View source for Software:Linux

{{Short description|Family of Unix-like operating systems}}
{{Infobox OS
| name = Linux (no automatically included version) <!-- this "hack" unties the infobox from the separate template that lists latest Linux kernel versions – this article is about Linux and not about the Linux kernel so listing kernel versions introduces confusion -->
| title = Linux
| logo = Tux.svg
| logo_size = 150px
| logo caption = [[Tux (mascot)|Tux]] the penguin, the mascot of Linux<ref name="LinuxOnLine2008">{{cite web | url = http://www.linux.org/info/logos.html | title = Linux Logos and Mascots |access-date=August 11, 2009 | last = Linux Online | year = 2008 | archive-url = https://web.archive.org/web/20100815085106/http://www.linux.org/info/logos.html | archive-date = August 15, 2010 }}</ref>
| logo_alt = Tux the penguin
| developer = Community contributors, <br /> Linus Torvalds
| programmed in = [[C (programming language)|C]], [[Assembly language|assembly language]]s, and others
| family = [[Unix-like]]
| working state = Current
| source model = [[Open-source software|Open source]]
| released = {{start date and age|1991|9|17}}
| latest release version = <!-- The kernel version is displayed on the "Linux kernel" article; please don't insert it here, as this article covers Linux kernel + userland combos. -->
| latest release date = 
| latest preview version = <!-- The kernel version is displayed on the "Linux kernel" article; please don't insert it here, as this article covers Linux kernel + userland combos. -->
| latest preview date = 
| repo = {{URL|https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/}}
| marketing target = [[Cloud computing]], embedded devices, [[Mainframe computer|mainframe computer]]s, [[Engineering:Mobile device|mobile device]]s, [[Engineering:Personal computer|personal computer]]s, [[Server (computing)|servers]], [[Supercomputer|supercomputer]]s
| language = Multilingual
| updatemodel = 
| supported platforms = [[DEC Alpha|Alpha]], [[ARC (processor)|ARC]], [[ARM architecture|ARM]], [[Engineering:M·CORE|C-Sky]], [[Qualcomm Hexagon|Hexagon]], [[Company:Loongson|LoongArch]], m68k, Microblaze, [[MIPS architecture|MIPS]], Nios II, [[Engineering:OpenRISC|OpenRISC]], [[PA-RISC]], [[PowerPC]], [[Engineering:RISC-V|RISC-V]], s390, [[Engineering:SuperH|SuperH]], [[SPARC]], [[X86|x86]], Xtensa <!-- Please do not include 64-bit extensions of 32-bit ISAs, e.g. sparc64, ppc64, x86-64, etc. -->
| kernel type = [[Monolithic kernel|Monolithic]]
| userland = [[Software:GNU|GNU]],{{Efn|GNU is the primary userland used in nearly all Linux distributions.<ref>{{cite web |url=http://www.linux.org/threads/gnu-userland.7429/ |title=GNU Userland |archive-url=https://web.archive.org/web/20160308205852/http://www.linux.org/threads/gnu-userland.7429/ |archive-date=March 8, 2016}}</ref><ref>{{cite web |url=http://cyborginstitute.org/projects/administration/unix-fundamentals/ |title=Unix Fundamentals — System Administration for Cyborgs |archive-url=https://web.archive.org/web/20161005114243/http://cyborginstitute.org/projects/administration/unix-fundamentals/ |archive-date=October 5, 2016}}</ref><ref>{{cite web|url=http://openbookproject.net/courses/intro2ict/system/os_intro.html|title=Operating Systems — Introduction to Information and Communication Technology|url-status=live|archive-url=https://web.archive.org/web/20160221222415/http://openbookproject.net/courses/intro2ict/system/os_intro.html|archive-date=February 21, 2016}}</ref> The GNU userland contains system daemons, user applications, the GUI, and various libraries. GNU Core utilities are an essential part of most distributions. Most Linux distributions use the [[Software:X Window System|X Window]] system.<ref>{{cite web|url=http://www.tldp.org/FAQ/Linux-FAQ/x-windows.html|title=The X Window System|url-status=live|archive-url=https://web.archive.org/web/20160120234827/http://tldp.org/FAQ/Linux-FAQ/x-windows.html|archive-date=January 20, 2016}}</ref> Other components of the userland, such as the [[Widget toolkit|widget toolkit]], vary with the specific distribution, desktop environment, and user configuration.<ref>{{cite web|url=http://pclosmag.com/html/issues/201109/page08.html|title=PCLinuxOS Magazine – HTML|url-status=dead|archive-url=https://web.archive.org/web/20130515020543/http://pclosmag.com/html/Issues/201109/page08.html|archive-date=May 15, 2013}}</ref>}} [[Software:BusyBox|BusyBox]]{{Efn|BusyBox is an alternative userland used in many embedded Linux distributions. BusyBox replaces most GNU Core utilities.<ref>{{cite web|url=https://busybox.net/about.html|title=The Busybox about page|website=busybox.net|access-date=November 30, 2021|archive-date=November 27, 2021|archive-url=https://web.archive.org/web/20211127134347/https://busybox.net/about.html|url-status=live}}</ref> One notable Desktop distribution using BusyBox is [[Software:Alpine Linux|Alpine Linux]].<ref>{{cite web|url=https://alpinelinux.org/about/|title=The Alpine Linux about page|website=alpinelinux.org|access-date=November 30, 2021|archive-date=May 8, 2011|archive-url=https://web.archive.org/web/20110508001131/https://alpinelinux.org/about/|url-status=live}}</ref>}}
| ui = {{ubl|[[Unix shell]] ([[Command-line interface|CLI]])|Most [[Software:Linux distribution|distributions]] include a [[Software:Desktop environment|desktop environment]] (GUI).}}
| license = [[Software:GPLv2|GPLv2]]<ref>{{cite web |url=https://www.kernel.org/category/faq.html |title=The Linux Kernel Archives: Frequently asked questions |website=kernel.org |date=September 2, 2014 |access-date=September 4, 2015 |url-status=live |archive-url=https://web.archive.org/web/20150905100143/https://www.kernel.org/category/faq.html |archive-date=September 5, 2015}}</ref>{{Efn|The name "Linux" itself is a trademark owned by Linus Torvalds<ref name="US_trademark">{{cite web |url = http://assignments.uspto.gov/assignments/q?db=tm&rno=1916230 |title = U.S. Reg No: 1916230 |publisher = United States Patent and Trademark Office |access-date = April 1, 2006 |url-status=live |archive-url = https://web.archive.org/web/20130624203325/http://assignments.uspto.gov/assignments/q?db=tm&rno=1916230 |archive-date = June 24, 2013 |df = mdy-all }}</ref> and administered by the [[Organization:Linux Mark Institute|Linux Mark Institute]].}}
| other_articles = [[Software:Linux kernel|Linux kernel]] <br /> [[Software:Linux distribution|Linux distribution]]
}}<!-- Based on long-standing consensus, please do not change this to read that GNU/Linux is the correct name for Linux distributions incorporating GNU software; the change will be reverted. This has been extensively discussed. Please see MOS:LINUX for more information. -->

