Linux
Tux, the penguin, mascot of Linux.
OS family	Unix-like
Kernel type	Monolithic kernel
License	GNU General Public License and others
Working state	Current

Linux (commonly pronounced IPA: /ˈlɪnəks/ in English; variants exist^[1]) is the name usually given to any Unix-like computer operating system that uses the Linux kernel. A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming In Computer science, the kernel is the central component of most computer Operating systems (OS A monolithic kernel is a kernel architecture where the entire kernel is run in Kernel space in Supervisor mode. A software license (or software licence in commonwealth usage is a Legal instrument governing the usage or redistribution of copyright protected software A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination Linux is an operating system kernel used by a family of Unix-like Operating systems These are popularly termed Linux operating systems and Linux is one of the most prominent examples of free software and open source development: typically all underlying source code can be freely modified, used, and redistributed by anyone. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Open source is a development methodology which offers practical accessibility to a product's source (goods and knowledge In Computer science, source code (commonly just source or code) is any sequence of statements or declarations written in some Human-readable ^[2]

The name "Linux" comes from the Linux kernel, started in 1991 by Linus Torvalds. Linux is an operating system kernel used by a family of Unix-like Operating systems These are popularly termed Linux operating systems and Linus Benedict Torvalds ( ˈtuːrvalds born December 28 1969 in Helsinki, Finland) is a Finnish software engineer The system's utilities and libraries usually come from the GNU operating system, announced in 1983 by Richard Stallman. System software is any Computer software which manages and controls Computer hardware so that Application software can perform a task In Computer science, a library is a collection of Subroutines used to develop Software. GNU ( pronounced) is a computer Operating system composed entirely of Free software. Richard Matthew Stallman (born March 16 1953 often abbreviated " rms " is an American software freedom activist The GNU contribution is the basis for the alternative name GNU/Linux. The GNU/Linux naming controversy is a dispute among members of the Free and open source software community. ^[3]

Predominantly known for its use in servers, Linux is supported by corporations such as Dell, Hewlett-Packard, IBM, Novell, Oracle Corporation, Red Hat, and Sun Microsystems. A server is a Computer dedicated to providing one or more services over a computer network typically through a request-response routine The multinational technology company Dell Inc develops manufactures sells and supports Personal computers and other computer-related products International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology Novell Inc ( is a global Software Corporation based in the United States specializing in enterprise operating systems such as SUSE Oracle Corporation ( specializes in developing and marketing Enterprise software products — particularly Database management systems In 2007 Oracle ranked In Computing, Red Hat Inc ( is a company dedicated to Free and open source software, and a major Linux distribution vendor Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services It is used as an operating system for a wide variety of computer hardware, including desktop computers, supercomputers,^[4], and embedded devices such as E-book readers, video game systems (PlayStation 2, PlayStation 3 and XBox^[5]), mobile phones and routers. Hardware is a general term that refers to the physical artifacts of a Technology. A desktop computer is a Personal computer (PC in a form intended for regular use at a single location as opposed to a mobile Laptop or portable computer A supercomputer is a Computer that is at the frontline of processing capacity particularly speed of calculation (at the time of its introduction An embedded system is a special-purpose Computer system designed to perform one or a few dedicated functions often with Real-time computing constraints An e-book device, sometimes also called an e-book reader, is a device used to display E-books It may be a device specifically designed for that purpose or one intended The Xbox is a sixth-generation Video game console produced by Microsoft Corporation. A router ('rautər in the USA 'rutər in the UK and Ireland, or either pronunciation in Australia and Canada is a Computer whose software and hardware are usually

History

See also: History of Linux

Richard Stallman, founder of the GNU project

The Unix operating system was conceived and implemented in the 1960s and first released in 1970. The Linux kernel has been marked by constant growth throughout its history Richard Matthew Stallman (born March 16 1953 often abbreviated " rms " is an American software freedom activist The GNU Project is a Free software, Mass collaboration project announced in 1983 by Richard Stallman. Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer 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. See also Software portability In Computer science, porting is the process of adapting software so that an executable program can be created

The GNU Project, started in 1984, had the goal of creating a "complete Unix-compatible software system"^[6] made entirely of free software. The GNU Project is a Free software, Mass collaboration project announced in 1983 by Richard Stallman. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified In 1985, Richard Stallman created the Free Software Foundation and developed the GNU General Public License (GNU GPL). Richard Matthew Stallman (born March 16 1953 often abbreviated " rms " is an American software freedom activist The Free Software Foundation ( FSF) is a Non-profit corporation founded by Richard Stallman on 4 October 1985 to support the Free software movement Many of the programs required in an OS (such as libraries, compilers, text editors, a Unix shell, and a windowing system) were completed by the early 1990s, although low level elements such as device drivers, daemons, and the kernel were stalled and incomplete. A compiler is a Computer program (or set of programs that translates text written in a computer language (the source language) into another A text editor is a type of program used for editing plain Text files Text editors are often provided with Operating systems or software development A Unix shell, is a command line shell that provides the traditional User interface for the Unix Operating system and for Unix-like In computing a device driver or software driver is a Computer program allowing higher-level computer programs to interact with a Hardware device In Unix and other computer multitasking Operating systems a daemon (ˈdiːmən or /ˈdeɪmən/ is a Computer program that runs in the background In Computer science, the kernel is the central component of most computer Operating systems (OS ^[7] 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. ^[8]

