Linux (IPA pronunciation: /ˈlɪnʊks/) is a Unix-like computer operating system. Linux is one of the most prominent examples of free software and open source development; its underlying source code can be modified, used, and redistributed by anyone, freely.[1]
The Linux kernel was first released to the public on 17 September 1991, for the Intel x86 PC architecture. The kernel was augmented with system utilities and libraries from the GNU project to create a usable operating system, which later led to the alternate term GNU/Linux.[2] Linux is now packaged for different uses in Linux distributions, which contain the kernel along with a variety of other software packages tailored to requirements.
Predominantly known for its use in servers, Linux has gained the support of corporations such as IBM[3], Sun Microsystems[4], Dell[5], Hewlett-Packard[6], and Novell[7], and is used as an operating system for a wide variety of computer hardware, including desktop computers, supercomputers,[8] and embedded devices such as mobile phones and routers.
Contents
History
Linus Torvalds, creator of the Linux kernel.
Linus Torvalds, creator of the Linux kernel.
The Unix operating system was conceived and implemented in the 1960s and first released in 1970. Its wide availability and portability meant that it was widely adopted, copied and modified by academic institutions and businesses, with its design being influential on authors of other systems.
The GNU Project, with the goal of creating a Unix-like, POSIX-compatible operating system composed entirely of free software,[9] began development in 1984, and a year later Richard Stallman had created the Free Software Foundation and wrote the first draft of the GNU 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 a Unix shell, and the upper level could be supplied by the X Window System, but development of the lower level, which consisted of a kernel, device drivers and daemons had stalled and was incomplete.[10]
MINIX, a Unix-like system intended for academic use, was released by Andrew S. Tanenbaum in 1987. While source code for the system was available, modification and redistribution were restricted. In addition, MINIX's 16-bit design was not well adapted to the increasingly cheap and popular Intel 386 architecture for personal computers.
In 1991, Linus Torvalds began to work on a non-commercial replacement for MINIX while he was attending the University of Helsinki.[11] This eventually became the Linux kernel. Torvalds intended Linux to be specifically tailored to the capabilities of the 32-bit Intel 386 platform.[12]
Linux was dependent on the Minix userspace at first. With code from the GNU system freely available, it was advantageous if this could be used with the fledgeling OS. Code licensed under the GNU GPL can be used in other projects, so long as they too are released under the GPL. In order to make the Linux kernel compatible with the components from the GNU project, Torvalds changed his original license (which prohibited commercial redistribution) to the GPLv2.[13] Linux and GNU developers worked to integrate GNU components with Linux. Thus Linux became a complete, fully functional free operating system.[10]
[edit] Pronunciation
In 1992, Torvalds explained how he pronounces the word Linux:
'li' is pronounced with a short [ee] sound: compare prInt, mInImal etc. 'nux' is also short, non-diphtong, like in pUt. It's partly due to minix: linux was just my working name for the thing, and as I wrote it to replace minix on my system, the result is what it is... linus' minix became linux.
—Linus Torvalds, comp.os.linux newsgroup[14]
Torvalds has made available an audio sample which indicates his own pronunciation, in English (/ˈlɪnʊks/)[15] and Swedish (/ˈlɪːnɤks/).[16] English speakers may also pronounce the name as [ˈlaɪnʌks],[17] /ˈlɪnʊks/, or /ˈlɪnəks/.[18]
See also: History of the Linux kernel#The name
[edit] Naming controversy
Richard Stallman, founder of the GNU project for a free operating system.
Richard Stallman, founder of the GNU project for a free operating system.
Main article: GNU/Linux naming controversy
The Free 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 as GNU/Linux or a Linux-based GNU system.[19] However, the media and population at large refers to this family of operating systems simply as Linux. While some distributors make a point of using the aggregate form, most notably Debian with the Debian 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.
[edit] Copyright, licensing and the Linux trademark
The Linux kernel and most GNU software are licensed under the GNU 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", "copyleft", or, pejoratively, a viral license. In 1997, Linus Torvalds stated, "Making Linux GPL'd was definitely the best thing I ever did."[20] Other software 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.
