GNU 〔 is an extensive collection of computer software that can be used to build a Unix-like operating system. GNU is composed wholly of free software.〔
''GNU'' is a recursive acronym for ''"GNU's Not Unix!"'',〔〔(【引用サイトリンク】title=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.
The GNU project includes an operating system kernel, GNU HURD, which was the original focus of the Free Software Foundation (FSF).
〔Vaughan-Nichols, Steven J. "(Opinion: The top 10 operating system stinkers )", ''Computerworld'', 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."〕
〔Lessig, Lawrence. ''The Future of Ideas: The Fate of the Commons in a Connected World'', p. 54. Random House, 2001. ISBN 978-0-375-50578-2. About Stallman: "He had mixed all of the ingredients needed for an operating system to function, but he was missing the core."〕
However, non-GNU kernels, most famously the Linux kernel, can also be used with GNU software; and since the kernel is the least mature part of GNU, this is how it is usually used. The combination of GNU software and the Linux kernel is commonly known as Linux (or less frequently GNU/Linux; see GNU/Linux naming controversy).
GNU is still missing some components to make it a full operating system that a person can readily install and use on a computer. In practice, most usable GNU-based operating systems are Linux distributions. They contain the Linux kernel, GNU components and software from many other free software projects.
Richard Stallman, the founder of the project, views GNU as a "technical means to a social end."〔.〕
== History ==
Development of the GNU operating system was initiated by Richard Stallman at the Massachusetts Institute of Technology (MIT) Artificial Intelligence Laboratory as a project called the GNU Project which 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 Lab so that they could not claim ownership or interfere with distributing GNU components 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 (ITS),〔 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 the development would be started using C and Lisp as system programming languages,〔(【引用サイトリンク】title=Timeline of GNU/Linux and Unix )〕 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,〔 and the Mach microkernel that forms the basis of the GNU Mach core of GNU Hurd (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 (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.〔(Red Hat buys software firm, shuffles CEO - CNET News )〕
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