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This article is about Linux-based operating systems, GNU/Linux, and related topics. See Linux kernel for the kernel itself. "Linux" is also the name of a German brand of washing powder.
the penguin, the Linux mascot]]

Linux is the name of a computer operating system and its kernel. It is the most famous example of free software and of open-source development.

Strictly, the name Linux refers only to the Linux kernel, but it is commonly used to describe entire Unix-like operating systems (also known as GNU/Linux) that are based on the Linux kernel and libraries and tools from the GNU project. Compilations of software that are based on these components, called Linux distributions, typically bundle large quantities of software, such as software development tools, databases, web servers like Apache, desktop environments like GNOME and KDE, and office suites like OpenOffice.org.

The kernel was originally developed for Intel 386 microprocessors but now supports a variety of computer architectures. It is deployed in applications ranging from personal computers to supercomputers and embedded systems such as mobile phoness and personal video recorders.

Initially developed and used mostly by individual enthusiasts, Linux has since gained the support of industry heavyweights such as IBM and Hewlett-Packard, overtaking many proprietary versions of Unix, and challenging the dominance of Microsoft Windows in some areas. Proponents and many analysts attribute this success to its vendor independence, low cost of implementation, security, and reliability.

Table of contents
1 History
2 Linux distributions
3 Scale of development efforts
4 Applications of Linux-based operating systems
5 Usability, market share and moving from Windows
6 References
7 See also
8 External links


See also: Timeline of Linux development

The Linux kernel was initially written as a hobby by Finnish university student Linus Torvalds while attending the University of Helsinki. It was designed to be like Minix, a kernel used for teaching operating system design that is designed for simplicity. The first version of Linux was released to the Internet in September 1991, with the second version following shortly thereafter in October [1]. Since, thousands of developers around the world have participated in the project. The essay The Cathedral and the Bazaar discusses the development model of the Linux kernel and similar software.

The history of Linux is closely tied to that of GNU, a prominent free-software project led by Richard Stallman. The GNU project was started in 1983 for developing a complete Unix-like operating system, including software development tools and user application programs, entirely of free software. By 1991, when the first version of the Linux kernel was written, the GNU project had produced all the necessary components of this system except the kernel. Torvalds and other early Linux-kernel developers adapted their kernel to work with the GNU components to create a fully functional operating system. The kernel is licensed under the GNU General Public License (GPL) but it is not part of the GNU Project.

Tux the penguin is the logo and mascot of Linux. The Linux trademark (SN: 1916230) is owned by Linus Torvalds, registered for "Computer operating system software to facilitate computer use and operation." The assignment of the trademark to Torvalds occurred after an attorney, one William R. Della Croce, Jr, in 1996 began sending letters to various Linux distributors claiming to own the Linux trademark and demanding royalties. The distributors rapidly pooled resources, appealed against the original trademark assignment and had it reassigned to Linus Torvalds. The licensing of the trademark is now handled by the Linux Mark Institute.

Pronunciation of Linux

According to Torvalds, the word Linux rhymes with "Minix" [1]:

"Li" is pronounced with a short [ee] sound: compare prInt, mInImal etc. 'nux' is also short, non-diphtong [sic], 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.

An audio file of Torvalds saying "Hello, this is Linus Torvalds, and I pronounce Linux as Linux" also exists [1]. Note that in English, "Linux" and "Minix" are often pronounced with a short I sound that is different from Torvalds' Finland-Swedish pronunciation of these words.

See also List of words of disputed pronunciation#Names for a discussion of the various ways "Linux" is pronounced.


Main article: GNU/Linux naming controversy

Because the GNU tools, an essential part of nearly all Linux distributions, stem from a long-standing free operating system project that predates the Linux kernel, Richard Stallman and the Free Software Foundation ask that the combined system (regardless of distribution) be referred to as GNU/Linux. Although some distributions do use this name, most notably Debian GNU/Linux, most simply refer to the system Linux. The distinction between Torvalds' kernel and entire Linux-based systems that contain the kernel is a perennial source of confusion, and the naming remains controversial.


Main article: SCO v. IBM

In March 2003, the SCO Group (SCO) filed a lawsuit against IBM claiming that IBM had contributed portions of SCO's intellectual property into the Linux kernel in violation of IBM's license to use UNIX, now claimed by SCO. Additionally, SCO sent letters to a number of companies warning that their use of Linux without a license from SCO may be actionable, and have claimed in the press that they would be suing individual Linux users. This controversy has more recently involved lawsuits by SCO against Novell, DaimlerChrysler (Dismissed in July, 2004), and AutoZone, and by Red Hat and others against SCO.

Linux distributions

Main article: Linux distribution

Linux is almost always used as part of a Linux distribution (distro). These are compiled by individuals, loose-knit teams, and various professional organizations. They include any number of additional system software and application programs, as well as certain processes to install these systems on a computer. Distributions are created for many different purposes, including localization, architecture support, real-time applications, and embedded systems, and there are some which deliberately include only free software.

A typical general-purpose distribution includes the Linux kernel, the GNU libraries and tools, command-line shellss, and a tremendous amount of application software, from office suites and the graphical X Window System to compilers, text editors, and scientific tools.

Scale of development efforts

More Than a Gigabuck: Estimating GNU/Linux's Size, a study of Red Hat Linux 7.1, found that this particular distribution contained 30 million source lines of code (SLOC). Using the Constructive Cost Model (COCOMO), the study estimated that this distribution required about eight thousand person-years of development time. Had all this software been developed by conventional proprietary means, it would have cost 1.08 billion dollars (year 2000 dollars) to develop in the United States.