MINIX

Linus Torvalds, creator of the Linux kernel. Linus Benedict Torvalds ( ˈtuːrvalds born December 28 1969 in Helsinki, Finland) is a Finnish software engineer Linux is an operating system kernel used by a family of Unix-like Operating systems These are popularly termed Linux operating systems and

MINIX, a Unix-like system intended for academic use, was released by Andrew S. Tanenbaum in 1987. MINIX is a Unix-like computer Operating system based on a Microkernel architecture. Andrew Stuart "Andy" Tanenbaum (sometimes referred to by the handle ast) (born 1944 is a Professor of Computer science at the Vrije The source code for MINIX 1. 0 was printed in his book Operating Systems: Design and Implementation. While easily available, modification and redistribution were restricted (though that is not the case today). The code was covered by the copyrights of the textbook, published by Prentice Hall. Prentice Hall is a leading educational publisher It is an Imprint of Pearson Education Inc In addition, MINIX's 16-bit design was not well adapted to the 32-bit design of the increasingly cheap and popular Intel 386 architecture for personal computers. The range of Integer values that can be stored in 32 bits is 0 through 4294967295 or −2147483648 through 2147483647 using Two's complement encoding

In 1991, Torvalds began to work on a non-commercial replacement for MINIX while he was attending the University of Helsinki. The University of Helsinki (Helsingin yliopisto Helsingfors universitet is a University located in Helsinki, Finland since 1829 but founded ^[9] This eventually became the Linux kernel. Linux is an operating system kernel used by a family of Unix-like Operating systems These are popularly termed Linux operating systems and

In 1992, Tanenbaum posted an article on Usenet claiming Linux was obsolete. Usenet, a Portmanteau of "user" and "network" is a world-wide distributed Internet discussion system In the article, he criticized the operating system as being monolithic in design and being tied closely to the x86 architecture and thus not portable, which he described as "a fundamental error". A monolithic kernel is a kernel architecture where the entire kernel is run in Kernel space in Supervisor mode. ^[10] Tanenbaum suggested that those who wanted a modern operating system should look into one based on the microkernel model. A microkernel is a minimal Computer Operating system kernel which in its purest form provides no operating-system services at all only the The posting elicited the response of Torvalds, which resulted in a well known debate over the microkernel and monolithic kernel designs. The Tanenbaum-Torvalds debate is a debate between Andrew S Tanenbaum and Linus Torvalds, regarding Linux and kernel architecture in general ^[10]

Linux was dependent on the MINIX user space at first. "kernel space" redirects here For mathematical definition see Null space. 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. ^[11] Linux and GNU developers worked to integrate GNU components with Linux to make a fully functional and free operating system. ^[7]

Commercial and popular uptake

Today Linux is used in numerous domains, from embedded systems^[12] to supercomputers,^[13] and has secured a place in web server installations with the popular LAMP application stack. An embedded system is a special-purpose Computer system designed to perform one or a few dedicated functions often with Real-time computing constraints A supercomputer is a Computer that is at the frontline of processing capacity particularly speed of calculation (at the time of its introduction A server is a Computer dedicated to providing one or more services over a computer network typically through a request-response routine The Acronym LAMP refers to a Solution stack of software usually Free and open source software, used to run dynamic Web sites or servers ^[14] 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 distributions. A Linux distribution (also called GNU/Linux by distributions such as Debian, Fedora, Ubuntu, Linux Mint, Mandriva and

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-diphthong, 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^[15]

Torvalds has made available an audio sample which indicates his own pronunciation, in English and Swedish. ^[16][17] However, an interview from the 2001 documentary Revolution OS indicates that his preferred pronunciation has slightly changed. Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. Revolution OS is a 2001 Documentary film made in the United States, directed by J ^[18]

Many English speakers tend to pronounce the name as [ˈlɪnʊks] or [ˈlɪnəks].

Design

Linux is a modular Unix-like operating system. A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming It derives much of its basic design from principles established in Unix during the 1970s and 1980s. Linux uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. A monolithic kernel is a kernel architecture where the entire kernel is run in Kernel space in Supervisor mode. Linux is an operating system kernel used by a family of Unix-like Operating systems These are popularly termed Linux operating systems and For an account of the words periphery and peripheral as they are used in biology sociology politics computer hardware and other fields see the In Computing, a file system (often also written as filesystem) is a method for storing and organizing Computer files and the data they contain to make Device drivers are integrated directly with the kernel. In computing a device driver or software driver is a Computer program allowing higher-level computer programs to interact with a Hardware device

Much of Linux's higher-level functionality is provided by separate projects which interface with the kernel. The GNU userland is an important part of most Linux systems, providing the shell and Unix tools which carry out many basic operating system tasks. Userland refers to an application space that is external to the kernel and is protected by Privilege separation. In computing a shell is a piece of software that provides an interface for users This is a list of UNIX utilities as specified by IEEE Std 1003 On top of the kernel, these tools form a Linux system with a graphical user interface that can be used, usually running in the X Window System.

