Precursors , principal author of the Linux kernel The
Unix operating system was conceived of and implemented in 1969, at
AT&T's
Bell Labs in the United States, by
Ken Thompson,
Dennis Ritchie,
Douglas McIlroy, and
Joe Ossanna. First released in 1971, Unix was written entirely in
assembly language, as was common practice at the time. In 1973, in a key pioneering approach, it was rewritten in the
C programming language by Dennis Ritchie (except for some hardware and I/O routines). The availability of a
high-level language implementation of Unix made its
porting to different computer platforms easier. As a 1956
antitrust case forbade AT&T from entering the computer business, AT&T provided the operating system's
source code to anyone who asked. As a result, Unix use grew quickly and it became widely adopted by
academic institutions and businesses. In 1984,
AT&T divested itself of its
regional operating companies, and was released from its obligation not to enter the computer business; freed of that obligation, Bell Labs began selling Unix as a
proprietary product, where users were not legally allowed to modify it.
Onyx Systems began selling early microcomputer-based Unix workstations in 1980. Later,
Sun Microsystems, founded as a spin-off of a student project at
Stanford University, also began selling Unix-based desktop workstations in 1982. While Sun workstations did not use commodity PC hardware, for which Linux was later originally developed, it represented the first successful commercial attempt at distributing a primarily single-user microcomputer that ran a Unix operating system. With Unix increasingly "locked in" as a proprietary product, the
GNU Project, started in 1983 by
Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed entirely of
free software. Work began in 1984. Later, in 1985, Stallman started the
Free Software Foundation and wrote the
GNU General Public License (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries,
compilers,
text editors, a
command-line shell, and a
windowing system) were completed, although low-level elements such as
device drivers,
daemons, and the
kernel, called
GNU Hurd, were stalled and incomplete.
Minix was created by
Andrew S. Tanenbaum, a
computer science professor, and released in 1987 as a minimal Unix-like operating system targeted at students and others who wanted to learn operating system principles. Although the
complete source code of Minix was freely available, the licensing terms prevented it from being
free software until the licensing changed in April 2000.
Creation While attending the
University of Helsinki in the fall of 1990, Torvalds enrolled in a Unix course. The course used a
MicroVAX minicomputer running
Ultrix, and one of the required texts was
Operating Systems: Design and Implementation by
Andrew S. Tanenbaum. This textbook included a copy of Tanenbaum's
Minix operating system. It was with this course that Torvalds first became exposed to Unix. In 1991, he became curious about operating systems. Frustrated by the licensing of Minix, which at the time limited it to educational use only, After not finding the POSIX documentation, Torvalds initially resorted to determining system calls from
SunOS documentation owned by the university for use in operating its
Sun Microsystems server. He also learned some system calls from Tanenbaum's Minix text. Torvalds began the development of the Linux kernel on Minix and applications written for Minix were also used on Linux. Later, Linux matured and further Linux kernel development took place on Linux systems. GNU applications also replaced all Minix components, because it was advantageous to use the freely available code from the GNU Project with the fledgling operating system; code licensed under the GNU GPL can be reused in other computer programs as long as they also are released under the same or a compatible license. Torvalds initiated a switch from his original license, which prohibited commercial redistribution, to the GNU GPL. Developers worked to integrate GNU components with the Linux kernel, creating a fully functional and free operating system. Although not released until 1992, due to
legal complications, the development of
386BSD, from which
NetBSD,
OpenBSD and
FreeBSD descended, predated that of Linux. Linus Torvalds has stated that if the
GNU kernel or 386BSD had been available in 1991, he probably would not have created Linux.