The majority 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 contained 2.4 million lines of code, or 8% of the total.

In a later study, Counting potatoes: the size of Debian 2.2, the same analysis was performed for Debian GNU/Linux version 2.2. This distribution contained over fifty-five million source lines of code, and would have cost 1.9 billion dollars (year 2000 dollars) to develop by conventional proprietary means.

Applications of Linux-based operating systems

In the past, a Linux user needed significant knowledge of computers in order to install and configure his system. For this reason and, being attracted by access to the internals of the system, Linux users have traditionally tended to be more technologically oriented than users of Microsoft Windows and Mac OS, often revelling in the tag of "hacker" or "geek". This stereotype has been dispelled in recent years by the increasing user-friendliness and broader adoption of many Linux distributions. Linux has made considerable progress in server and special-purpose markets, such as image rendering and Web services, and is beginning to make inroads into the high volume desktop market.

Linux is the cornerstone of the so-called LAMP server-software combination (Linux, Apache, MySQL, Perl/PHP/Python) that has achieved widespread popularity among Web developers.

Linux is also often used in embedded system. Its low cost makes it ideal for such devices as the Simputer, a computer aimed especially at low-income populations in developing nations.

With desktop environments such as KDE and GNOME, Linux offers a user interface like that of the Apple Macintosh or Microsoft Windows in addition to other graphical environments and its traditional Unix-like command line interface. Graphical Linux software exists for many niches, although in many areas there is still greater breadth and quantity of proprietary software.

Usability, market share and moving from Windows

Once viewed as an operating system only computer geeks could use, Linux is today a much more user-friendly system, with many graphical interfaces and applications that bear a close resemblance to those of popular consumer operating systems.

Its market share for desktop usage remains small but growing. According to market research company IDC, 25% of servers and 2.8% of desktop computers were running Linux in 2002. However, argued advantages of Linux, such as lower cost, fewer security vulnerabilities, and lack of vendor lock-in have spurred a growing number of high-profile cases of mass adoption of Linux by corporations and governments for specific purposes.

Linux and other free software projects are frequently criticised for not going far enough in terms of ensuring usability, and the question of Linux's usability compared to Windows or the Macintosh remains hotly debated. For those only familiar with Windows or the Macintosh, using Linux may be difficult because many tasks do not work identically, and substantial differences remain in more sophisticated administrative and configuration tasks. It is also easier to find local technical support for Windows or MacOS than for Linux in many places.

Additionally, users might have to switch application software, and equivalents of some programs may not be available or there may be fewer options, as there are for computer games. However, more office and home applications now come with an installation. Because of reluctance to change and the fact that most computers come with Windows pre-installed, there is a slow adoption of new desktop operating systems.

There have been conflicting studies of Linux's usability and cost. Relevantive, a Berlin-based company specializing in consulting companies on the usability of software and Web services, concluded in 2003 that the usability of Linux for a set of specific desktop-related tasks was "nearly equal to Windows XP." On the other hand, Microsoft-sponsored studies by IDC have argued that Linux has a higher total cost of ownership (TCO) than Windows.

Linux distributions have been criticized for unpredictable development schedules, thus making enterprise users less comfortable with Linux than they might be with other systems (Marcinkowski, 2003). On the other hand, Microsoft release dates also have a reputation for slipping. The large number of choices of Linux distributions can also confuse users and software vendors.

The paper Why Open Source Software / Free Software (OSS/FS)? Look at the Numbers! identifies many quantitative studies of open source software, including market share, reliability, with many studies specifically examining Linux.

Several programs are purposed to make Windows applications run on Linux, with varying degrees of success. VMware and Win4Lin run Windows applications with near-perfect functionality but a severe speed penalty, similar to an emulator. WINE and WINE-based programs like Crossover Office and Transgaming Cedega use an application compatibility layer that is less complete but faster.


Difficulty of installation was initially a high barrier to adoption, but the installation process has been greatly eased in recent years, some distributions being easier to install than comparable versions of Windows.

With the adoption of Linux by several large personal computer manufacturers, computers with Linux distributions pre-installed have become available.

Some distributions allow Linux to be booted directly from a live CD without modifying the hard drive. CD ISO images for these and other distributions can usually be downloaded from the Internet, burneded to a CD and booted from the CD.

Linux can also be booted over a network or, for a minimal system, from a few floppy disks or network card.


Configuration of most settings is stored in a single directory called /etc, while user-specific settings are stored in hidden files in the user's home directory. A few programs use a configuration database instead of files.

There are a number of ways to change these settings. The easiest way to do this is by using tools provided by distributions such as SuSE's YaST or Mandrake's Control Center. Others, like Linuxconf and Gnome System Tools, are not distribution-specific. There are also many command line utilities for configuring programs. Since nearly all settings are stored in ordinary text files they can be configured by any text editor.


Technical support is provided by commercial suppliers and by other Linux users, usually in online forums, newsgroups and mailing lists. Linux User Groups (LUGs) all over the world assist many users, mostly locally, and often also hold "installfests" where users can install Linux with a nearby helping hand.

The business model of commercial suppliers is generally dependent on charging for support, especially for business users. Third-party commercial support is also readily available.


See also

Popular Linux distributions

There exist a very large number of Linux distributions. These are only some of the most popular:

Linux on Windows

Installing or running Linux on PCs with existing
Microsoft Windows installations, without a separate partition.

External links