User interface

See also: User interface

Linux can be controlled by one or more of a text-based command line interface (CLI), graphical user interface (GUI) (usually the default for desktop), or through controls on the device itself (common on embedded machines). The user interface (or Human Computer Interface) is the aggregate of means by which people&mdash the users '&mdash interact with the System

On desktop machines, KDE, GNOME and Xfce are the most popular user interfaces,^[19] though a variety of other user interfaces exist. KDE ( K Desktop Environment) (ˌkeɪdiːˈiː is a Free software project which aims to be a powerful system for an easy-to-use Desktop environment. A gnome is a Mythical creature characterized by its extremely small size and subterranean lifestyle Xfce ( ɛf siː iː is a Free software Desktop environment for Unix and other Unix-like platforms such as Linux, Solaris Most popular user interfaces run on top of the X Window System (X), which provides network transparency, enabling a graphical application running on one machine to be displayed and controlled from another. Network Transparency in its most general sense refers to the ability of a protocol to transmit data over the network in a manner which is transparent (invisible to those using

Other GUIs include X window managers such as FVWM, Enlightenment, Fluxbox and Window Maker. An X window manager is a Window manager which runs on top of the X Window System, a Windowing system mainly used on Unix-like systems The F Virtual Window Manager (The Enlightenment, also known simply as E, is a Free software / Open source Window manager for the X Window System which can be used alone In Unix computing Fluxbox is an X window manager based on Blackbox 0 Window Maker is a Window manager for the X Window System, allowing graphical applications to be run on Unix-like operating-systems The window manager provides a means to control the placement and appearance of individual application windows, and interacts with the X window system.

A Linux system usually provides a command line interface of some sort through a shell, which is the traditional way of interacting with a Unix system. In computing a shell is a piece of software that provides an interface for users A Linux distribution specialized for servers may use the CLI as its only interface. A “headless system” run without even a monitor can be controlled by the command line via a protocol such as SSH or telnet. Secure Shell or SSH is a Network protocol that allows data to be exchanged using a Secure channel between two networked devices Telnet ( Tel ecommunication net work is a Network protocol used on the Internet or local area network (LAN connections

Most low-level Linux components, including the GNU Userland, use the CLI exclusively. Userland refers to an application space that is external to the kernel and is protected by Privilege separation. The CLI is particularly suited for automation of repetitive or delayed tasks, and provides very simple inter-process communication. Inter-Process Communication ( IPC) is a set of techniques for the exchange of data among two or more threads in one or more processes. A graphical terminal emulator program is often used to access the CLI from a Linux desktop. A terminal emulator, terminal application, term, or tty for short is a program that emulates a "dumb" video terminal within some other

Development

Main article: Linux distribution

A summarized history of Unix-like operating systems showing Linux's origins. A Linux distribution (also called GNU/Linux by distributions such as Debian, Fedora, Ubuntu, Linux Mint, Mandriva and A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming 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. POSIX (ˈpɒzɪks or "Portable Operating System Interface" is the collective name of a family of related standards specified by the IEEE to define Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer MINIX is a Unix-like computer Operating system based on a Microkernel architecture.

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 an operating system kernel used by a family of Unix-like Operating systems These are popularly termed Linux operating systems and Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Open source software (OSS began as a marketing campaign for Free software. Linux is not the only such operating system, although it is the best-known and most widely used. 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. A free software licence is a Software licence which grants recipients rights to modify and redistribute the Software which would otherwise be prohibited by Copyright An open source license is a copyright License for Computer software that makes the source code available under terms that allow for modification and redistribution Copyleft is a play on the word Copyright and describes the practice of using copyright law to remove restrictions on distributing copies and modified versions 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. The GNU Project is a Free software, Mass collaboration project announced in 1983 by Richard Stallman.

Linux systems adhere to POSIX,^[20] SUS,^[21] ISO and ANSI standards where possible. POSIX (ˈpɒzɪks or "Portable Operating System Interface" is the collective name of a family of related standards specified by the IEEE to define The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix To date, however, only the Linux-FT distribution has been POSIX. 1 certified. ^[22]

Free software projects, although developed in a collaborative fashion, are often produced independently of each other. Collaboration is a recursive process where two or more people or organizations work together toward an intersection of common goals — for example an intellectual However, because the software licenses explicitly permit redistribution there is a basis for larger scale projects that collect the software produced by stand-alone projects and make this software available together in a Linux distribution. A Linux distribution (also called GNU/Linux by distributions such as Debian, Fedora, Ubuntu, Linux Mint, Mandriva and

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. A Linux distribution (also called GNU/Linux by distributions such as Debian, Fedora, Ubuntu, Linux Mint, Mandriva and 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. Application software is a subclass of Computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform 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.

