is a project that manages a remote collection of Linux-based software, and facilitates installation of a Linux operating system. Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. They include system software andapplication software in the form ofpackages, and distribution-specific software for initial system installation and configuration as well as later package upgrades and installs. A distribution is responsible for the default configuration of installed Linux systems, system security, and more generally integration of the different software packages into a coherent whole.

A typical general purpose distribution includes the following:

1. Aboot loader: A menu system that will allow the user to select which operating system to load in the process ofbooting a computer system. The most common bootloaders areLILO orGRUB.
2. Linux kernel: The core or heart of the operating system. The name of the OS comes from here.
3. GNU Compiler Collection: A set of tools that allow a programmer to write and compile program code and shell scripts.
4. GNU C Library
5. GNU bash shell,X Window System networking and display protocol and an accompanyingdesktop environment such asKDE,GNOME,orXfce together with thousands of application software packages, fromoffice suites towebservers tomedia players to3D computer graphics software totext editors, and scientific programs.

As well as those designed for general purpose use, distributions may be specialized for different purposes including:computer architecture support,embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support forreal-time applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include onlyfree software. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.^[44]

Interface[]

Command line interface[]

Linux includes acommand line interface (CLI) as part of itsUnix-like functionality. Distributions specialized for servers or administration may use the CLI as their only interface, for the absence of agraphical user interface (GUI) helps to increase security and minimize system resource consumption. As well, Linux machines can run without a monitor attached. In order for a user to access them, either remoteX11 usage is necessary, or the CLI must be used via a protocol such asSSH ortelnet. On local networks, remoteX11 usage is generally acceptable, but over long distances high network latency can make it impractical.

In the early history of Linux, many operations required CLI usage. The advent of distributions dedicated to desktop and family have changed this. However, online manuals for Linux often mention a CLI-based solution to a problem, even if a GUI-based alternative exists. The CLI is universal in the Linux world, whereas GUIs can differ from machine to machine. It also facilitates inter-operation between Linux and non-Linux machines which also have a CLI;Mac OS X machines are one example. It is also easier for an expert to help a user via the CLI if the user need only copy and paste the advice into a terminal.

Many important programs do not have a GUI, including most of the GNUuserland. This comes from theUnix philosophy of designing a program to do one thing, and to do it well. The CLI is particularly suited for automation of repetitive or delayed tasks, and there is a natural progression where the command to perform a task is first issued directly, and then later reused in a script to provide automation.

Graphical and command line interfaces can also complement each other. There are a host of graphicalterminal emulator programs, includingxterm,rxvt,aterm,gnome-terminal, andkonsole. For these programs, the X11 copy and paste mechanism can facilitate communication between the terminal and GUI applications.

X window managers[]

The traditional GUI for a Linux operating system is based on a stand-aloneX window manager such asFVWM,Enlightenment, orWindow Maker, and a suite of diverse applications running under it. The window manager provides a means to control the placement and appearance of individual application windows, and interacts with theX window system. A high degree of flexibility allows for extensive customization, and the resource requirements in terms of CPU, memory, and hard-disk space consumption are lower than those of a full-fledged desktop environment.Template:Fact

This model contrasts with that of platforms such asMac OS, which were developed during the same era as the X window system. Under such platforms, the user interface is unified by a single toolkit that provides widgets for everything from buttons to window decorations such as title bars, manages window placement, and otherwise provides a consistentlook and feel to the user. Because the X window managers only manage the placement of windows, their decoration, and someinter-process communication, the look and feel of individual applications may vary widely, especially if they use different graphical user interface toolkits.

Desktop environments[]

Main article:X Window System desktop environment

The use of window managers by themselves declined with the rise of Linuxdesktop environments. They combine a window manager with a suite of standard applications that adhere tohuman interface guidelines. Whereas a window manager is analogous to theAqua user interface for OS X, a Linux desktop environment is analogous to Aqua as well as all of the default OS X graphical applications and configuration utilities. Initially,CDE was available as a proprietary solution, but was never popular on Linux systems due to cost and licensing restrictions.Template:Fact In 1996 theKDE was announced, followed in 1997 by the announcement ofGNOME.Xfce is a smaller project that was also founded in 1997, and focuses on speed and modularity. Acomparison of X Window System desktop environments demonstrates the differences between environments.

Applications[]

Desktop[]

Under Linux, desktop software of high quality is in high demand; this includes applications such as word processors, spreadsheets, email clients, and web browsers. The following are the major Linux desktop applications:

• Office:StarOffice/OpenOffice.org. It may be useful tocompare office suites.
• Internet:Firefox,Thunderbird,Evolution,Gaim, andAzureus
• Multimedia:VLC,MPlayer,Xine,XMMS,Totem, andAmarok
• Graphics:The GIMP,Inkscape, andScribus

Although in specialized application domains such asdesktop publishing andprofessional audio there may be a lack of commercial quality software, users migrating from Mac OS X and Windows can find equivalent applications for most tasks.^[45]Furthermore, it is uncommon for a free software project that works under Windows or Mac OS X not to have a Linux version; a user accustomed to using free software under Windows can generally expect to find the same applications running under Linux. A growing amount of proprietary desktop software is also supported under Linux,^[46] examples beingAdobe Flash Player,Acrobat Reader,Nero Burning ROM,Opera,RealPlayer, andSkype. Additionally,Crossover Office is a commercial solution based on the open sourceWINE project that supports running Windows versions ofMicrosoft Office andPhotoshop.