'''Linux''' ({{IPAc-en||ˈ|l|ɪ|n|ʊ|k|s}} {{respell|LIN|uuks}})<ref name="pronunciation-2">{{ cite newsgroup |newsgroup= comp.os.linux | title = Re: How to pronounce ''Linux''? |message-id= 1992Apr23.123216.22024@klaava.Helsinki.FI | date = April 23, 1992 |access-date=January 9, 2007 | url=https://groups.google.com/d/msg/comp.os.linux/L_TTOib3_08/yOG2vLtsp1MJ}}</ref> is a family of [[Free and open-source software|open-source]] [[Unix-like]] [[Operating system|operating system]]s based on the [[Software:Linux kernel|Linux kernel]],<ref>{{ cite book | last = Eckert | first = Jason W. | year = 2012 | title = Linux+ Guide to Linux Certification | edition = Third | publisher = Cengage Learning | place = Boston, Massachusetts | page = 33 | isbn = 978-1111541538 | url = https://books.google.com/books?id=EHLH4S78LmsC&pg=PA33 | access-date = April 14, 2013 | quote = The shared commonality of the kernel is what defines a system's membership in the Linux family; the differing [[Open-source software|OSS]] applications that can interact with the common kernel are what differentiate Linux distributions. | url-status=live | archive-url = https://web.archive.org/web/20130509031220/http://books.google.com/books?id=EHLH4S78LmsC&pg=PA33 | archive-date = May 9, 2013 | df = mdy-all }}</ref> an [[Software:Kernel (operating system)|operating system kernel]] first released on September 17, 1991, by Linus Torvalds.<ref>{{cite web | title = Twenty Years of Linux according to Linus Torvalds | url = http://www.zdnet.com/article/twenty-years-of-linux-according-to-linus-torvalds/ | publisher = ZDNet | date = April 13, 2011 | access-date = September 19, 2016 | url-status=live | archive-url = https://web.archive.org/web/20160919232940/http://www.zdnet.com/article/twenty-years-of-linux-according-to-linus-torvalds/ | archive-date = September 19, 2016 | df = mdy-all }}</ref><ref>{{cite newsgroup | title = Free minix-like kernel sources for 386-AT | author = Linus Benedict Torvalds | date = October 5, 1991 | newsgroup = comp.os.minix | url = https://groups.google.com/group/comp.os.minix/msg/2194d253268b0a1b?pli=1 | access-date = September 30, 2011 | archive-date = March 2, 2013 | archive-url = https://web.archive.org/web/20130302010902/http://groups.google.com/group/comp.os.minix/msg/2194d253268b0a1b?pli=1 | url-status = live }}</ref><ref>{{cite web | title = What Is Linux: An Overview of the Linux Operating System | url = https://medium.com/@theinfovalley097/what-is-linux-an-overview-of-the-linux-operating-system-77bc7421c7e5?sk=b80b38575284317290c86e56001e43b1 | publisher = Medium | access-date = December 21, 2019 | df = mdy-all | archive-date = June 12, 2020 | archive-url = https://web.archive.org/web/20200612030853/https://medium.com/@theinfovalley097/what-is-linux-an-overview-of-the-linux-operating-system-77bc7421c7e5?sk=b80b38575284317290c86e56001e43b1 | url-status = live }}</ref> Linux is typically [[Package manager|packaged]] as a [[Software:Linux distribution|Linux distribution]] (distro), which includes the kernel and supporting [[Software:System software|system software]] and [[Library (computing)|libraries]], many of which are provided by the [[GNU Project]]. Many Linux distributions use the word "Linux" in their name, but the [[Organization:Free Software Foundation|Free Software Foundation]] uses and recommends the name "'''GNU/Linux'''" to emphasize the use and importance of [[Software:GNU|GNU]] software in many distributions, causing some controversy.<ref name="gnu_linux_faq" /><ref name="linux-and-gnu">{{cite web | url = https://www.gnu.org/gnu/linux-and-gnu.html | title = Linux and the GNU System | publisher = Gnu.org | access-date = September 1, 2013 | url-status=live | archive-url = https://web.archive.org/web/20170319145123/http://www.gnu.org/gnu/linux-and-gnu.html | archive-date = March 19, 2017 | df = mdy-all }}</ref>

Popular Linux distributions<ref>{{cite web|url=http://distrowatch.com/dwres.php?resource=major |title=DistroWatch.com: Put the fun back into computing. Use Linux, BSD. |last=DistroWatch |website=distrowatch.com |access-date=2016-12-30 |url-status=dead |archive-url=https://web.archive.org/web/20130402195650/http://distrowatch.com/dwres.php?resource=major |archive-date=April 2, 2013 }}</ref><ref>{{Cite news|url=https://www.linux.com/news/best-linux-distros-2016/|title=Best Linux distros of 2016: Something for everyone|last=himanshu|first=Swapnil|newspaper=CIO|access-date=2022-02-01|url-status=live|archive-url=https://web.archive.org/web/20161231170119/http://www.cio.com/article/3023349/linux/best-linux-distros-of-2016-something-for-everyone.html|archive-date=December 31, 2016}}</ref><ref>{{cite web|url=http://www.tecmint.com/top-best-linux-distributions-2016/|title=10 Top Most Popular Linux Distributions of 2016|website=www.tecmint.com|access-date=2016-12-30|url-status=live|archive-url=https://web.archive.org/web/20161230141717/http://www.tecmint.com/top-best-linux-distributions-2016/|archive-date=December 30, 2016}}</ref> include [[Software:Debian|Debian]], [[Software:Fedora Linux|Fedora Linux]], [[Software:Arch Linux|Arch Linux]], and [[Software:Ubuntu|Ubuntu]]. Commercial distributions include [[Software:Red Hat Enterprise Linux|Red Hat Enterprise Linux]] and [[Software:SUSE Linux Enterprise|SUSE Linux Enterprise]]. Desktop Linux distributions include a windowing system such as [[Software:X Window System|X11]] or [[Software:Wayland (protocol)|Wayland]] and a [[Software:Desktop environment|desktop environment]] such as [[Software:GNOME|GNOME]] or [[Software:KDE Plasma 5|KDE Plasma]]. Distributions intended for [[Server (computing)|servers]] may not have a [[Graphical user interface|graphical user interface]] at all, or include a [[Solution stack|solution stack]] such as [[Software:LAMP (software bundle)|LAMP]]. Because Linux is freely redistributable, anyone may create a distribution for any purpose.<ref name="what">{{Cite web|title=What is Linux?|url=https://opensource.com/resources/linux|website=Opensource.com|language=en|access-date=2020-05-12|archive-date=May 13, 2020|archive-url=https://web.archive.org/web/20200513110848/https://opensource.com/resources/linux|url-status=live}}</ref>