Community

See also: Free software community

A command line session using bash

Linux is largely driven by its developer and user communities. The free software community is an informal term referring to the users and developers of Free software as well as supporters of the Free software movement. Bash is a Free software Unix shell written for the GNU Project. Some vendors develop and fund their distributions on a volunteer basis, Debian being a well-known example. Debian ( pronounced) is a computer Operating system composed entirely of Free and open source software. Others maintain a community version of their commercial distributions, as Red Hat does with Fedora. In Computing, Red Hat Inc ( is a company dedicated to Free and open source software, and a major Linux distribution vendor The Fedora Operating system is an RPM -based general purpose Linux distribution, developed by the community-supported Fedora Project and sponsored

In many cities and regions, local associations known as Linux Users Groups (LUGs) seek to promote Linux and by extension free software. A Linux User Group or Linux Users' Group ( LUG) is a private generally non-profit or not-for-profit organization that provides support and/or education for 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. The Internet is a global system of interconnected Computer networks Most distributions and open source projects have IRC chatrooms or newsgroups. A newsgroup is a Repository usually within the Usenet system for messages posted from many users in different locations Online forums are another means for support, with notable examples being LinuxQuestions.org and the Gentoo forums. An, or message board, is a Bulletin board system in the form of a discussion site LinuxQuestionsorg (commonly abbreviated LQ) is a community-driven self-help site for Linux users The Gentoo Linux Operating system (ˈdʒɛntuː is a Linux distribution based on the Portage Package management system. Linux distributions host mailing lists; commonly there will be a specific topic such as usage or development for a given list. A mailing list is a collection of names and addresses used by an individual or an organization to send material to multiple recipients

There are 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 the Linux kernel and its relationship with GNU on the GNU project's website. Linux Journal is a monthly Magazine published by Belltown Media Inc Slashdot, often abbreviated as /, is a technology-related news Website owned by SourceForge Inc Groklaw is an award-winning website covering legal news of interest to the free and open-source software community GNU ( pronounced) is a computer Operating system composed entirely of Free software. The GNU Project is a Free software, Mass collaboration project announced in 1983 by Richard Stallman. Print magazines on Linux often include cover disks including software or even complete Linux distributions. Magazines, periodicals or serials are Publications generally published on a regular schedule containing a variety of articles, generally Covermount (sometimes written cover mount) is the name given to Storage media (containing Software and or Audiovisual media) or other products ^[23][24]

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 Dell, IBM, HP, Sun Microsystems, Novell, and Red Hat. The multinational technology company Dell Inc develops manufactures sells and supports Personal computers and other computer-related products International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services Novell Inc ( is a global Software Corporation based in the United States specializing in enterprise operating systems such as SUSE In Computing, Red Hat Inc ( is a company dedicated to Free and open source software, and a major Linux distribution vendor The free software licenses on which Linux are based explicitly accommodate and encourage commercialization; the relationship between Linux as a whole and individual vendors may be seen as symbiotic. This article is about the biological phenomenon for other uses see Symbiosis (disambiguation The term symbiosis (from the Greek 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 languages. A programming language is an Artificial language that can be used to write programs which control the behavior of a machine particularly a Computer. 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. The GNU toolchain is a blanket term for a collection of Programming tools produced by the GNU Project. The GNU Compiler Collection (usually shortened to GCC) is a set of Compilers produced for various Programming languages by the GNU Project The GNU build system, also known as the Autotools, is a suite of Programming tools produced by the GNU project. Amongst others, GCC provides compilers for Ada, C, C++, Java, and Fortran. Ada is a structured, Statically typed, imperative, and object-oriented high-level computer Programming language tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured C++ (" C Plus Plus " ˌsiːˌplʌsˈplʌs is a general-purpose Programming language. Fortran (previously FORTRAN) is a general-purpose, procedural, imperative Programming language that is especially suited to The Linux kernel itself is written to be compiled with GCC. Proprietary compilers for Linux include the Intel C++ Compiler and IBM XL C/C++ Compiler. Proprietary software is Computer software on which the producer has set restrictions on use private modification copying, or republishing. Intel C++ Compiler (also known as icc or icl) describes a group of C / C++ Compilers from Intel.