After more than ten years, the Free Software Foundation announced that they would be upgrading the GPL to version 3, citing increasing concerns with software patents and digital rights management (DRM).[21] In particular, DRM is appearing in systems running copyleft software, a phenomenon dubbed "tivoization" after digital video recorder maker Tivo's use of DRM in their Linux-based appliances.[22] Linus Torvalds has publicly stated on the Linux Kernel Mailing List that, based on the drafts of the license, he would not move the Linux kernel to GPL v.3, specifically citing the DRM provisions.[23][24]
In March 2003, the SCO Group filed a lawsuit 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 the Utah District Court ruling on July 3, 2006; 182 out of 294 items of evidence provided by SCO against IBM in discovery were dismissed.[25]
See also: SCO-Linux controversies
In 2004, Ken Brown, president of the Alexis de Tocqueville Institution, published Samizdat, a highly controversial book which, among other criticism of open source software, denied Torvalds' authorship of the Linux kernel (attributing it to Tanenbaum, instead). This was rebutted by Tanenbaum himself.[26][27]
In the United States, the name Linux is a trademark registered to Linus Torvalds.[28] Initially, nobody registered it, but on August 15, 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 to have the trademark assigned to Torvalds, and in 1997 the case was settled.[29] The licensing of the trademark has since been handled by the Linux Mark Institute. Torvalds has stated that he only trademarked the name to prevent someone else from using it, but was bound in 2005 by United 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.[30]
[edit] Milestones
The Linux and GNU 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 the KDE desktop environment by Matthias Ettrich in October 1996[31] followed by the comparable GNOME alternative by Miguel de Icaza in August 1997,[32] both based on the X11 windowing system developed at MIT. GNOME and KDE became Linux operating system shells, responsible for the direct contact with users.
* The release of the Netscape browser's source code on March 31, 1998, which kicked off the Mozilla project that would eventually give birth to the popular Mozilla Firefox browser.[33]
OpenOffice.org 2.2 - Writer : Word processor component of the multi-platform free software office suite.
OpenOffice.org 2.2 - Writer : Word processor component of the multi-platform free software office suite.
* The release of StarOffice by Sun Microsystems which in June 2000 became the base for the free software OpenOffice.org office suite,[34] a major event in the open source office world.[35] See also: list of free software.
* The growth of commercial interest in Linux is similarly marked by notable events: the launch in February 1998 of the Open Source Initiative; the announcement in July 1998 by Oracle Corporation that it would port its well-known database software to Linux and provide support for it; the IPOs of Red Hat on November 11, 1999 and VA Linux the following month which would create a speculative bubble; the wide-scale support of technology giant IBM that would spend millions of dollars on Linux, employing in 2005 close to 300 developers of the Linux kernel, and would organize starting in 2003 the legal defense for the SCO vs. Linux controversy against the attacks of the SCO Group that claimed copyright over the Linux kernel; and finally the acquisition in October and November 2003 of Ximian and then SuSE by the American technology company Novell.[36]
Today Linux is used in numerous domains, from embedded systems[37] to supercomputers,[38] and has secured a place in server installations with the popular LAMP application stack.[39] 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 of Linux distributions.
[edit] Development
A graphical history of Unix systems. Linux is a Unix-type system but its source code does not descend from the original Unix.
A graphical history of Unix systems. Linux is a Unix-type system but its source code does not descend from the original Unix.
A 2001 study of Red Hat Linux 7.1 found that this distribution contained 30 million source lines of code. Using the 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 means, it would have cost about 1.08 billion dollars (year 2000 U.S. dollars) to develop in the United States.[40]
Most of the code (71%) was written in the C programming language, but many other languages were used, including C++, Lisp, assembly language, Perl, Fortran, Python and various shell 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.[40]
In a later study, the same analysis was performed for Debian GNU/Linux version 2.2.[41] 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.
[edit] Programming on Linux
Most Linux distributions support dozens of programming 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[citation needed]. 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 C, C++, Java, and Fortran. The Linux kernel itself is written to be compiled with GCC.
Most also include support for Perl, Ruby, Python and other dynamic languages. Examples of languages that are less common, but still well-supported, are C# via the Mono project, and Scheme. A number of Java 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 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 widget toolkits, 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 environments available including Anjuta, Eclipse, KDevelop, Ultimate++, MonoDevelop, NetBeans, and Omnis Studio while the traditional editors Vim and Emacs remain popular.[42]
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 the Intel C++ Compiler, PathScale,[43] Micro Focus COBOL,[44] Franz Inc,[45] and the Portland Group.[46]
[edit] Philosophy
The copyleft logo. Modification and redistribution of copylefted works is permitted provided derivative works are also copylefted.
The copyleft logo. Modification and redistribution of copylefted works is permitted provided derivative works are also copylefted.