Linux was originally developed for [[Engineering:Personal computer|personal computer]]s based on the Intel x86 architecture, but has since been [[Porting|ported]] to more platforms than any other operating system.<ref>{{cite news |author=Barry Levine |title=Linux' {{sic|22|th|nolink=yes}} Birthday Is Commemorated - Subtly - by Creator |url=http://www.cmswire.com/cms/information-management/linux-22th-birthday-is-commemorated-subtly-by-creator-022244.php |access-date=May 10, 2015 |publisher=Simpler Media Group, Inc |date=August 26, 2013 |quote="Originally developed for Intel x86-based PCs, Torvalds' "hobby" has now been released for more hardware platforms than any other OS in history." |url-status=live |archive-url=https://web.archive.org/web/20150518155152/http://www.cmswire.com/cms/information-management/linux-22th-birthday-is-commemorated-subtly-by-creator-022244.php |archive-date=May 18, 2015}}</ref> Because of the dominance of Linux-based [[Software:Android (operating system)|Android]] on [[Engineering:Smartphone|smartphone]]s, Linux, including Android, has the [[Software:Usage share of operating systems|largest]] installed base of all general-purpose operating systems {{as of|2022|5|lc=y}}.<ref>{{Cite web|url=https://gs.statcounter.com/os-market-share|title=Operating System Market Share Worldwide|website=StatCounter Global Stats|access-date=October 18, 2020|archive-date=February 15, 2020|archive-url=https://web.archive.org/web/20200215213114/https://gs.statcounter.com/os-market-share|url-status=live}}</ref><ref>{{cite web|last=McPherson|first=Amanda|date=December 13, 2012|title=What a Year for Linux: Please Join us in Celebration|url=http://www.linuxfoundation.org/news-media/blogs/browse/2012/12/what-year-linux-please-join-us-celebration|url-status=dead|archive-url=https://web.archive.org/web/20140417232521/http://www.linuxfoundation.org/news-media/blogs/browse/2012/12/what-year-linux-please-join-us-celebration|archive-date=April 17, 2014|access-date=April 16, 2014|publisher=Linux Foundation}}</ref><ref>{{cite web|url=http://www.linuxfordevices.com/c/a/News/Trolltech-rolls-complete-Linux-smartphone-stack/ |title=Trolltech rolls "complete" Linux smartphone stack |access-date=January 12, 2017 |last=Linux Devices |date=November 28, 2006 |archive-url=https://archive.today/20120525231448/http://www.linuxfordevices.com/c/a/News/Trolltech-rolls-complete-Linux-smartphone-stack/ |archive-date=May 25, 2012 |url-status=dead }}</ref> Although Linux is, {{as of|2022|11|lc=y}}, used by only around 2.6 percent of [[Engineering:Desktop computer|desktop computer]]s,<ref name="statcounter-desktop">{{cite web|url=https://gs.statcounter.com/os-market-share/desktop/|title=Desktop Operating System Market Share Worldwide|website=StatCounter Global Stats|access-date=June 30, 2022|archive-date=August 20, 2022|archive-url=https://web.archive.org/web/20220820033759/https://gs.statcounter.com/os-market-share/desktop|url-status=live}}</ref> the [[Engineering:Chromebook|Chromebook]], which runs the Linux kernel-based [[Software:ChromeOS|ChromeOS]], dominates the US [[Social:K–12|K–12]] education market and represents nearly 20 percent of sub-$300 [[Engineering:Laptop|notebook]] sales in the US.<ref>{{cite web|url=http://www.zdnet.com/article/chromebook-shipments-leap-by-67-percent/|title=Chromebook shipments leap by 67 percent|author=Steven J. Vaughan-Nichols|work=ZDNet|access-date=September 29, 2015|url-status=live|archive-url=https://web.archive.org/web/20150929055809/http://www.zdnet.com/article/chromebook-shipments-leap-by-67-percent/|archive-date=September 29, 2015}}</ref> Linux is the leading operating system on servers (over 96.4% of the top one million web servers' operating systems are Linux),<ref>{{cite web|title=OS Market Share and Usage Trends|url=http://www.w3cook.com/os/summary/|website=W3Cook.com|archive-url=https://web.archive.org/web/20150806093859/http://www.w3cook.com/os/summary|archive-date=6 August 2015}}</ref> leads other big iron systems such as [[Mainframe computer|mainframe computer]]s, and is used on all of the [[TOP500|world's 500 fastest supercomputers]]{{Efn|As measured by the [[TOP500]] list, which uses [[Software:LINPACK benchmarks#HPL|HPL]] to measure computational power}} ({{as of|November 2017|lc=true}}, having gradually displaced all competitors).<ref>{{cite web |url=https://www.zdnet.com/article/linux-totally-dominates-supercomputers/ |title=Linux totally dominates supercomputers |last=Vaughan-Nichols |first=Steven J. |year=2017 |publisher=ZDNet |publication-date=November 14, 2017 |archive-url=https://web.archive.org/web/20171114211600/http://www.zdnet.com/article/linux-totally-dominates-supercomputers/ |archive-date=November 14, 2017 |access-date=October 25, 2018}}</ref><ref>{{cite web |url=https://www.computerworld.com/article/2521639/ibm-s-newest-mainframe-is-all-linux.html |title=IBM's newest mainframe is all Linux |last=Thibodeau |first=Patrick |year=2009 |publisher=Computerworld |publication-date=December 9, 2009 |archive-url=https://web.archive.org/web/20161111053745/http://www.computerworld.com/article/2521639/computer-hardware/ibm-s-newest-mainframe-is-all-linux.html |archive-date=November 11, 2016 |access-date=February 22, 2009}}</ref><ref name="rules_supercomputers">{{cite news | title = Linux rules supercomputers | url = https://www.forbes.com/2005/03/15/cz_dl_0315linux.html | last = Lyons | first = Daniel | access-date = February 22, 2007 | work = Forbes | date = March 15, 2005 | url-status=live | archive-url = https://web.archive.org/web/20070224235804/http://www.forbes.com/home/enterprisetech/2005/03/15/cz_dl_0315linux.html | archive-date = February 24, 2007 | df = mdy-all }}</ref>

Linux also runs on [[Embedded system|embedded system]]s, i.e., devices whose operating system is typically built into the [[Firmware|firmware]] and is highly tailored to the system. This includes [[Engineering:Router (computing)|routers]], [[Engineering:Automation|automation]] controls, [[Engineering:Smart home technology|smart home devices]], [[Engineering:Video game console|video game console]]s,<ref name="LinuxDevices">{{cite web |last=[[Company:IBM|IBM]] |date=October 2001 |title=Linux Watch (WatchPad) |url=http://researcher.watson.ibm.com/researcher/view_group.php?id=6101 |url-status=live |archive-url=https://web.archive.org/web/20150618153004/http://researcher.watson.ibm.com/researcher/view_group.php?id=6101 |archive-date=June 18, 2015 |access-date=June 18, 2015 |df=mdy-all}}</ref> [[Engineering:Television|television]]s (Samsung and LG [[Engineering:Smart TV|Smart TV]]s),<ref name="Linux Smart TVs">{{cite web | title = Linux continues advance in smart TV market | url = http://linuxgizmos.com/linux-continues-advance-in-smart-tv-market/ | website = linuxgizmos.com | author = Eric Brown | date = Mar 29, 2019 | access-date = May 15, 2020 | archive-date = June 29, 2020 | archive-url = https://web.archive.org/web/20200629105311/http://linuxgizmos.com/linux-continues-advance-in-smart-tv-market/ | url-status = live }}</ref><ref>{{cite web | title = Sony Open Source Code Distribution Service | url = http://products.sel.sony.com/opensource/ | publisher = Sony Electronics | access-date = October 8, 2011 | url-status=dead | archive-url = https://web.archive.org/web/20111004171109/http://products.sel.sony.com/opensource/ | archive-date = October 4, 2011 | df = mdy-all }}</ref><ref>{{cite web | title = Sharp Liquid Crystal Television Instruction Manual | url = http://files.sharpusa.com/Downloads/ForHome/HomeEntertainment/LCDTVs/Manuals/Archive/tel_man_LC32_37_42HT3U.pdf | publisher = Sharp Electronics | access-date = October 8, 2011 | page = 24 | url-status = dead | archive-url = https://web.archive.org/web/20120111111044/http://files.sharpusa.com/Downloads/ForHome/HomeEntertainment/LCDTVs/Manuals/Archive/tel_man_LC32_37_42HT3U.pdf | archive-date = January 11, 2012 | df = mdy-all }}</ref> automobiles (Tesla, Audi, Mercedes-Benz, Hyundai, and Toyota),<ref name="Linux cars">{{cite web|title=It's a Linux-powered car world|url=https://www.zdnet.com/article/its-a-linux-powered-car-world/|website=ZDNet|author=Steven J. Vaughan-Nichols|date=January 4, 2019|access-date=May 15, 2020|archive-date=August 3, 2020|archive-url=https://web.archive.org/web/20200803053324/https://www.zdnet.com/article/its-a-linux-powered-car-world/|url-status=live}}</ref> and [[Engineering:Spacecraft|spacecraft]] ([[Engineering:Falcon 9|Falcon 9]] rocket, [[Engineering:SpaceX Dragon 2|Dragon]] crew capsule, and the [[Engineering:Perseverance (rover)|''Perseverance'']] rover).<ref name="auto">{{Cite web|url=https://www.zdnet.com/google-amp/article/from-earth-to-orbit-with-linux-and-spacex/|title=From Earth to orbit with Linux and SpaceX &#124; ZDNet|website=www.zdnet.com|access-date=June 6, 2020|archive-date=August 3, 2020|archive-url=https://web.archive.org/web/20200803060356/https://www.zdnet.com/google-amp/article/from-earth-to-orbit-with-linux-and-spacex/|url-status=live}}</ref><ref>{{Cite web |title=Linux on Mars! |url=https://www.itpro.com/software/linux/360542/linux-on-mars |access-date=2022-06-30 |website=IT PRO |date=August 18, 2021 |language=en |archive-date=May 19, 2022 |archive-url=https://web.archive.org/web/20220519145641/https://www.itpro.com/software/linux/360542/linux-on-mars |url-status=live }}</ref>

Linux is one of the most prominent examples of free and open-source [[Software|software]] collaboration. The [[Source code|source code]] may be used, modified, and distributed commercially or non-commercially by anyone under the terms of its respective licenses, such as the [[Software:GNU General Public License|GNU General Public License]] (GPL). The Linux kernel, for example, is licensed under the GPLv2, with an exception for [[System call|system call]]s that allows code that calls the kernel via system calls not to be licensed under the GPL.<ref>{{cite web|url=https://www.kernel.org/doc/html/v4.18/process/license-rules.html|title=Linux kernel licensing rules|work=Linux kernel documentation|access-date=June 17, 2022|archive-date=September 6, 2022|archive-url=https://web.archive.org/web/20220906145357/https://www.kernel.org/doc/html/v4.18/process/license-rules.html|url-status=live}}</ref><ref>{{GitHub|https://github.com/torvalds/linux/blob/master/LICENSES/exceptions/Linux-syscall-note}}</ref><ref name="what" />{{TOC limit}}

== History ==
{{Main|History of Linux}}

=== Precursors ===
[[File:Linus Torvalds (cropped).jpg|thumb|right|upright|Linus Torvalds, principal author of the Linux kernel ]]

