GNU is a Unix-like computer operating system developed by the GNU Project.
It is composed wholly of free software.
It is based on the GNU Hurd kernel and is intended to be a "complete Unix-compatible
software system" GNU is a recursive acronym for "GNU's Not Unix!", chosen because GNU's
design is Unix-like, but differs from Unix by being free software and containing no Unix
code.
Development of GNU was initiated by Richard Stallman in 1983 and was the original focus
of the Free Software Foundation, but no stable release of GNU yet exists as of January 2014.
However, non-GNU kernels, most famously the Linux kernel, can also be used with GNU software.
Stallman views GNU as a "technical means to a social end."
History
The plan for the GNU operating system was publicly announced on September 27, 1983,
on the net.unix-wizards and net.usoft newsgroups by Richard Stallman.
Software development began on January 5, 1984, when Stallman quit his job at the Massachusetts
Institute of Technology Artificial Intelligence Laboratory so that they could not claim ownership
or interfere with distributing GNU as free software.
Richard Stallman chose the name by using various plays on words, including the song The Gnu.
The goal was to bring a wholly free software operating system into existence.
Stallman wanted computer users to be "free", as most were in the 1960s and 1970s – free
to study the source code of the software they use, free to share the software with other
people, free to modify the behavior of the software, and free to publish their modified
versions of the software.
This philosophy was later published as the GNU Manifesto in March 1985.
Richard Stallman's experience with the Incompatible Timesharing System, an early operating system
written in assembly language that became obsolete due to discontinuation of PDP-10, the computer
architecture for which ITS was written, led to a decision that a portable system was necessary.
It was thus decided that GNU would be mostly 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, and the Mach microkernel that forms the basis of the GNU Mach core of GNU Hurd.
With the exception of the aforementioned third-party components, most of GNU has been written by
volunteers of the GNU Project; 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.
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 C library,
and GNU Core Utilities, but also the GNU Debugger, GNU Binary Utilities, the bash shell and the
GNOME desktop environment.
GNU developers have contributed Linux ports of GNU applications and utilities, which are
now also widely used on other operating systems such as BSD variants, Solaris and Mac OS X.
Many GNU programs have been ported to other operating systems, including proprietary platforms
such as Microsoft Windows and Mac OS X.
Compared to their proprietary Unix counterparts, GNU programs have also been shown to be more
reliable.
As of August 2014, there are a total of 452 GNU packages hosted on the official GNU development
site.
GNU variants
The official kernel of GNU Project is the GNU Hurd microkernel; however, as of 2012,
the Linux kernel is officially part of the GNU Project in the form of Linux-libre, a
variant of Linux with all proprietary components removed.
Other kernels like the FreeBSD kernel also work together with GNU software to form a
working operating system.
The FSF maintains that Linux, when used with GNU tools and utilities, should be considered
a variant of GNU, and promotes the term GNU/Linux for such systems.
The GNU Project has endorsed variants using the Linux kernel, such as gNewSense, Trisquel
and Parabola GNU/Linux-libre.
Other GNU variants which do not use the Hurd as a kernel include Nexenta Core and GNU-Darwin.
Debian GNU/kFreeBSD and Debian GNU/NetBSD from Debian bring the early plan of GNU on
a BSD kernel full circle.
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.
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, the copyright
holder in this case enforces it rather than the Free Software Foundation.
For the software developed under the GNU Project, Stallman wrote a license called the GNU 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 and a program called UniPress,
over a controversy around software code use in the GNU Emacs 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 GNU General Public License.
This license is now used by most GNU programs, as well as a large number of free software
programs that are not part of the GNU Project; it is also the most commonly used free software
license.
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.
In 1991, the GNU Lesser General Public License, then known as the Library General Public License,
was written for the GNU C Library 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, for documentation, followed in 2000.
The GPL and LGPL were revised to version 3 in 2007, adding clauses to protect users against
hardware restrictions that prevent user to run modified software on their own devices.
In addition to GNU's own packages, the GNU Project's licenses are also used by many unrelated
projects, such as the Linux kernel, which is often used with GNU software.
A minority of the software used by GNU, such as the X Window System, is licensed under
permissive free software licenses.
Logo
The logo for GNU is a gnu 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.
See also
References
External links Official website
Ports of GNU utilities for Microsoft Windows The daemon, the GNU and the penguin