Most distributions also include support for Perl, Ruby, Python and other dynamic languages. NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below Ruby is a dynamic, reflective, general purpose Object-oriented programming language that combines syntax inspired by Perl with Smalltalk Python is a general-purpose High-level programming language. Its design philosophy emphasizes programmer productivity and code readability This article is about a class of programming languages for the method for reducing the runtime of algorithms see Dynamic programming. Examples of languages that are less common, but still well-supported, are C# via the Mono project, and Scheme. C# (pronounced C Sharp is a Multi-paradigm Mono is a project led by Novell (formerly by Ximian) to create an Ecma standard compliant. Scheme is a Multi-paradigm programming language. It is one of the two main dialects of Lisp and supports a number of programming paradigms but is 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. A Java Virtual Machine ( JVM) is a set of computer software programs and data structures which use a Virtual machine HotSpot is the primary Java Virtual Machine for desktops and servers produced by Sun Microsystems. Kaffe is a Clean room design of a Java Virtual Machine. It comes with a subset of the Java 2 Platform Standard Edition Java API and Tools The two main frameworks for developing graphical applications are those of GNOME and KDE. A gnome is a Mythical creature characterized by its extremely small size and subterranean lifestyle KDE ( K Desktop Environment) (ˌkeɪdiːˈiː is a Free software project which aims to be a powerful system for an easy-to-use Desktop environment. These projects are based on the GTK+ and Qt widget toolkits, respectively, which can also be used independently of the larger framework. GTK+, or The GIMP Toolkit, is a Cross-platform Widget toolkit for creating Graphical user interfaces It is one of the most popular toolkits Qt (pronounced "cute" by its creators is a Cross-platform application development framework widely used for the development of GUI programs (in which A widget toolkit, widget library, or GUI toolkit is a set of widgets for use in designing applications with Graphical user interfaces (GUIs Both support a wide variety of languages. There are a number of Integrated development environments available including Anjuta, Code::Blocks, Eclipse, KDevelop, Lazarus, MonoDevelop, NetBeans, and Omnis Studio while the long-established editors Vim and Emacs remain popular. In Computing, an integrated development environment ( IDE) is a Software application that provides comprehensive facilities to Computer programmers Anjuta is an Integrated development environment for the C and C++ computer Programming languages written for the GNOME project Not to be confused with the computer programming term Code block. In Computing, Eclipse is a Software platform comprising extensible Application frameworks tools and a Runtime library for Software KDevelop is a Free software Integrated development environment for the KDE desktop environment for Unix-like computer Operating systems This article concerns the software IDE named Lazarus. For other uses of the name see Lazarus (disambiguation. MonoDevelop is an open source Integrated development environment for the Linux platform primarily targeted for the development of software that uses both the NetBeans refers to both a platform for the development Vim is a Text editor first released by Bram Moolenaar in 1991 for the Amiga computer Emacs is a class of feature-rich Text editors usually characterized by their extensibility ^[25]

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 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. In Computer engineering, computer architecture is the conceptual design and fundamental operational structure of a Computer system Embedded Linux is the use of a Linux Operating system in Embedded computer systems such as Mobile phones Personal digital assistants In Computer science, real-time computing (RTC is the study of hardware and software systems that are subject to a "real-time constraint"—i Furthermore, some distributions deliberately include only free software. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use. ^[26]

Linux is a widely ported operating system. See also Software portability In Computer science, porting is the process of adapting software so that an executable program can be created 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: in the hand-held ARM-based iPAQ and the mainframe IBM System z9, in devices ranging from mobile phones and wristwatches^[27] to supercomputers. A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated In Computer engineering, computer architecture is the conceptual design and fundamental operational structure of a Computer system The ARM architecture (previously the Advanced RISC Machine, and prior to that Acorn RISC Machine) is a 32-bit RISC processor architecture This article is about the iPAQ PDA; for the iPAQ Desktop Personal Computer see IPAQ (desktop computer. Mainframes (often colloquially referred to as Big Iron) are Computers used mainly by large organizations for critical applications typically bulk data International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology IBM System z9 is a line of IBM mainframes. It was announced on July 25 2005 and the first models A watch is a timepiece that is made to be worn on a person The term now usually refers to a wristwatch, which is worn on the wrist with a strap or Bracelet. A supercomputer is a Computer that is at the frontline of processing capacity particularly speed of calculation (at the time of its introduction ^[28] 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 fork may run on systems without a memory management unit. The Embeddable Linux Kernel Subset (ELKS is a Unix-like operating system kernel that can run on Intel 8086 -compatible Microprocessors ELKS In Software engineering, a project fork happens when developers take a copy of Source code from one software package and start independent development The 8086 is a 16-bit Microprocessor chip designed by Intel and introduced on the market in 1978 which gave rise to the X86 architecture The Intel 286, introduced on February 1, 1982, (originally named 80286, and also called iAPX 286 in the programmer's manual A memory management unit ( MMU) sometimes called paged memory management unit ( PMMU) is a Computer hardware component responsible for handling The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as Macintosh computers, PDAs, video game consoles, portable music players, and mobile phones. Macintosh, commonly nicknamed Mac is a Brand name which covers several lines of Personal computers designed developed and marketed by Apple Inc A digital audio player, more commonly referred to as an MP3 player, is a Consumer electronics device that stores organizes and plays audio files Some

Desktop

A KDE 4 desktop. KDE 4 is the current series of releases of the K Desktop Environment.

A GNOME 2. A gnome is a Mythical creature characterized by its extremely small size and subterranean lifestyle 20 desktop.