The [[Software:Unix|Unix]] operating system was conceived and implemented in 1969, at AT&T's [[Organization:Bell Labs|Bell Labs]], in the United States by [[Biography:Ken Thompson|Ken Thompson]], [[Biography:Dennis Ritchie|Dennis Ritchie]], Douglas McIlroy, and Joe Ossanna.<ref>{{Citation| title = The UNIX System: The Evolution of the UNIX Time-sharing System| last = Ritchie| first = D.M.| journal = AT&T Bell Laboratories Technical Journal| volume = 63| number = 8| date = October 1984| page = 1577| doi = 10.1002/j.1538-7305.1984.tb00054.x| s2cid = 571269| quote = However, UNIX was born in 1969 ...}}</ref> First released in 1971, Unix was written entirely in [[Assembly language|assembly language]], as was common practice at the time. In 1973, in a key pioneering approach, it was rewritten in the [[C (programming language)|C]] programming language by Dennis Ritchie (with the exception of some hardware and I/O routines). The availability of a high-level language implementation of Unix made its [[Porting|porting]] to different computer platforms easier.<ref>{{cite web|url=https://opensource.com/article/17/9/open-source-licensing|title=Open source licensing: What every technologist should know|last=Meeker|first=Heather|date=September 21, 2017|website=Opensource.com|archive-url=https://web.archive.org/web/20170924185302/https://opensource.com/article/17/9/open-source-licensing|archive-date=September 24, 2017|url-status=live|access-date=September 24, 2017}}</ref>

Due to an earlier antitrust case{{specify|Which case? United States v. AT&T?|date=November 2023}} forbidding it{{specify|Unix or AT&T?|date=November 2023}} from entering the computer business, AT&T licensed the operating system's [[Source code|source code]] as a [[Social:Trade secret|trade secret]] to anyone who asked.{{clarify|Rephrase this sentence|date=November 2023}} As a result, Unix grew quickly and 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 software|proprietary]] product, where users were not legally allowed to modify it.<ref name="Vetter2021">{{cite book | author = Michael Vetter | date = 10 August 2021 | title = Acquisitions and Open Source Software Development | publisher = Springer Nature | page = 13 | isbn = 978-3-658-35084-0 | url = https://books.google.com/books?id=L_Q8EAAAQBAJ | access-date = 5 August 2022 | archive-date = August 5, 2022 | archive-url = https://web.archive.org/web/20220805143225/https://books.google.com/books?id=L_Q8EAAAQBAJ | url-status = live }}</ref><ref name="Tozzi2017">{{cite book | author = Christopher Tozzi | date = 11 August 2017 | title = For Fun and Profit: A History of the Free and Open Source Software Revolution | publisher = MIT Press | page = 52 | isbn = 978-0-262-03647-4 | url = https://books.google.com/books?id=MXosDwAAQBAJ | access-date = 5 August 2022 | archive-date = August 5, 2022 | archive-url = https://web.archive.org/web/20220805143226/https://books.google.com/books?id=MXosDwAAQBAJ | url-status = live }}</ref>

Onyx Systems began selling early microcomputer-based Unix workstations in 1980. Later, [[Company:Sun Microsystems|Sun Microsystems]], founded as a spin-off of a student project at [[Organization:Stanford University|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.<ref>{{cite book |url=https://www.oreilly.com/library/view/the-cathedral/0596001088/ch01.html |title=The Cathedral and the Bazaar |first=S. Raymond |last=Eric |publisher=O'Reilly & Associates, Inc |location=Sebastopol, California |page=12 |isbn=0-596-00108-8 |date=October 1999 |access-date=July 21, 2022 |quote=In 1982, a group of Unix hackers from Stanford and Berkeley founded Sun Microsystems on the belief that Unix running on relatively inexpensive 68000-based hardware would prove a winning combination for a wide variety of applications. They were right, and their vision set the pattern for an entire industry. While still priced out of reach of most individuals, workstations were cheap for corporations and universities; networks of them (one to a user) rapidly replaced the older VAXes and other time-sharing systems |archive-date=July 18, 2022 |archive-url=https://web.archive.org/web/20220718070144/https://www.oreilly.com/library/view/the-cathedral/0596001088/ch01.html |url-status=live }}</ref><ref>{{cite news |url=https://www.latimes.com/archives/la-xpm-1988-01-31-fi-39535-story.html |title=Sun Microsystems Is Blazing a Red-Hot Trail in Computers: $300-Million AT&T; Deal Moves Firm to Set Sights on IBM |first=Carla |last=Lazzareschi |newspaper=Los Angeles Times |date=January 31, 1988 |access-date=July 21, 2022 |archive-date=July 21, 2022 |archive-url=https://web.archive.org/web/20220721100144/https://www.latimes.com/archives/la-xpm-1988-01-31-fi-39535-story.html |url-status=live }}</ref>

With Unix increasingly "locked in" as a proprietary product, the [[GNU Project]], started in 1983 by [[Biography:Richard Stallman|Richard Stallman]], had the goal of creating a "complete Unix-compatible software system" composed entirely of [[Free software|free software]]. Work began in 1984.<ref name="gnu_announce">{{cite web |url=https://www.gnu.org/gnu/initial-announcement.html |title=About the GNU Project – Initial Announcement |publisher=Gnu.org |date=June 23, 2008 |access-date=March 9, 2009 |url-status=live |archive-url=https://web.archive.org/web/20090305002259/http://www.gnu.org/gnu/initial-announcement.html |archive-date=March 5, 2009}}</ref> Later, in 1985, Stallman started the [[Organization:Free Software Foundation|Free Software Foundation]] and wrote the [[Software:GNU General Public License|GNU General Public License]] (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries, [[Compiler|compiler]]s, [[Software:Text editor|text editor]]s, a [[Software:Shell (computing)#Command-line shells|command-line shell]], and a windowing system) were completed, although low-level elements such as [[Device driver|device driver]]s, [[Daemon (computing)|daemons]], and the [[Software:Kernel (operating system)|kernel]], called [[Software:GNU Hurd|GNU Hurd]], were stalled and incomplete.<ref>{{cite web |url=http://thevarguy.com/open-source-application-software-companies/050415/open-source-history-why-did-linux-succeed |title=Open Source History: Why Did Linux Succeed? |author=Christopher Tozzi |date=August 23, 2016 |access-date=August 17, 2017 |url-status=dead |archive-url=https://web.archive.org/web/20170817205211/http://thevarguy.com/open-source-application-software-companies/050415/open-source-history-why-did-linux-succeed |archive-date=August 17, 2017 }}</ref>

[[Software:MINIX|MINIX]] was created by [[Biography:Andrew S. Tanenbaum|Andrew S. Tanenbaum]], a [[Computer science|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|free software]] until the licensing changed in April 2000.<ref name="minix-lic">{{Cite web|url=http://minix1.woodhull.com/faq/mxlicense.html |title=MINIX is now available under the BSD license |archive-url=https://web.archive.org/web/20160304083114/http://minix1.woodhull.com/faq/mxlicense.html |archive-date=March 4, 2016 |url-status=live |date=April 9, 2000 |website=minix1.woodhull.com}}</ref>

Although not released until 1992, due to legal complications, development of [[Software:386BSD|386BSD]], from which [[Software:NetBSD|NetBSD]], [[Organization:OpenBSD|OpenBSD]] and [[Software:FreeBSD|FreeBSD]] descended, predated that of Linux. Linus Torvalds has stated on separate occasions that if the GNU kernel or 386BSD had been available at the time (1991), he probably would not have created Linux.<ref>{{cite web |url=http://www.dina.dk/~abraham/Linus_vs_Tanenbaum.html |title=Linus vs. Tanenbaum debate |archive-url=https://web.archive.org/web/20121003060514/http://www.dina.dk/~abraham/Linus_vs_Tanenbaum.html |archive-date=October 3, 2012 |access-date=February 19, 2014}}</ref><ref name="meta">{{cite web|url=http://gondwanaland.com/meta/history/interview.html|title=The Choice of a GNU Generation – An Interview With Linus Torvalds|last=Linksvayer|first=Mike|year=1993|work=Meta magazine|access-date=January 20, 2009|url-status=live|archive-url=https://web.archive.org/web/20090225212557/http://gondwanaland.com/meta/history/interview.html|archive-date=February 25, 2009}}</ref>