The primary difference between Linux and many other popular contemporary operating systems is that the Linux kernel and other components are free and open source software. Linux is not the only such operating system, although it is the most well-known and widely used one. Some free and open source software licences 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 used for the Linux kernel and many of the components from the GNU project.
[edit] Interoperability
Linux aims for interoperability with other operating systems such as (but not limited to) Microsoft Windows and Mac OS X, and by extension the software that runs on Linux aims for interoperability with other Linux and non-Linux software. As an operating system underdog competing with mainstream operating systems, Linux cannot rely on a monopoly 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 to POSIX, SUS, ISO, and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.[47][48][49]
A priority is placed on open 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 with proprietary 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, and APIs, they contribute to the robustness and adoption of Linux. In some cases, free software projects are the reference implementation of these protocols, examples being the Apache HTTP Server,[citation needed] and the X.org implementation of the X Window System.
Examples of standard conformance include Mozilla Firefox which adheres strictly to World Wide Web Consortium recommendations[50], Jabber which formed the basis for the XMPP standard recognized by the Internet Engineering Task Force in the domain of instant messaging, and office productivity suites such as OpenOffice.org and KOffice which brought to light the recent OpenDocument 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 through vendor lock-in, or the use of proprietary formats and communication protocols. Prime examples of the first category draw from the instant messaging war, which is ruled by multiprotocol software such as Pidgin, Kopete, and Trillian. The second category of software is exemplified by Microsoft Office and its widely used closed file formats, and the Common Internet File System protocol which allow for files and printers to be shared between different computers on a Windows network.
In these cases, interoperability depends on reverse engineering, which requires a substantial investment on the part of developers. The legal status of reverse engineering varies from country to country. Today, as a result of reverse engineering, OpenOffice.org can read most .doc files, and Samba 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 by digital rights management or Trusted Computing, or legally restricted by software patents or laws such as the European Copyright Directive and Digital Millennium Copyright Act.
[edit] Portability
Linux is a widely ported operating system. While the Linux kernel was originally designed only for Intel 80386 microprocessors, it now runs on a more diverse range of computer architectures than any other operating system—[51] from the hand-held ARM-based iPAQ to the mainframe IBM System z9, in devices ranging from supercomputers to mobile phones. Specialized distributions exist for less mainstream architectures. The ELKS kernel fork can run on Intel 8086 or Intel 80286 16-bit microprocessors, while the µClinux kernel may run on systems without a memory management unit including the Apple iPod. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as the iMac and PowerBook, Palm PDAs, GameCube, Xbox, Nintendo DS and even the Playstation Portable.
[edit] 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, as RedHat does with Fedora.
In many cities and regions, local associations known as Linux 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 many internet communities that seek to provide support to Linux users and developers. Most distributions and open source projects have a chatroom on the popular freenode IRC network that are open to anybody with an IRC client. Online forums are another means for support, with notable examples being LinuxQuestions.org and the Gentoo forums. Finally, every established free software project and Linux distribution has one or more mailing lists; commonly there will be a specific topic such as usage or development for a given list. The Linux Kernel Mailing List is a high-volume list where all Linux kernel development happens. SourceForge, Savannah, and Apache host many free and open source software projects using standard collaborative software.
Linux-based newsgroups are available via the Google Groups interface and also via news readers. There are also several technology websites with a Linux focus. Linux Weekly News is a weekly digest of Linux-related news; the Linux 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 the Free Software Foundation website.
People who contribute to free software are not all software developers, as exemplified by the GNOME and KDE 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 this open source culture are the Creative Commons movement initiated by Lawrence Lessig and the collaborative encyclopedia Wikipedia founded by Jimmy 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 include IBM, HP, Sun Microsystems, Novell, and Red 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 as 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.
The XO laptop project of One Laptop Per Child is creating a new and potentially much larger Linux community, planned to reach several hundred million schoolchildren and their families and communities in developing countries. Six countries have ordered a million or more units each for delivery in 2007 to distribute to schoolchildren at no charge. Google, Red Hat, and eBay are major supporters of the project.
[edit] Distribution
Linux Distro Genesis, timeline representing the development of various Linux distributions.
Linux Distro Genesis, timeline representing the development of various Linux 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 a Linux distribution.
A Linux 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 and application software in the form of packages, 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. A boot loader: A piece of software that can be loaded by the system's firmware (bios in the case of a PC) and then perform the actions needed to load and start the linux kernel. Often a menu is presented that will allow the user to select which operating system to load. The most common bootloaders for the PC architecture are LILO or GRUB.