Main article: Desktop Linux

Although there is a lack of Linux ports for some Mac OS X and Microsoft Windows programs in domains such as desktop publishing^[29] and professional audio,^[30][31][32] applications roughly equivalent to those available for Mac and Windows are available for Linux. Desktop Linux, also called Linux on the desktop, refers to specialized Linux distributions with features designed for desktop Personal computer users Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. Desktop publishing (also known as DTP) combines a Personal computer and WYSIWYG page layout Software to create Publication Documents Professional audio, also 'pro audio' can be used a term to refer to both a type of audio equipment as well as a type of audio engineering application ^[33]

Most Linux distributions provide a program for browsing a list of thousands of free software applications that have already been tested and configured for a specific distribution. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified

Many free software titles that are popular on Windows, such as Pidgin, Mozilla Firefox, Openoffice.org, and GIMP, are available for Linux. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Pidgin (formerly named Gaim) is a multi-platform Instant messaging client. OpenOfficeorg ( OOo or OOo) is a free Cross-platform office application suite available for a number of different computer The GNU Image Manipulation Program, or GIMP, is a free Raster graphics editor used to process digital graphics and photographs A growing amount of proprietary desktop software is also supported under Linux,^[34] examples being Adobe Flash Player, Acrobat Reader, Matlab, Nero Burning ROM, Opera, Google Picasa, RealPlayer, and Skype. The Adobe Flash Player is a widely distributed proprietary multimedia and application player created by Macromedia and now developed and distributed by Adobe Adobe Acrobat is a family of computer programs developed by Adobe Systems, designed to view create manipulate and manage files in Adobe's Portable Document MATLAB is a numerical computing environment and Programming language. Nero Burning ROM, commonly called just Nero, is a popular optical disc authoring program for Microsoft Windows and Linux by Nero AG Opera is a Web browser and Internet suite developed by the Opera Software company Picasa is a Software application for organizing and editing digital photos originally created by Idealab and now owned by Google. RealPlayer (briefly known also as RealOne Player) is a proprietary Cross-platform media player by RealNetworks that plays a number Skype (skaɪp is Software that allows users to make telephone calls over the Internet. In the field of animation and visual effects, most high end software, such as AutoDesk Maya, Softimage XSI and Apple Shake, is available for Linux, Windows and/or Mac OS X. Maya is a high-end 3D computer graphics and 3D modeling software package originally developed by Alias Systems Corporation, but now owned by Shake is an image Compositing package used in the post-production industry CrossOver is a proprietary solution based on the open source Wine project that supports running older Windows versions of Microsoft Office and Adobe Photoshop versions through CS2. CrossOver (known before version 60 as CrossOver Office) is the collective name for three commercial and proprietary programs developed by CodeWeavers Wine is a free Software application which aims to allow Unix-like computer Operating systems on the X86 architecture to execute Microsoft Office is a set of interrelated desktop applications servers and services collectively referred to as an Office suite, for the Microsoft Windows and Microsoft Office 2007 and Adobe Photoshop CS3 are known not to work. Microsoft Office 2007 (officially called 2007 Microsoft Office system) is the most recent Windows version of the Microsoft Office system, Microsoft's ^[35][36]

Besides the free Windows compatibility layer Wine, most distributions offer Dual boot and X86 virtualization for running both Linux and Windows on the same computer. Wine is a free Software application which aims to allow Unix-like computer Operating systems on the X86 architecture to execute Multi boot or Multi booting (usually dual booting, but many OSes can be booted from the same computer is the act of installing multiple Operating x86 virtualization is the method by which X86 -based "guest" operating systems are run under another "host" x86 operating system with little or no modification

Linux's open nature allows distributed teams to localize Linux distributions for use in locales where localizing proprietary systems would not be cost-effective. In Computing, Internationalization and localization (also spelled internationalisation and localisation, see spelling differences) are means of adapting For example the Sinhalese language version of the Knoppix distribution was available for a long time before Microsoft Windows XP was translated to Sinhalese. Sinhalese or Sinhala (සිංහල ISO 15919: siṁhala ˈsiŋhələ earlier referred to as Singhalese) is the language of the Sinhalese Knoppix, or KNOPPIX (nopɪks is a GNU/Linux Operating system based on Debian designed to be run directly from a CD / DVD Windows XP is a family of 32-bit and 64-bit Operating systems produced by Microsoft for use on Personal computers including home and In this case the Lanka Linux User Group played a major part in developing the localized system by combining the knowledge of university professors, linguists, and local developers.