=== Creation ===
While attending the University of Helsinki in the fall of 1990, Torvalds enrolled in a Unix course.<ref>{{cite web |url=https://www.wired.com/1997/08/linux-5 |title=The Greatest OS That (N)ever Was |first=Glyn |last=Moody |publisher=Wired |date=August 1, 1997 |access-date=July 20, 2022 |archive-date=July 25, 2022 |archive-url=https://web.archive.org/web/20220725204746/http://www.wired.com/1997/08/linux-5/ |url-status=live }}</ref> The course used a [[Engineering:MicroVAX|MicroVAX]] minicomputer running [[Software:Ultrix|Ultrix]], and one of the required texts was ''Operating Systems: Design and Implementation'' by [[Biography:Andrew S. Tanenbaum|Andrew S. Tanenbaum]]. This textbook included a copy of Tanenbaum's [[Software:MINIX|MINIX]] operating system. It was with this course that Torvalds first became exposed to Unix. In 1991, he became curious about operating systems.<ref>{{cite newsgroup | title = What would you like to see most in minix? | newsgroup = comp.os.minix | message-id = 1991Aug25.205708.9541@klaava.Helsinki.FI | url = https://groups.google.com/group/comp.os.minix/msg/b813d52cbc5a044b | last = Torvalds | first = Linus | access-date = September 9, 2006 | archive-date = May 9, 2013 | archive-url = https://web.archive.org/web/20130509134305/http://groups.google.com/group/comp.os.minix/msg/b813d52cbc5a044b | url-status = live }}</ref> Frustrated by the licensing of MINIX, which at the time limited it to educational use only,<ref name="minix-lic" /> he began to work on his own operating system kernel, which eventually became the Linux kernel.

On July 3, 1991, in an effort to implement Unix [[System call|system call]]s, Linus Torvalds attempted unsuccessfully to obtain a digital copy of the [[POSIX]] standards [[Software documentation|documentation]] with a request to the ''comp.os.minix'' newsgroup.<ref>{{cite book |last1=Torvalds |first1=Linus |last2=Diamond |first2=David |date=2001 |title=Just for Fun: The Story of an Accidental Revolutionary |location={{wipe|New York City}} |publisher=HarperCollins |pages=78–80 |isbn=0-06-662073-2}}</ref> After not finding the POSIX documentation, Torvalds initially resorted to determining system calls from [[Software:SunOS|SunOS]] documentation owned by the university for use in operating its [[Company:Sun Microsystems|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.<ref>{{cite newsgroup|title=Chicken and egg: How was the first linux gcc binary created??|author=Linus Torvalds|date=October 14, 1992|newsgroup=comp.os.minix|message-id=1992Oct12.100843.26287@klaava.Helsinki.FI|url=https://groups.google.com/group/comp.os.linux/msg/4ae6db18d3f49b0e|access-date=August 17, 2013|archive-date=May 9, 2013|archive-url=https://web.archive.org/web/20130509140002/http://groups.google.com/group/comp.os.linux/msg/4ae6db18d3f49b0e|url-status=live}}</ref> 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.<ref>{{cite web |url=https://www.kernel.org/pub/linux/kernel/Historic/old-versions/RELNOTES-0.12 |title=Release notes for Linux v0.12 |last=Torvalds |first=Linus |date=January 5, 1992 |publisher=Linux Kernel Archives |archive-url=https://web.archive.org/web/20070819045030/http://www.kernel.org/pub/linux/kernel/Historic/old-versions/RELNOTES-0.12 |archive-date=August 19, 2007 |access-date=July 23, 2007 |quote=The Linux copyright will change: I've had a couple of requests to make it compatible with the GNU copyleft, removing the "you may not distribute it for money" condition. I agree. I propose that the copyright be changed so that it confirms to GNU ─ pending approval of the persons who have helped write code. I assume this is going to be no problem for anybody: If you have grievances ("I wrote that code assuming the copyright would stay the same") mail me. Otherwise, The GNU copyleft takes effect since the first of February. If you do not know the gist of the GNU copyright ─ read it.}}</ref> Developers worked to integrate GNU components with the Linux kernel, creating a fully functional and free operating system.<ref name="gnu history">{{cite web |url=https://www.gnu.org/gnu/gnu-history.html |title=Overview of the GNU System |publisher=Gnu.org |access-date=March 9, 2009 |url-status=live |archive-url=https://web.archive.org/web/20090228140819/http://www.gnu.org/gnu/gnu-history.html |archive-date=February 28, 2009}}</ref>

=== {{Anchor|FREAX}}Naming ===
[[File:Linux 0 12.jpg|thumb|5.25-inch [[Floppy disk|floppy disk]]s holding a very early version of Linux]]

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 [[Makefile|makefile]]s included the name "Freax" for about half a year. Initially, Torvalds considered the name "Linux" but dismissed it as too egotistical.<ref name="fun">Torvalds, Linus and Diamond, David, ''Just for Fun: The Story of an Accidental Revolutionary'', 2001, {{ISBN|0-06-662072-4}}</ref>

To facilitate development, the files were uploaded to the [[File Transfer Protocol|FTP server]] (<code>ftp.funet.fi</code>) of [[Organization:FUNET|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.<ref name="fun" /> Later, however, Torvalds consented to "Linux".

According to a newsgroup post by Torvalds,<ref name="pronunciation-2"/> the word "Linux" should be pronounced ({{IPAc-en|audio=Linus-linux.ogg|ˈ|l|ɪ|n|ʊ|k|s}} {{respell|LIN|uuks}}) with a short 'i' as in 'print' and 'u' as in 'put'. To further demonstrate how the word "Linux" should be pronounced, he included an audio guide with the kernel source code.<ref name="Pronounce">{{cite web|url = https://www.kernel.org/pub/linux/kernel/SillySounds|title = Index of /pub/linux/kernel/SillySounds|access-date = August 3, 2009|last = Torvalds|first = Linus|date = March 1994|url-status=live|archive-url = https://web.archive.org/web/20091008074754/http://www.kernel.org/pub/linux/kernel/SillySounds/|archive-date = October 8, 2009|df = mdy-all}}</ref> However, in this recording, he pronounces Linux as ''{{IPA|/ˈlinʊks/}}'' ({{respell|LEEN|uuks}}) 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 ===
{{Main|Linux adoption}}
[[File:Ubuntu_23.10_Mantic_Minotaur_Desktop_English.png|thumb|Ubuntu, a popular Linux distribution]]
[[File:Nexus 5X (White).jpg|thumb|[[Engineering:Nexus 5X|Nexus 5X]] running Android ]]

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 [[Organization:NASA|NASA]] started to replace their increasingly expensive machines with [[Computer cluster|clusters]] of inexpensive commodity computers running Linux. Commercial use began when [[Company:Dell|Dell]] and [[Company:IBM|IBM]], followed by [[Company:Hewlett-Packard|Hewlett-Packard]], started offering Linux support to escape [[Company:Microsoft|Microsoft]]'s monopoly in the desktop operating system market.<ref name="security">{{cite book |title=Practical UNIX and Internet Security |first1=Simson |last1=Garfinkel |first2=Gene |last2=Spafford |first3=Alan |last3=Schwartz |publisher=O'Reilly |year=2003 |page=21}}</ref>