Games[]

Main article:Linux gaming

There are far fewer games available for Linux than for Windows, console systems, or Mac OS X; game development companies generally receive a lower return on investment when they support an operating system with a small market share. TheLinux Gamers' Game List is a long but selective list,^[47] andThe Linux Game Tome is a database with many entries that is less discriminating but has user comments and rankings.^[48]

There are few original open source games that have obtained notability, examples beingNetHack andTux Racer. Remakes and re-releases are more common, examples beingFreeciv andThe Ur-Quan Masters. In some cases, developers have released Linux ports of their games directly, withid Software recently releasingQuake 4. Independent companies have also taken on the task of porting prominent Windows games to Linux after their initial release.Loki Software was the first such company, founded in 1998, and superseded byLinux Game Publishing in 2001.WINE and the commercialCedega fork allow many Windows games to run natively under Linux, and virtual machines and low-level machine emulators provide binary compatibility for games designed for other platforms.

Library support for Linux gaming is provided directly byOpenGL andALSA, or bySDL, a cross-platform multimedia wrapper around system-dependent libraries. TheDRI project provides open source video card drivers, andNVIDIA, andATI also release binary kernel modules for their video cards. Linux runs on several game consoles, including theXbox,^[49]Playstation 2, 3, andGameCube,^[50] which allows game developers without an expensive game development kit to access console hardware.

Comparison with Windows[]

Main article:Comparison of Windows and Linux

Due to the prevalence of Microsoft Windows on personal computers from the mid-1990s onwards, a comparison between Windows and Linux became a common topic of conversation among computer enthusiasts. In the past, Linux and other free software projects have been frequently criticized for not going far enough to ensure ease of use.^[51] Since then, there have been numerous independent studies and articles which indicate that a modern Linux desktop using eitherGNOME orKDE is on par with Microsoft Windows, even in a business setting.^[52]

Although lack of application support is often cited as a reason to use Windows over Linux, compatibility layers such asWine orNdisWrapper andvirtual machines likeVirtualBox allow some Microsoft Windows applications and drivers to be used on Linux without requiring the vendor to adapt them. This allows users to more easily migrate from Windows to Linux since they can still run many of their Windows applications with little additional effort. Additionally, commercial software such asCrossOver have been developed which extend Wine to allow many commercial Windows applications to run in a Linux environment. In a similar fashion,Cygwin andMicrosoft Windows Services for UNIX make it possible for users of Windows to run some GNU and other software normally only available on Linux and other Unix-like systems.

Servers, supercomputers and embedded devices[]

Historically, Linux has mainly been used as aserver operating system, and has risen to prominence in that area;Netcraft reported in September 2006 that eight of the ten most reliable internet hosting companies run Linux on theirweb servers.^[53] This is due to its relative stability and long uptimes, and the fact that desktop software with a graphical user interface is often unneeded. Enterprise and non-enterprise Linux distributions may be found running on servers. Linux is the cornerstone of theLAMP server-software combination (Linux,Apache,MySQL,Perl/PHP/Python) which has achieved popularity among developers, and which is one of the more common platforms for website hosting.

Linux is commonly used as an operating system forsupercomputers. As ofJanuary 52007, out of the top 500 systems, 376 (75.2%) run Linux.^[54]

Due to its low cost and its high configurability, anembedded Linux is often used inembedded systems such as televisionset-top boxes,mobile phones, andhandheld devices. Linux has become a major competitor to the proprietarySymbian OS found in many mobile phones (16.7% ofsmartphones sold worldwide during 3Q, 2006 were using Linux^[55]), and it is an alternative to the dominantWindows CE andPalm OS operating systems onhandheld devices. The popularTiVo digital video recorder uses a customized version of Linux.^[56] Several networkfirewall androuter standalone products, including several fromLinksys, use Linux internally, using its advanced firewalling and routing capabilities. TheKorg OASYS and theYamaha Motif XSmusic workstations also run Linux.

Software development[]

Most Linux distributions support dozens ofprogramming languages. Core system software such as libraries and basic utilities are usually written in C. Enterprise software is often written in C, C++, Java, Perl, Ruby, or Python. The most common collection of utilities for building both Linux applications and operating system programs is found within theGNU toolchain, which includes theGNU Compiler Collection (GCC) and theGNU build system. Amongst others, GCC provides compilers forC,C++,Java, andFortran. The Linux kernel itself is written to be compiled with GCC.

Most distributions also include support forPerl,Ruby,Python and other dynamic languages. Examples of languages that are less common, but still well-supported, areC# via theMono project, andScheme. A number ofJava Virtual Machines 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 likeKaffe. The two main frameworks for developing graphical applications are those ofGNOME andKDE. These projects are based on theGTK+ andQtwidget toolkits, respectively, which can also be used independently of the larger framework. Both support a wide variety of languages. There are a number ofIntegrated development environments available includingAnjuta,Eclipse,KDevelop,MonoDevelop,NetBeans, andOmnis Studio while the traditional editorsVim andEmacs remain popular.^[57]

Although free and open source compilers and tools are widely used under Linux, there are also proprietary solutions available from a range of companies, including theIntel C++ Compiler, PathScale,^[58] Micro Focus COBOL,^[59]Franz Inc,^[60] and the Portland Group.^[61]

References[]

See also[]

• List of Linux distributions
• Comparison of Linux distributions
• List of Linux magazines
• The Cathedral and the Bazaar
• Total cost of ownership
• DistroWatch
• Linux software

Wikia[]

• Linux Wikia

External links[]

• The Linux Documentation Project — HOWTOs, FAQs and other guides
• The Linux Information Project (LINFO)
• Comprehensive Linux Textbook — free textbook
• Linux Knowledge Base and Tutorial
• The Linux Home Page at Linux Online — information and resources
• The Linux Kernel Archives — official site
• Linux Links - The Linux Portal — link site
• Linux Google search.
• The Linux Foundation.

References[]