Copyright, trademark, and naming is sometimes stylized with incorporation of the
GNU logoThe Linux kernel is
licensed under the GNU General Public License (GPL), version 2. The GPL requires that anyone who distributes software based on source code under this license must make the originating source code (and any modifications) available to the recipient under the same terms. Other key components of a typical Linux distribution are also mainly licensed under the GPL, but they may use other licenses; many libraries use the
GNU Lesser General Public License (LGPL), a more permissive variant of the GPL, and the
X.Org implementation of the X Window System uses the
MIT License. Torvalds states that the Linux kernel will not move from version 2 of the GPL to version 3. He specifically dislikes some provisions in the new license which prohibit the use of the software in
digital rights management. It would also be impractical to obtain permission from all the copyright holders, who number in the thousands. A 2001 study of
Red Hat Linux 7.1 found that this distribution contained 30 million
lines of source code. Most of the source code (71%) was written in the C programming language, but many other languages were used, including
C++,
Lisp, assembly language, Perl, Python,
Fortran, and various
shell scripting languages. 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. This distribution contained close to 283 million lines of source code, and the study estimated that it would have required about seventy three thousand man-years and cost (in dollars) to develop by conventional means. s holding a very early version of Linux In the United States, the name
Linux is a trademark registered to Linus Torvalds. The licensing of the trademark has since been handled by the
Linux Mark Institute (LMI). Torvalds has stated that he trademarked the name only to prevent someone else from using it. LMI originally charged a nominal sublicensing fee for use of the Linux name as part of trademarks, but later changed this in favor of offering a free, perpetual worldwide sublicense. The Free Software Foundation (FSF) prefers
GNU/Linux as the name when referring to the operating system as a whole, because it considers Linux distributions to be
variants of the GNU operating system initiated in 1983 by
Richard Stallman, president of the FSF. also use
GNU/Linux when referring to the operating system as a whole. Most media and common usage, however, refers to this family of operating systems simply as
Linux, as do many large Linux distributions (for example,
SUSE Linux and
Red Hat Enterprise Linux). , about 8% to 13% of the
lines of code of the Linux distribution Ubuntu (version "Natty") is made of GNU components (the range depending on whether GNOME is considered part of GNU); meanwhile, 6% is taken by the Linux kernel, increased to 9% when including its direct dependencies.
Naming Linus Torvalds had wanted to call his invention "Freax", a
portmanteau of "free", "freak", and "x" (as an allusion to Unix). During the start of his work on the system, some of the project's
makefiles included the name "Freax" for about half a year. Torvalds considered the name "Linux" but dismissed it as too egotistical. To facilitate development, the files were uploaded to the
FTP server of
FUNET in September 1991. Ari Lemmke, Torvalds' coworker at the
Helsinki University of Technology (HUT) who was one of the volunteer administrators for the FTP server at the time, did not think that "Freax" was a good name, so he named the project "Linux" on the server without consulting Torvalds. However, in this recording, he pronounces Linux as '''' () with a short but
close front unrounded vowel, instead of a
near-close near-front unrounded vowel as in his newsgroup post.
Commercial and popular uptake The adoption of Linux in production environments, rather than being used only by hobbyists, started to take off first in the mid-1990s in the supercomputing community, where organizations such as
NASA started replacing their increasingly expensive machines with
clusters of inexpensive commodity computers running Linux. Commercial use began when
Dell and
IBM, followed by
Hewlett-Packard, started offering Linux support to escape
Microsoft's monopoly in the desktop operating system market. Today, Linux systems are used throughout computing, from
embedded systems to virtually all
supercomputers, and have secured a place in server installations such as the popular
LAMP application stack. The use of Linux distributions in home and enterprise desktops has been growing. Linux distributions have also become popular in the
netbook market, with many devices shipping with customized Linux distributions installed, and Google releasing their own
ChromeOS designed for netbooks. Linux's greatest success in the consumer market is perhaps the mobile device market, with Android being the dominant operating system on
smartphones and very popular on
tablets and, more recently, on
wearables, and vehicles.
Linux gaming is also on the rise with
Valve showing its support for Linux and rolling out
SteamOS, its own gaming-oriented Linux distribution, which was later implemented in their
Steam Deck platform. Linux distributions have also gained popularity with various local and national governments, such as the federal government of
Brazil.
Development Linus Torvalds is the lead maintainer for the Linux kernel and guides its development, while
Greg Kroah-Hartman is the lead maintainer for the stable branch.
Zoë Kooyman is the executive director of 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. == Usage ==