Today, Linux systems are used throughout computing, from [[Embedded system|embedded system]]s to virtually all [[Supercomputer|supercomputer]]s,<ref name="rules_supercomputers"/><ref>{{cite web |title=Linux system development on an embedded device |url=http://www-128.ibm.com/developerworks/library/l-embdev.html |first1=Anand |last1=Santhanam |author2=Vishal Kulkarni |work=DeveloperWorks |publisher=IBM |date=March 1, 2002 |access-date=July 26, 2007 |archive-url=https://web.archive.org/web/20070329123926/http://www-128.ibm.com/developerworks/library/l-embdev.html |archive-date=March 29, 2007}}</ref> and have secured a place in server installations such as the popular [[Software:LAMP (software bundle)|LAMP]] application stack. Use of Linux distributions in home and enterprise desktops has been growing.<ref name="galli2007">{{cite news | first=Peter | last=Galli | title=Vista Aiding Linux Desktop, Strategist Says | date=August 8, 2007 | publisher=Ziff Davis Enterprise Inc. | url=http://www.eweek.com/c/a/Linux-and-Open-Source/Vista-Aiding-Linux-Desktop-Strategist-Says/ | work=eWEEK | access-date=November 19, 2007 | url-status=live | archive-url=http://arquivo.pt/wayback/20090709050715/http://www.eweek.com/c/a/Linux-and-Open-Source/Vista-Aiding-Linux-Desktop-Strategist-Says/ | archive-date=July 9, 2009 | df=mdy-all }}</ref><ref name="paul2007">{{cite news | first=Ryan | last=Paul | title=Linux market share set to surpass Win 98, OS X still ahead of Vista | date=September 3, 2007 | publisher=Ars Technica, LLC | url=https://arstechnica.com/news.ars/post/20070903-linux-marketshare-set-to-surpass-windows-98.html | work=Ars Technica | access-date=November 19, 2007 | url-status=live | archive-url=https://web.archive.org/web/20071116080339/http://arstechnica.com/news.ars/post/20070903-linux-marketshare-set-to-surpass-windows-98.html | archive-date=November 16, 2007 | df=mdy-all }}</ref><ref name="beer2007">{{cite news|first=Stan |last=Beer |title=Vista to play second fiddle to XP until 2009: Gartner |date=January 23, 2007 |url=http://www.itwire.com.au/content/view/8842/53/ |work=iTWire |access-date=November 19, 2007 |url-status=dead |archive-url=https://web.archive.org/web/20081203204529/http://www.itwire.com.au/content/view/8842/53/ |archive-date=December 3, 2008 }}</ref><ref name="applications2007">{{cite web |url=http://marketshare.hitslink.com/report.aspx?qprid=2&qpmr=15&qpdt=1&qpct=3&qptimeframe=Y |title=Operating System Marketshare for Year 2007 |access-date=November 19, 2007 |date=November 19, 2007 |work=Market Share |publisher=Net Applications |url-status=live |archive-url=https://web.archive.org/web/20130624203258/http://marketshare.hitslink.com/report.aspx?qprid=2&qpmr=15&qpdt=1&qpct=3&qptimeframe=Y |archive-date=June 24, 2013}}</ref><ref name="xitimonitor2007">{{cite news |title=Vista slowly continues its growth; Linux more aggressive than Mac OS during the summer |date=September 24, 2007 |publisher=AT Internet/XiTi.com |url=http://www.xitimonitor.com/en-us/internet-users-equipment/operating-systems-august-2007/index-1-2-7-107.html |work=XiTiMonitor |access-date=November 19, 2007 |archive-url=https://web.archive.org/web/20071214013746/http://www.xitimonitor.com/en-us/internet-users-equipment/operating-systems-august-2007/index-1-2-7-107.html |archive-date=December 14, 2007}}</ref><ref name="globalstats2007">{{cite web |url=http://www.w3counter.com/globalstats.php |title=Global Web Stats |access-date=November 19, 2007 |date=November 10, 2007 |work=W3Counter |publisher=Awio Web Services LLC |url-status=live |archive-url=https://archive.today/20120628/http://www.w3counter.com/globalstats.php |archive-date=June 28, 2012}}</ref><ref name="zeitgeist2004">{{cite web |url=http://www.google.com/press/zeitgeist/zeitgeist-jun04.html |title=June 2004 Zeitgeist |access-date=November 19, 2007 |date=August 12, 2004 |work=Google Press Center |publisher=Google Inc. |url-status=live |archive-url=https://web.archive.org/web/20110711135752/http://www.google.com/press/zeitgeist/zeitgeist-jun04.html |archive-date=July 11, 2011}}</ref> Linux distributions have also become popular in the [[Engineering:Netbook|netbook]] market, with many devices shipping with customized Linux distributions installed, and Google releasing their own [[Software:ChromeOS|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 [[Engineering:Smartphone|smartphone]]s and very popular on [[Engineering:Tablet computer|tablets]] and, more recently, on [[Engineering:Wearable technology|wearables]]. [[Software:Linux gaming|Linux gaming]] is also on the rise with [[Company:Valve Corporation|Valve]] showing its support for Linux and rolling out [[Software:SteamOS|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 {{wipe|Brazil}}.<ref>{{cite web|last1=McMillan|first1=Robert|title=IBM, Brazilian government launch Linux effort|url=http://www.infoworld.com/article/2675550/operating-systems/ibm--brazilian-government-launch-linux-effort.html|website=www.infoworld.com|date=October 10, 2003|publisher=IDG News Service|access-date=February 16, 2015|url-status=live|archive-url=https://web.archive.org/web/20150315055524/http://www.infoworld.com/article/2675550/operating-systems/ibm--brazilian-government-launch-linux-effort.html|archive-date=March 15, 2015}}</ref>

=== Current development ===
[[File:In flight system Linux bootup flat.jpg|thumb|In-flight entertainment system booting up displaying the Linux logo]]
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.<ref>{{cite web |url=https://www.linuxfoundation.org/about/ |title=About Us - The Linux Foundation |access-date=2018-10-01 |archive-date=October 28, 2018 |archive-url=https://web.archive.org/web/20181028015400/https://www.linuxfoundation.org/about/ |url-status=live }}</ref> Zoë Kooyman is the executive director of the Free Software Foundation,<ref>{{Cite web |title=Staff and Board — Free Software Foundation — Working together for free software |url=https://www.fsf.org/about/staff-and-board |archive-url=https://web.archive.org/web/20231121082724/https://www.fsf.org/about/staff-and-board |archive-date=2023-11-21 |access-date=2023-11-22 |website=Free Software Foundation}}</ref> which in turn supports the GNU components.<ref>{{cite web |url=http://www.fsf.org/about/ |title=Free software is a matter of liberty, not price — Free Software Foundation — working together for free software |publisher=Fsf.org |access-date=July 12, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120714122536/http://www.fsf.org/about |archive-date=July 14, 2012 }}</ref> 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.

== Design ==
Many [[Open source|open source]] developers agree that the Linux kernel was not designed but rather [[Biology:Evolution|evolved]] through [[Biology:Natural selection|natural selection]]. Torvalds considers that although the design of Unix served as a scaffolding, "Linux grew with a lot of mutations – and because the mutations were less than random, they were faster and more directed than [[Biology:Mutation#Induced mutation|alpha-particles in DNA]]."<ref>Email correspondence on the Linux Kernel development mailing list {{cite web |author1=Linus Torvalds |title=Re: Coding style, a non-issue |url=https://lwn.net/2001/1206/a/no-design.php3 |website=kernel.org |date=November 30, 2001 |access-date=August 10, 2020 |archive-date=August 12, 2021 |archive-url=https://web.archive.org/web/20210812201159/https://lwn.net/2001/1206/a/no-design.php3 |url-status=live }}</ref> Eric S. Raymond considers Linux's revolutionary aspects to be social, not technical: before Linux, complex software was designed carefully by small groups, but "Linux evolved in a completely different way. From nearly the beginning, it was rather casually hacked on by huge numbers of volunteers coordinating only through the Internet. Quality was maintained not by rigid standards or autocracy but by the naively simple strategy of releasing every week and getting feedback from hundreds of users within days, creating a sort of rapid Darwinian selection on the mutations introduced by developers."<ref>{{cite book |last1=Raymond |first1=Eric S. |editor1-last=O'Reilly |editor1-first=Tim |title=The Cathedral and the Bazaar: Musings on Linux and Open Source by an Accidental Revolutionary |date=2001 |publisher=O'Reilly & Associates |isbn=0-596-00108-8 |page=16 |edition=Second}}</ref> [[Biography:Bryan Cantrill|Bryan Cantrill]], an engineer of a competing OS, agrees that "Linux wasn't designed, it evolved", but considers this to be a limitation, proposing that some features, especially those related to security,<ref>"You have to design it you [[Biology:Fitness landscape|cannot asymptotically reach]] Security." Cantrill 2017</ref> cannot be evolved into, "this is not a biological system at the end of the day, it's a software system."<ref>{{cite AV media |date=November 26, 2015 |url=https://www.youtube.com/watch?v=Ya6h2zKlpaQ |title=The Cantrill Strikes Back {{!}} BSD Now 117 |publisher=Jupiter Broadcasting |via=[[Company:YouTube|YouTube]] |access-date=September 7, 2021 |archive-url=https://web.archive.org/web/20201214063300/https://www.youtube.com/watch?v=Ya6h2zKlpaQ |archive-date=December 14, 2020 |url-status=live}}</ref>

