GNU () is an extensive collection of

free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, ...

(383 packages as of January 2022), which can be used as an operating system or can be used in parts with other operating systems. The use of the completed GNU tools led to the family of operating systems popularly known as

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

. Most of GNU is licensed under the

GNU Project The GNU Project () is a free software, mass collaboration project announced by Richard Stallman on September 27, 1983. Its goal is to give computer users freedom and control in their use of their computers and Computer hardware, computing devi ...

's own General Public License ( GPL). Richard Stallman - Fête de l'Humanité 2014 - 010

GNU is also the project within which the free software concept originated.

Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement activist and programmer. He campaigns for software to be distributed in such a manner that its users have the freedom to u ...

, the founder of the project, views GNU as a "technical means to a social end". Relatedly,

Lawrence Lessig Lester Lawrence Lessig III (born June 3, 1961) is an American academic, attorney, and political activist. He is the Roy L. Furman Professor of Law at Harvard Law School and the former director of the Edmond J. Safra Center for Ethics at Harvard ...

states in his introduction to the second edition of Stallman's book '' Free Software, Free Society'' that in it Stallman has written about "the social aspects of software and how Free Software can create community and social justice".

Name

''GNU'' is a

recursive acronym A recursive acronym is an acronym that refers to itself, and appears most frequently in computer programming. The term was first used in print in 1979 in Douglas Hofstadter's book '' Gödel, Escher, Bach: An Eternal Golden Braid'', in which Hof ...

for "GNU's Not Unix!", chosen because GNU's design is

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

, but differs from

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

by being free software and containing no Unix code. Stallman chose the name by using various plays on words, including the song ''

The Gnu "The Gnu" (sometimes known as "A Gnu", "I'm a Gnu" or "The Gnu Song") is a humorous song about a talking gnu by Flanders and Swann. The word ''gnu'' is consistently pronounced in the song with two syllables as "g-noo", with the ''g'' clearly ...

''.

History

Development of the GNU operating system was initiated by

while he worked at

MIT Artificial Intelligence Laboratory Computer Science and Artificial Intelligence Laboratory (CSAIL) is a research institute at the Massachusetts Institute of Technology (MIT) formed by the 2003 merger of the Laboratory for Computer Science (LCS) and the Artificial Intelligence La ...

. It was called the GNU Project, and was publicly announced on September 27, 1983, on the net.unix-wizards and net.usoft

newsgroup A Usenet newsgroup is a repository usually within the Usenet system, for messages posted from users in different locations using the Internet. They are discussion groups and are not devoted to publishing news. Newsgroups are technically distin ...

s by Stallman. Software development began on January 5, 1984, when Stallman quit his job at the Lab so that they could not claim ownership or interfere with distributing GNU components as free software. The goal was to bring a completely free software operating system into existence. Stallman wanted computer users to be free to study the source code of the software they use, share software with other people, modify the behavior of software, and publish their modified versions of the software. This philosophy was published as the

GNU Manifesto __NOTOC__ The ''GNU Manifesto'' is a call-to-action by Richard Stallman encouraging participation and support of the GNU Project's goal in developing the GNU free computer operating system. The GNU Manifesto was published in March 1985 in '' Dr ...

in March 1985. Richard Stallman's experience with the

Incompatible Timesharing System Incompatible Timesharing System (ITS) is a time-sharing operating system developed principally by the MIT Artificial Intelligence Laboratory, with help from Project MAC. The name is the jocular complement of the MIT Compatible Time-Sharing Syste ...

(ITS), an early operating system written in assembly language that became obsolete due to discontinuation of

PDP-10 Digital Equipment Corporation (DEC)'s PDP-10, later marketed as the DECsystem-10, is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, especi ...

, the computer architecture for which ITS was written, led to a decision that a

portable Portable may refer to: General * Portable building, a manufactured structure that is built off site and moved in upon completion of site and utility work * Portable classroom, a temporary building installed on the grounds of a school to provide a ...

system was necessary. It was thus decided that the development would be started using C and

Lisp A lisp is a speech impairment in which a person misarticulates sibilants (, , , , , , , ). These misarticulations often result in unclear speech. Types * A frontal lisp occurs when the tongue is placed anterior to the target. Interdental lispi ...

as system programming languages, and that GNU would be compatible with Unix. At the time, Unix was already a popular proprietary operating system. The design of Unix was modular, so it could be reimplemented piece by piece. Much of the needed software had to be written from scratch, but existing compatible third-party free software components were also used such as the TeX typesetting system, the

X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting ...

, and the

Mach Mach may refer to Mach number, the speed of sound in local conditions. It may also refer to: Computing * Mach (kernel), an operating systems kernel technology * ATI Mach, a 2D GPU chip by ATI * GNU Mach, the microkernel upon which GNU Hurd is bas ...

microkernel that forms the basis of the GNU Mach core of

GNU Hurd GNU Hurd is a collection of microkernel servers written as part of GNU, for the GNU Mach microkernel. It has been under development since 1990 by the GNU Project of the Free Software Foundation, designed as a replacement for the Unix kernel, ...