The performance of Linux on the desktop has been a controversial topic, with at least one key Linux kernel developer, Con Kolivas, accusing the Linux community of favouring performance on servers. He quit Linux development because he was frustrated with this lack of focus on the desktop, and then gave a 'tell all' interview on the topic. ^[37]

See also: Linux gaming

Servers and supercomputers

Historically, Linux has mainly been used as a server operating system, and has risen to prominence in that area; Netcraft reported in February 2008 that five of the ten most reliable internet hosting companies run Linux on their web servers. Linux gaming refers to playing or developing video games for Linux Operating A server is a Computer dedicated to providing one or more services over a computer network typically through a request-response routine Netcraft is an Internet services company based in Bath, England. The term web server can mean one of two things A Computer program that is responsible for accepting HTTP requests from web clients which are ^[38] This is due to its relative stability and long uptime, and the fact that desktop software with a graphical user interface for servers 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. The Acronym LAMP refers to a Solution stack of software usually Free and open source software, used to run dynamic Web sites or servers MySQL is a Relational database management system (RDBMS which has more than 11 million installations NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below PHP is a computer Scripting language. Originally designed for producing Dynamic web pages it has evolved to include a Command line interface capability Python is a general-purpose High-level programming language. Its design philosophy emphasizes programmer productivity and code readability

Linux is commonly used as an operating system for supercomputers. A supercomputer is a Computer that is at the frontline of processing capacity particularly speed of calculation (at the time of its introduction As of November 2007, out of the top 500 systems, 426 (85. November 2007 is the eleventh month of that year It began on a Thursday and 30 days later ended on a Friday 2%) run Linux. ^[39]

Embedded devices

See also: Embedded Linux and Linux devices

Due to its low cost and ability to be easily modified, an embedded Linux is often used in embedded systems. Embedded Linux is the use of a Linux Operating system in Embedded computer systems such as Mobile phones Personal digital assistants Linux based devices or Linux devices are Computer appliances that are powered by Linux Operating system. Embedded Linux is the use of a Linux Operating system in Embedded computer systems such as Mobile phones Personal digital assistants An embedded system is a special-purpose Computer system designed to perform one or a few dedicated functions often with Real-time computing constraints

• Mobile phones or PDAs running on Linux and built on open source platform became a trend from 2007, like the Nokia N810's Internet Tablet OS, Openmoko's Neo1973 and the on-going Google Android. The Nokia N810 Internet Tablet is an Internet appliance from Nokia, announced on October 17 2007 at the Web 2 Openmoko is a project which encompasses two related sub-projects with the combined aim of creating a family of Open source Mobile phones The project was founded Android is a software platform and Operating system for Mobile devices based on the Linux Kernel, developed by Google

16. 7% of smartphones sold worldwide during 2006 were using Linux^[40]

• The popular TiVo digital video recorder uses a customized version of Linux. A smartphone is a Mobile phone offering advanced capabilities beyond a typical mobile phone often with PC -like functionality TiVo (pronounced ˈtiːvoʊ is a brand of Digital video recorder (DVR in the United States, Canada, and Australia created by TiVo ^[41]

• Several network firewall and router standalone products, including several from Linksys, use Linux internally, using its advanced firewall and routing capabilities. A firewall is an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system A router ('rautər in the USA 'rutər in the UK and Ireland, or either pronunciation in Australia and Canada is a Computer whose software and hardware are usually Linksys, founded in 1988 and acquired by Cisco Systems in 2003, is the leader in sales of home and small office network products

Market share and uptake

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. This article covers adoption of the Linux Operating system by homes organizations companies and governments ^[42] 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. ^[43]

IDC's report for Q1 2007 says that Linux now holds 12. International Data Corporation ( IDC) is a Market research and analysis firm specializing in Information technology, Telecommunications and consumer 7% of the overall server market. ^[44] This estimate was based on the number of Linux servers sold by various companies.

Desktop adoption of Linux is approximately 1%. In comparison, Microsoft operating systems hold more than 90%. The following is a list of Microsoft operating systems. For the Codenames that Microsoft gave their Operating systems see Microsoft codenames. ^{[45][46][47][48][49][50][51]}

Proponents and analysts attribute the relative success of Linux to its security, reliability,^[52] low cost, and freedom from vendor lock-in. In Economics, vendor lock-in, also known as proprietary lock-in, or customer lock-in, makes a customer dependent on a vendor for products ^[53]

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. Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. That is changing however with the rise of virtualization technology (e. g VMWare, VirtualBox as well as hardware support by Intel and AMD), and recently Google has begun to fund Wine, which acts as a compatibility layer, allowing users to run some Windows programs directly under Linux. VMware Inc ( is a Software developer and a global leader in the Virtualization market VirtualBox is an X86 virtualization software package originally created by German software company innotek now developed by Sun Microsystems as part Wine is a free Software application which aims to allow Unix-like computer Operating systems on the X86 architecture to execute

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. The XO-1, previously known as the $100 Laptop or Children's Machine, is an inexpensive Laptop computer intended to be distributed to children in developing 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 among the major supporters of the project. Google Inc is an American public corporation, earning revenue from advertising related to its Internet search, e-mail, online In Computing, Red Hat Inc ( is a company dedicated to Free and open source software, and a major Linux distribution vendor eBay Inc is an American Internet company that manages eBaycom an Online auction and shopping Website in which people and businesses buy and ^[54] While the XO will also have a Windows option, it will be primarilly deployed using RHEL. Red Hat Enterprise Linux is a Linux distribution produced by Red Hat and targeted toward the commercial market including mainframes.