A Linux-based system is a modular Unix-like operating system, deriving much of its basic design from principles established in Unix during the 1970s and 1980s. Such a system uses a [[Monolithic kernel|monolithic kernel]], the Linux kernel, which handles process control, networking, access to the [[Engineering:Peripheral|peripheral]]s, and [[File system|file system]]s. [[Device driver]]s are either integrated directly with the kernel, or added as modules that are loaded while the system is running.<ref>{{cite web | url = https://stackoverflow.com/questions/1806585/why-is-linux-called-a-monolithic-kernel | title = Why is Linux called a monolithic kernel? | year = 2009 | access-date = October 16, 2013 | publisher = stackoverflow.com | url-status=live | archive-url = https://web.archive.org/web/20131017065550/http://stackoverflow.com/questions/1806585/why-is-linux-called-a-monolithic-kernel | archive-date = October 17, 2013 | df = mdy-all }}</ref>

The GNU [[User space and kernel space|userland]] is a key part of most systems based on the Linux kernel, with Android being the notable exception. The [[Software:Glibc|GNU C library]], an implementation of the [[C standard library]], works as a wrapper for the system calls of the Linux kernel necessary to the kernel-userspace interface, the [[Software:GNU toolchain|toolchain]] is a broad collection of programming tools vital to Linux development (including the [[Software:GNU Compiler Collection|compilers]] used to build the Linux kernel itself), and the [[Software:GNU Core Utilities|coreutils]] implement many basic [[Software:List of Unix commands|Unix tools]]. The GNU Project also develops [[Software:Bash (Unix shell)|Bash]], a popular [[Command-line interface|CLI]] shell. The [[Graphical user interface|graphical user interface]] (or GUI) used by most Linux systems is built on top of an implementation of the [[Software:X Window System|X Window System]].<ref name="oreilly-anatomy">{{cite web|url=https://personalpages.manchester.ac.uk/staff/m.dodge/cybergeography/atlas/linux_anatomy.pdf|title=Anatomy of a Linux System|date=July 23–26, 2001|publisher=O'Reilly|access-date=October 10, 2018|archive-date=September 4, 2019|archive-url=https://web.archive.org/web/20190904023052/https://personalpages.manchester.ac.uk/staff/m.dodge/cybergeography/atlas/linux_anatomy.pdf|url-status=live}}</ref> More recently, the Linux community seeks to advance to [[Software:Wayland (protocol)|Wayland]] as the new display server protocol in place of X11. Many other open-source software projects contribute to Linux systems.
{{Linux layers}}

Installed components of a Linux system include the following:<ref name="oreilly-anatomy" /><ref>{{cite web |url=http://www.ibm.com/developerworks/library/l-linuxboot/ |title=Inside the Linux boot process |last=M. Tim Jones |date=May 31, 2006 |publisher=IBM Developer Works |archive-url=https://web.archive.org/web/20131017052010/http://www.ibm.com/developerworks/library/l-linuxboot/ |archive-date=October 17, 2013 |access-date=October 16, 2013}}</ref>
* A [[Software:Bootloader|bootloader]], for example [[Software:GNU GRUB|GNU GRUB]], [[Software:LILO (bootloader)|LILO]], [[Software:SYSLINUX|SYSLINUX]] or [[Software:Systemd-boot|systemd-boot]]. This is a program that loads the Linux kernel into the computer's main memory, by being executed by the computer when it is turned on and after the [[Firmware|firmware]] initialization is performed.
* An [[Software:Init|init]] program, such as the traditional sysvinit and the newer [[Software:Systemd|systemd]], [[Software:OpenRC|OpenRC]] and [[Software:Upstart|Upstart]]. This is the first [[Process (computing)|process]] launched by the Linux kernel, and is at the root of the process tree. It starts processes such as system services and login prompts (whether graphical or in terminal mode).
* [[Library (computing)|Software libraries]], which contain code that can be used by running processes. On Linux systems using [[Executable and Linkable Format|ELF]]-format executable files, the [[Dynamic linker|dynamic linker]] that manages the use of dynamic libraries is known as ld-linux.so. If the system is set up for the user to compile software themselves, header files will also be included to describe the [[API|programming interface]] of installed libraries. Besides the most commonly used software library on Linux systems, the [[Software:GNU C Library|GNU C Library]] (glibc), there are numerous other libraries, such as [[Software:Simple DirectMedia Layer|SDL]] and [[Software:Mesa (computer graphics)|Mesa]].
** The [[C standard library]] is the library necessary to run programs written in [[C (programming language)|C]] on a computer system, with the GNU C Library being the standard. It provides an implementation of the POSIX API, as well as extensions to that API. For embedded systems, alternatives such as [[Software:Musl|musl]], EGLIBC (a glibc fork once used by Debian) and [[Software:UClibc|uClibc]] (which was designed for uClinux) have been developed, although the last two are no longer maintained. Android uses its own C library, [[Software:Bionic|Bionic]]. However, musl can additionally be used as a replacement for glibc on desktop and laptop systems, as seen on certain Linux distributions like [[Software:Void Linux|Void Linux]].
* Basic Unix commands, with GNU coreutils being the standard implementation. Alternatives exist for embedded systems, such as the copyleft [[Software:BusyBox|BusyBox]], and the BSD-licensed [[Software:Toybox|Toybox]].
* [[Widget toolkit]]s are the libraries used to build [[Graphical user interface|graphical user interface]]s (GUIs) for software applications. Numerous widget toolkits are available, including [[Software:GTK|GTK]] and Clutter developed by the GNOME Project, [[Software:Qt|Qt]] developed by the [[Organization:Qt Project|Qt Project]] and led by [[Company:The Qt Company|The Qt Company]], and [[Organization:Enlightenment Foundation Libraries|Enlightenment Foundation Libraries]] (EFL) developed primarily by the [[Software:Enlightenment|Enlightenment]] team.
* A [[Package manager|package management system]], such as [[Software:Dpkg|dpkg]] and [[Software:RPM Package Manager|RPM]]. Alternatively packages can be compiled from binary or source [[Software:Tar (computing)|tarballs]].
* User interface programs such as command shells or windowing environments.

=== User interface ===
The [[User interface|user interface]], also known as the [[Software:Shell (computing)|shell]], is either a command-line interface (CLI), a graphical user interface (GUI), or controls attached to the associated hardware, which is common for embedded systems. For desktop systems, the default user interface is usually graphical, although the CLI is commonly available through [[Terminal emulator|terminal emulator]] windows or on a separate [[Virtual console|virtual console]].

CLI shells are text-based user interfaces, which use text for both input and output. The dominant shell used in Linux is the [[Software:Bash (Unix shell)|Bourne-Again Shell]] (bash), originally developed for the GNU Project. Most low-level Linux components, including various parts of the userland, use the CLI exclusively. The CLI is particularly suited for automation of repetitive or delayed tasks and provides very simple [[Inter-process communication|inter-process communication]].

On desktop systems, the most popular user interfaces are the GUI shells, packaged together with extensive desktop environments, such as [[Software:KDE Plasma 5|KDE Plasma]], [[Software:GNOME|GNOME]], [[Software:MATE|MATE]], [[Software:Cinnamon (desktop environment)|Cinnamon]], [[Software:LXDE|LXDE]], [[Software:Elementary OS|Pantheon]] and [[Software:Xfce|Xfce]], though a variety of additional user interfaces exist. Most popular user interfaces are based on the X Window System, often simply called "X". It provides [[Network transparency|network transparency]] and permits a graphical application running on one system to be displayed on another where a user may interact with the application; however, certain extensions of the X Window System are not capable of working over the network.<ref>{{cite web |url = https://lwn.net/Articles/553415/ |title = The Wayland Situation: Facts About X vs. Wayland (Phoronix) |date = June 8, 2013 |access-date = October 11, 2013 |publisher = LWN.net |author = Jake Edge |url-status=live |archive-url = https://web.archive.org/web/20131022030529/http://lwn.net/Articles/553415/ |archive-date = October 22, 2013 |df = mdy-all }}</ref> Several X display servers exist, with the reference implementation, [[Software:X.Org Server|X.Org Server]], being the most popular.

Server distributions might provide a command-line interface for developers and administrators, but provide a custom interface towards end-users, designed for the use-case of the system. This custom interface is accessed through a client that resides on another system, not necessarily Linux based.