2. The Linux kernel: The core or heart of the operating system. The name of the OS comes from here.
3. Boot scripts, disk/storage maintenance tools, authentication tools, and scripting languages: They are administration tools, usually considered part of the operating system.
4. GNU C Library and, optionally, the GNU Compiler Collection: The development tools, used to assist or develop applications.
5. GNU bash shell, X Window System networking and display protocol and an accompanying desktop environment such as KDE, GNOME,or Xfce: The shells and graphic systems, used for interacting with the user.
6. Application software packages: There are hundreds of them in most distributions (thousands in bigger distributions, like Gentoo, Fedora, Debian, etc.) , from office suites to webservers to media players to 3D computer graphics software to text editors, and scientific programs. They may come in some storage medium, like a DVD, or, more commonly, be available in on-line repositories.
7. Package management software: These are created specifically for the distribution, for organizing all software, seamless downloading and installing, upgrading and managing security issues.
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 for 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.[52]
[edit] Interface
The command line, favoured by some Linux power users
The command line, favoured by some Linux power users
[edit] Command line interface (CLI)
Linux includes by default a command line interface (CLI) as part of its Unix-like functionality. Distributions specialized for servers or administration may use the CLI as their only interface, for the absence of a graphical user interface (GUI) reduces system resource consumption. As well, Linux machines can run without a monitor attached. Such "headless systems" may be controlled either through X11 remotely, or the CLI must be used via a protocol such as SSH or telnet. On local networks, remote X11 usage is generally acceptable, but over long distances network latency can make a graphical interface 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 frequently present 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.
Many important programs do not have a GUI, including most of the GNU userland. This comes from the Unix 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 graphical terminal emulator programs, including xterm, rxvt, aterm, gnome-terminal, and konsole. For these programs, the X11 copy and paste mechanism can facilitate communication between the terminal and GUI applications.
A misconception about Linux states that Linux is almost exclusively CLI-driven. Despite the importance of CLI in Linux, most, if not all, of the tasks can be carried out through GUIs, much like Windows, OSX, Solaris, or any other commercial operating system.[citation needed]
[edit] X window managers
Window Maker 0.91.0, showing the XMMS music player, xterm terminal emulator, and Window Maker application menu and preferences.
Window Maker 0.91.0, showing the XMMS music player, xterm terminal emulator, and Window Maker application menu and preferences.
Main article: X window manager
The traditional GUI for a Linux operating system is based on a stand-alone X window manager such as FVWM, Enlightenment, or Window 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 the X window system.
This model contrasts with that of platforms such as Mac 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 consistent look and feel to the user. Because the X window managers only manage the placement of windows, their decoration, and some inter-process communication, the look and feel of individual applications may vary widely, especially if they use different graphical user interface toolkits.
[edit] Desktop environments
GNOME 2.16, showing the Nautilus file manager and the gedit text editor.
GNOME 2.16, showing the Nautilus file manager and the gedit text editor.
Main article: X Window System desktop environment
The use of window managers by themselves declined with the rise of Linux desktop environments. They combine a window manager with a suite of standard applications that adhere to human interface guidelines. While a window manager is analogous to the Aqua user interface for Mac OS X, a desktop environment is analogous to Aqua with all of the default Mac OS X graphical applications and configuration utilities. Initially, CDE was available as a proprietary solution. It was never popular on Linux, due to its cost and licensing restrictions.[citation needed] KDE, which was announced in 1996, has become the second most popular desktop environment[citation needed]. GNOME and Xfce were both announced in 1997. Both are now based on the GTK toolkit. As of 2007, GNOME is the default desktop environment in most major distributions, including Debian, Ubuntu, RHEL, and Fedora[citation needed].
[edit] Applications
[edit] Desktop
KDE 3.5, showing the Kontact personal information manager and Konqueror file manager, web browser, and file viewer.
KDE 3.5, showing the Kontact personal information manager and Konqueror file manager, web browser, and file viewer.
Main article: Desktop Linux
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: OpenOffice.org. It may be useful to compare office suites.
* Internet: aMule, Azureus, Evolution, Firefox, Thunderbird, Opera, Pidgin.
* Multimedia: Amarok, MPlayer, Totem, VLC, Xine, XMMS.
* Graphics: Blender, GIMP, Inkscape, Scribus.