See also: Usage share of desktop operating systems

Code size

A 2001 study of Red Hat Linux 7. This is a list of collections of statistics showing the usage share of the most popular desktop and notebook Operating systems The information is derived from web browser user agent 1 found that this distribution contained 30 million source lines of code. Source lines of code ( SLOC) is a Software metric used to measure the size of a software program by counting the number of lines in the text of the program's Using the Constructive Cost Model, the study estimated that this distribution required about eight thousand man-years of development time. The CO nstructive CO st MO del (COCOMO is an algorithmic Software Cost Estimation Model developed by Barry Boehm. According to the study, if all this software had been developed by conventional proprietary means, it would have cost about 1. Proprietary software is Computer software on which the producer has set restrictions on use private modification copying, or republishing. 08 billion dollars (year 2000 U. S. dollars) to develop in the United States. ^[55]

Most of the code (71%) was written in the C programming language, but many other languages were used, including C++, assembly language, Perl, Python, Fortran, and various shell scripting languages. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured A programming language is an Artificial language that can be used to write programs which control the behavior of a machine particularly a Computer. C++ (" C Plus Plus " ˌsiːˌplʌsˈplʌs is a general-purpose Programming language. See the terminology section below for information regarding inconsistent use of the terms assembly and assembler NOTES FOR EDITORS "Perl" is not an acronym (read the "Name" section below Python is a general-purpose High-level programming language. Its design philosophy emphasizes programmer productivity and code readability Fortran (previously FORTRAN) is a general-purpose, procedural, imperative Programming language that is especially suited to A shell script is a script written for the shell, or Command line interpreter, of an Operating system. 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. ^[55]

In a later study, the same analysis was performed for Debian GNU/Linux version 4. 0. ^[56] This distribution contained over 283 million source lines of code, and the study estimated that it would have cost 5. 4 billion euros ($6. 85 billion USD) to develop using proprietary methods. The United States dollar ( sign: $; code: USD) is the unit of Currency of the United States; it has also been

Licensing, trademark, and naming

The Linux kernel and most GNU software are licensed under the GNU General Public License (GPL). A software license (or software licence in commonwealth usage is a Legal instrument governing the usage or redistribution of copyright protected software 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. ”^[57] 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. The GNU Lesser General Public License (formerly the GNU Library General Public License) or LGPL is a Free software license published by the Free Software The MIT License is a Free software license originating at the Massachusetts Institute of Technology (MIT used by the MIT X Consortium.

Torvalds has publicly stated that he would not move the Linux kernel (currently licensed under GPL version 2) to version 3 of the GPL, released in mid-2007, specifically citing some provisions in the new license which prohibit the use of the software in digital rights management. Digital rights management ( DRM) is a generic term that refers to Access control technologies used by hardware manufacturers publishers and Copyright holders ^[58][59]

In the United States, the name Linux is a trademark registered to Linus Torvalds. A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual ^[60] Initially, nobody registered it, but on August 15, 1994, William R. Events 778 - The Battle of Roncevaux Pass, at which Roland is killed Year 1994 ( MCMXCIV) was a Common year starting on Saturday (link will display full 1994 Gregorian calendar) 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. ^[61] The licensing of the trademark has since been handled by the Linux Mark Institute. The Linux Mark Institute ( LMI) is an organization which administers the " Linux " Trademark on behalf of Linus Torvalds for 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. Trademarks were traditionally protected in the United States only under State Common law, growing out of the Tort of Unfair competition. 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. ^[62]

See also: SCO-Linux controversies

GNU/Linux

Main article: 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. The SCO-Linux controversies are a series of legal and public disputes between the Software company SCO Group (SCO and various Linux vendors and users The GNU/Linux naming controversy is a dispute among members of the Free and open source software community. The Free Software Foundation ( FSF) is a Non-profit corporation founded by Richard Stallman on 4 October 1985 to support the Free software movement GNU variants is a term used by the Free Software Foundation and others to refer to Operating systems which use Application software and system libraries ^[63] 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, the term's use outside of the enthusiast community is limited. Debian ( pronounced) is a computer Operating system composed entirely of Free and open source software. Debian ( pronounced) is a computer Operating system composed entirely of Free and open source software. 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.

See also

• Linux software
• Comparison of Linux distributions
• Comparison of Windows and Linux
• Comparison of open source and closed source
• Linux Foundation
• List of Linux devices
• List of Linux distributions
• Linux Documentation Project
• Hardware certification
• Linux Standard Base
• Plan 9 from Bell Labs
• Security-Enhanced Linux
• The Cathedral and the Bazaar
• Virtual PC > Emulating Linux-based environments

References

External links

• Linux kernel website and archives
• GNU Project website
• The Linux Mark Institute (manages the Linux trade mark)
• The Linux Foundation
• The Linux Documentation Project
• Google Linux Search
• Intro to Linux at HowStuffWorks
• Center for learning (LPI certification)