(the official kernel of GNU). With the exception of the aforementioned third-party components, most of GNU has been written by volunteers; some in their spare time, some paid by companies, educational institutions, and other non-profit organizations. In October 1985, Stallman set up the

Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, with the organization's preference for software being distributed under copyleft ("s ...

(FSF). In the late 1980s and 1990s, the FSF hired software developers to write the software needed for GNU. As GNU gained prominence, interested businesses began contributing to development or selling GNU software and technical support. The most prominent and successful of these was Cygnus Solutions, now part of Red Hat.

Components

The system's basic components include the

GNU Compiler Collection The GNU Compiler Collection (GCC) is an optimizing compiler produced by the GNU Project supporting various programming languages, hardware architectures and operating systems. The Free Software Foundation (FSF) distributes GCC as free sof ...

(GCC), the

GNU C library The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++ (and, indirectly, other programming languages). It was started in the 1980s by ...

(glibc), and

GNU Core Utilities The GNU Core Utilities or coreutils is a package of GNU software containing implementations for many of the basic tools, such as cat, ls, and rm, which are used on Unix-like operating systems. In September 2002, the ''GNU coreutils'' were cr ...

(coreutils), but also the

GNU Debugger The GNU Debugger (GDB) is a portable debugger that runs on many Unix-like systems and works for many programming languages, including Ada, C, C++, Objective-C, Free Pascal, Fortran, Go, and partially others. History GDB was first writte ...

(GDB), GNU Binary Utilities (binutils), the GNU Bash shell. GNU developers have contributed to Linux

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as ...

s of GNU applications and utilities, which are now also widely used on other operating systems such as

BSD The Berkeley Software Distribution or Berkeley Standard Distribution (BSD) is a discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Be ...

variants, Solaris and

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

. Many GNU programs have been ported to other operating systems, including proprietary platforms such as Microsoft Windows and macOS. GNU programs have been shown to be more reliable than their proprietary Unix counterparts. As of January 2022, there are a total of 459 GNU packages (including decommissioned, 383 excluding) hosted on the official GNU development site.

GNU as an operating system

In its original meaning, and one still common in hardware engineering, the operating system is a basic set of functions to control the hardware and manage things like task scheduling and

system call In computing, a system call (commonly abbreviated to syscall) is the programmatic way in which a computer program requests a service from the operating system on which it is executed. This may include hardware-related services (for example, acc ...

s. In modern terminology used by software developers, the collection of these functions is usually referred to as a

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine lea ...

, while an 'operating system' is expected to have a more extensive set of programmes. The GNU project maintains two kernels itself, allowing the creation of pure GNU operating systems, but the GNU toolchain is also used with non-GNU kernels. Due to the two different definitions of the term 'operating system', there is an ongoing debate concerning the naming of distributions of GNU packages with a non-GNU kernel. (See below.)

With kernels maintained by GNU and FSF

GNU Hurd

The original kernel of GNU Project is the

microkernel, which was the original focus of the

(FSF).Vaughan-Nichols, Steven J.
Opinion: The top 10 operating system stinkers
, ''

Computerworld ''Computerworld'' (abbreviated as CW) is an ongoing decades old professional publication which in 2014 "went digital." Its audience is information technology (IT) and business technology professionals, and is available via a publication website ...

'', April 9, 2009: "... after more than 25 years in development, GNU remains incomplete: its kernel, Hurd, has never really made it out of the starting blocks. ... Almost no one has actually been able to use the OS; it's really more a set of ideas than an operating system." With the April 30, 2015 release of the Debian GNU/Hurd 2015 distro, GNU now provides all required components to assemble an operating system that users can install and use on a computer. However, the Hurd kernel is not yet considered production-ready but rather a base for further development and non-critical application usage.

Linux-libre

As of 2012, a fork of the

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ...

became officially part of the GNU Project in the form of

Linux-libre Linux-libre is a modified version of the Linux kernel that contains no binary blobs, obfuscated code, or code released under proprietary licenses. In the Linux kernel, they are mostly used for proprietary firmware images. While generally re ...

, a variant of Linux with all proprietary components removed. The GNU Project has endorsed Linux-libre distributions, such as

gNewSense gNewSense was a Linux distribution, active from 2006 to 2016. It was based on Debian, and developed with sponsorship from the Free Software Foundation. Its goal was user-friendliness, but with all proprietary (e.g. binary blobs) and non-free ...

, Trisquel and Parabola GNU/Linux-libre.