Although in specialized application domains such as desktop publishing and professional 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.[53] Furthermore, it is uncommon[citation needed] 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.[citation needed] A growing amount of proprietary desktop software is also supported under Linux,[54] examples being Adobe Flash Player, Acrobat Reader, Nero Burning ROM, Opera, RealPlayer, and Skype. In the field of animation and visual effects, most highend software, such as AutoDesk Maya, Softimage XSI and Apple Shake are available both for Linux, Windows and/or MacOS X. Additionally, Crossover is a commercial solution based on the open source WINE project that supports running Windows versions of Microsoft Office and Photoshop.
[edit] Games
Vega Strike, a space flight game.
Vega Strike, a space flight game.
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. The Linux Gamers' Game List is a long but selective list,[55] and The Linux Game Tome is a database with many entries that is less discriminating but has user comments and rankings.[56]
There are few original open source games that have obtained notability, examples being NetHack and Tux Racer. Remakes and re-releases are more common, examples being Freeciv and The Ur-Quan Masters. In some cases, developers have released Linux ports of their games directly, with id Software releasing both Quake 3 Arena and Quake 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 by Linux Game Publishing in 2001. Wine and the commercial Cedega 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 by OpenGL and ALSA, or by SDL, a cross-platform multimedia wrapper around system-dependent libraries. The DRI project provides open source video card drivers, and NVIDIA, and ATI also release binary kernel modules for their video cards. Linux works on several game consoles, including the Xbox,[57] PlayStation 2, PlayStation 3, and GameCube,[58] which allows game developers without an expensive game development kit to access console hardware.
Additionally, some SEGA arcade machines, specifically the Sega Lindbergh series, run Linux. However, these machines have DRMs built in that prevent Linux users from running these games on other Linux machines.
[edit] Servers, supercomputers and embedded devices
Historically, Linux has mainly been used as a server 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 their web servers.[59] 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 the LAMP 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 for supercomputers. As of January 5, 2007, out of the top 500 systems, 376 (75.2%) run Linux.[60]
Due to its low cost and its high configurability, an embedded Linux is often used in embedded systems such as television set-top boxes, mobile phones, routers, and handheld devices. Linux has become a major competitor to the proprietary Symbian OS found in many mobile phones (16.7% of smartphones sold worldwide during 2006 were using Linux[61]), and it is an alternative to the dominant Windows CE and Palm OS operating systems on handheld devices. The popular TiVo digital video recorder uses a customized version of Linux.[62] Several network firewall and router standalone products, including several from Linksys, use Linux internally, using its advanced firewalling and routing capabilities. The Korg OASYS and the Yamaha Motif XS music workstations also run Linux.
[edit] Market share and uptake
Main articles: Linux adoption and Usage share of desktop operating systems
Many quantitative studies of open source software focus on topics including market share and reliability, with numerous studies specifically examining Linux.[63] 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.[64] 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.[citation needed] According to market research company IDC, 25% of servers and 2.8% of desktop computers ran Linux as of 2004.[65] The estimate of these numbers is driven by website traffic analysis, which may be complicated by two factors. First, many web browsers can modify their identity, either by default or via user action, by exploiting the user agent string, so as not to be blocked by websites that refuse to interact with browsers other than Internet Explorer running under Microsoft Windows[66]. Second, a Linux system may be configured not to communicate this information for privacy and security reasons.
The difficulty of measuring the exact number of deployments becomes apparent when looking at IDC's report for Q1 2007, which says that Linux now holds 12.7% of the overall server market.[67] This estimate was based on the number of Linux servers sold by various companies, but since Linux servers are inherently free this number says nothing about the actual market share of the operating system, just how much money companies are making from selling it.
It has been alleged that people regard Linux as suitable mostly for computer experts because mainstream computer magazine reporters cannot explain what Linux is in a meaningful way, as they lack real life experience using it.[68] Furthermore, 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. 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,[69] low cost, and freedom from vendor lock-in.[70]
[edit] Criticisms
Linux has been criticized for being inadequate for desktop use, notably because of the perceived availability of only questionable alternatives to widely-used applications (especially office suites) and hardware support issues,[71] which is claimed to be particularly problematic for laptop users as they tend to use many proprietary devices. A steep learning curve of Linux beyond basic use, various incompatibilities with other operating systems, and difficulty involved with setting up hardware are also notable complaints. Further, Linux has been accused of being "not ideal" for intermediate power users.[72]