With non-GNU kernels

Because of the development status of Hurd, GNU is usually paired with other kernels such as

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

. Whether the combination of GNU libraries with external kernels is a GNU operating system with a kernel (e.g. GNU with Linux), because the GNU collection renders the kernel into a usable operating system as understood in modern software development, or whether the kernel is an operating system unto itself with a GNU layer on top (i.e. Linux with GNU), because the kernel can operate a machine without GNU, is a matter of ongoing debate. The FSF maintains that an operating system built using the

and GNU tools and utilities should be considered a variant of GNU, and promotes the term ''GNU/Linux'' for such systems (leading to the

GNU/Linux naming controversy Within the free software and the open-source software communities there is controversy over whether to refer to computer operating systems that use a combination of GNU software and the Linux kernel as "GNU/Linux" or "Linux" systems. Proponents ...

). This view is not exclusive to the FSF. Notably,

Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of De ...

, one of the biggest and oldest Linux distributions, refers to itself as ''Debian GNU/Linux''.

Copyright, GNU licenses, and stewardship

The GNU Project recommends that contributors assign the copyright for GNU packages to the Free Software Foundation, though the Free Software Foundation considers it acceptable to release small changes to an existing project to the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

. However, this is not required; package maintainers may retain copyright to the GNU packages they maintain, though since only the copyright holder may enforce the license used (such as the GNU GPL), the copyright holder in this case enforces it rather than the Free Software Foundation. For the development of needed software, Stallman wrote a license called the

GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end user In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ulti ...

(first called Emacs General Public License), with the goal to guarantee users freedom to share and change free software. Stallman wrote this license after his experience with

James Gosling James Gosling (born May 19, 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java programming language. Gosling was elected a member of the National Academy of Engineering in 2004 for the conception ...

and a program called UniPress, over a controversy around software code use in the

GNU Emacs GNU Emacs is a free software text editor. It was created by GNU Project founder Richard Stallman, based on the Emacs editor developed for Unix operating systems. GNU Emacs has been a central component of the GNU project and a flagship proje ...

program. For most of the 80s, each GNU package had its own license: the Emacs General Public License, the GCC General Public License, etc. In 1989, FSF published a single license they could use for all their software, and which could be used by non-GNU projects: the

(GPL). This license is now used by most of GNU software, as well as a large number of free software programs that are not part of the GNU Project; it also historically has been the most commonly used

free software license A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and software distribution, redistribute that software. These actions are usually prohibited by copyright law, but the rights-holde ...

(though recently challenged by the

MIT license The MIT License is a permissive free software license originating at the Massachusetts Institute of Technology (MIT) in the late 1980s. As a permissive license, it puts only very limited restriction on reuse and has, therefore, high license co ...

). It gives all recipients of a program the right to run, copy, modify and distribute it, while forbidding them from imposing further restrictions on any copies they distribute. This idea is often referred to as

copyleft Copyleft is the legal technique of granting certain freedoms over copies of copyrighted works with the requirement that the same rights be preserved in derivative works. In this sense, ''freedoms'' refers to the use of the work for any purpose, ...

. In 1991, the

GNU Lesser General Public License The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

(LGPL), then known as the Library General Public License, was written for the

GNU C Library The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++ (and, indirectly, other programming languages). It was started in the 1980s by ...

to allow it to be linked with proprietary software. 1991 also saw the release of version 2 of the GNU GPL. The

GNU Free Documentation License The GNU Free Documentation License (GNU FDL or simply GFDL) is a copyleft license for free documentation, designed by the Free Software Foundation (FSF) for the GNU Project. It is similar to the GNU General Public License, giving readers the r ...

(FDL), for documentation, followed in 2000. The GPL and LGPL were revised to version 3 in 2007, adding clauses to protect users against

hardware restrictions A hardware restriction (sometimes called hardware DRM) is low-level protection enforced by electronic components. The hardware restriction scheme may protect against physical or malware attacks or complement a digital rights management system imp ...

that prevent users from running modified software on their own devices. Besides GNU's packages, the GNU Project's licenses are used by many unrelated projects, such as the

, often used with GNU software. A minority of the software used by most of

Linux distributions A Linux distribution (often abbreviated as distro) is an operating system made from a software collection that includes the Linux kernel and, often, a package management system. Linux users usually obtain their operating system by downloading on ...

, such as the X Window System, is licensed under

permissive free software license A permissive software license, sometimes also called BSD-like or BSD-style license, is a free-software license which instead of copyleft protections, carries only minimal restrictions on how the software can be used, modified, and redistributed, ...

Logo

The logo for GNU is a

gnu GNU () is an extensive collection of free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any ...

head. Originally drawn by Etienne Suvasa, a bolder and simpler version designed by Aurelio Heckert is now preferred. It appears in GNU software and in printed and electronic documentation for the GNU Project, and is also used in Free Software Foundation materials. There was also a modified version of the official logo. It was created by the

in September 2013 in order to commemorate the 30th anniversary of the

References

External links

*
Ports of GNU utilities for Microsoft Windows

The daemon, the GNU and the penguin
{{Authority control Free software operating systems GNU Project GNU Project software Mach (kernel) Microkernel-based operating systems Unix variants Acronyms