Several types of [[Window manager|window manager]]s exist for X11, including [[Tiling window manager|tiling]], [[Software:Dynamic window manager|dynamic]], [[Software:Stacking window manager|stacking]] and [[Compositing window manager|compositing]]. Window managers provide means to control the placement and appearance of individual application windows, and interact with the X Window System. Simpler [[X window manager]]s such as [[Software:Dwm|dwm]], [[Software:Ratpoison|ratpoison]], or [[Software:I3 (window manager)|i3wm]] provide a [[Minimalism (computing)|minimalist]] functionality, while more elaborate window managers such as [[Software:FVWM|FVWM]], [[Software:Enlightenment|Enlightenment]] or [[Software:Window Maker|Window Maker]] provide more features such as a built-in [[Taskbar|taskbar]] and [[Theme (computing)|themes]], but are still lightweight when compared to desktop environments. Desktop environments include window managers as part of their standard installations, such as [[Software:Mutter|Mutter]] (GNOME), [[Software:KWin|KWin]] (KDE) or [[Software:Xfwm|Xfwm]] (xfce), although users may choose to use a different window manager if preferred.

Wayland is a display server protocol intended as a replacement for the X11 protocol; {{As of|2022|lc=yes}}, it has received relatively wide adoption.<ref>{{Cite web | last=Miller | first=Matthew | url=https://fedoramagazine.org/announcing-fedora-36/ | title=Announcing Fedora 36 | access-date=2022-10-28 | date=May 6, 2022 | archive-date=August 2, 2022 | archive-url=https://web.archive.org/web/20220802155254/https://fedoramagazine.org/announcing-fedora-36/ | url-status=live }}</ref> Unlike X11, Wayland does not need an external window manager and compositing manager. Therefore, a Wayland compositor takes the role of the display server, window manager and compositing manager. Weston is the reference implementation of Wayland, while GNOME's Mutter and KDE's KWin are being ported to Wayland as standalone display servers. Enlightenment has already been successfully ported since version 19.<ref>{{Cite web|last=Diener|first=Derrik|title=What Is Wayland and What Does It Means for Linux Users|url=https://www.maketecheasier.com/what-is-wayland/|access-date=2021-02-14|website=www.maketecheasier.com/|date=December 6, 2016|language=en-US|archive-date=January 27, 2021|archive-url=https://web.archive.org/web/20210127202354/https://www.maketecheasier.com/what-is-wayland/|url-status=live}}</ref>

=== Video input infrastructure ===
{{Main|Software:Video4Linux}}

Linux currently has two modern kernel-userspace APIs for handling video input devices: [[Software:Video4Linux|V4L2]] API for video streams and radio, and [[DVB]] API for digital TV reception.<ref>{{cite web | url = http://linuxtv.org/ | title = Linux TV: Television with Linux | access-date = October 16, 2013 | publisher = linuxtv.org | url-status=live | archive-url = https://web.archive.org/web/20131106185814/http://linuxtv.org/ | archive-date = November 6, 2013 | df = mdy-all }}</ref>

Due to the complexity and diversity of different devices, and due to the large number of formats and standards handled by those APIs, this infrastructure needs to evolve to better fit other devices. Also, a good userspace device library is the key of the success for having userspace applications to be able to work with all formats supported by those devices.<ref>{{cite web | url = https://lwn.net/Articles/203924/ | title = The Video4Linux2 API: an introduction | date = October 11, 2006 | access-date = October 16, 2013 | author = Jonathan Corbet | publisher = LWN.net | url-status=live | archive-url = https://web.archive.org/web/20131007115957/http://lwn.net/Articles/203924/ | archive-date = October 7, 2013 | df = mdy-all }}</ref><ref>{{cite web | url = http://linuxtv.org/downloads/v4l-dvb-apis/compat.html | title = Part I. Video for Linux Two API Specification | work = Chapter 7. Changes | access-date = October 16, 2013 | publisher = linuxtv.org | url-status=dead | archive-url = https://web.archive.org/web/20131017050817/http://linuxtv.org/downloads/v4l-dvb-apis/compat.html | archive-date = October 17, 2013 | df = mdy-all }}</ref>

== Development ==
[[File:Unix timeline.en.svg|thumb|upright=2.25|Simplified history of Unix-like operating systems. Linux shares similar architecture and concepts (as part of the [[POSIX|POSIX]] standard) but does not share non-free source code with the original Unix or MINIX.]]
{{Main|Software:Linux distribution|Free software}}

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 not the only such operating system, although it is by far the most widely used.<ref name="MarketShare09NOV">{{cite web|url = http://marketshare.hitslink.com/operating-system-market-share.aspx?qprid=8|title = Operating System Market Share|access-date = December 11, 2009|last = Operating System Market Share|date = November 2009|url-status=live|archive-url = https://web.archive.org/web/20100125022803/http://marketshare.hitslink.com/operating-system-market-share.aspx?qprid=8|archive-date = January 25, 2010|df = mdy-all}}</ref> Some [[Free software license|free]] and [[Open-source license|open-source software licenses]] are based on the principle of [[Copyleft|copyleft]], a kind of reciprocity: any work derived from a copyleft piece of software must also be copyleft itself. The most common free software license, the GNU General Public License (GPL), is a form of copyleft, and is used for the Linux kernel and many of the components from the GNU Project.<ref>{{Cite web|title=gnu.org|url=https://www.gnu.org/licenses/copyleft.en.html|website=www.gnu.org|language=en|access-date=2020-05-12|archive-date=October 6, 2015|archive-url=https://web.archive.org/web/20151006133153/https://www.gnu.org/licenses/copyleft.en.html|url-status=live}}</ref>

Linux-based distributions are intended by developers for [[Engineering:Interoperability|interoperability]] with other operating systems and established computing standards. Linux systems adhere to POSIX,<ref>{{cite web | url = http://www.ukuug.org/newsletter/linux-newsletter/linux@uk21/posix.shtml | title = POSIX.1 (FIPS 151-2) Certification | url-status=live | archive-url = https://web.archive.org/web/20120226091425/http://www.ukuug.org/newsletter/linux-newsletter/linux@uk21/posix.shtml | archive-date = February 26, 2012 | df = mdy-all }}</ref> [[Single UNIX Specification|SUS]],<ref>{{cite web | title = How source code compatible is Debian with other Unix systems? | url = http://www.debian.org/doc/FAQ/ch-compat.en.html#s-otherunices | work = Debian FAQ | publisher = the Debian project | url-status=live | archive-url = https://web.archive.org/web/20111016004547/http://www.debian.org/doc/FAQ/ch-compat.en.html#s-otherunices | archive-date = October 16, 2011 | df = mdy-all }}</ref> [[Linux Standard Base|LSB]], [[Organization:International Organization for Standardization|ISO]], and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.<ref>{{cite web |url=http://www.linuxjournal.com/article/0131 |title=Certifying Linux |last=Eissfeldt |first=Heiko |date=August 1, 1996 |publisher=Linux Journal |archive-url=https://web.archive.org/web/20160404122450/http://www.linuxjournal.com/article/0131 |archive-date=April 4, 2016}}</ref><ref>{{cite web |url=http://www.debian.org/doc/FAQ/ch-compat.en.html |title=The Debian GNU/Linux FAQ – Compatibility issues |archive-url=https://web.archive.org/web/20111010111215/http://www.debian.org/doc/FAQ/ch-compat.en.html |archive-date=October 10, 2011 |access-date=September 17, 2011}}</ref>

Free software projects, although developed through [[Social:Collaboration|collaboration]], are often produced independently of each other. The fact that the software licenses explicitly permit redistribution, however, provides a basis for larger-scale projects that collect the software produced by stand-alone projects and make it available all at once in the form of a Linux distribution.

Many Linux distributions manage a remote collection of system software and application software packages available for download and installation through a network connection. This allows users to adapt the operating system to their specific needs. Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. A distribution is responsible for the default configuration of the installed Linux kernel, general system security, and more generally integration of the different software packages into a coherent whole. Distributions typically use a package manager such as [[Software:APT|apt]], [[Software:Yum|yum]], [[Software:ZYpp|zypper]], pacman or [[Software:Portage|portage]] to install, remove, and update all of a system's software from one central location.<ref>{{Cite web|title=The evolution of package managers|url=https://opensource.com/article/18/7/evolution-package-managers|last=comments|first=26 Jul 2018 Steve OvensFeed 151up 9|website=Opensource.com|language=en|access-date=2020-05-12|archive-date=July 26, 2018|archive-url=https://web.archive.org/web/20180726211300/https://opensource.com/article/18/7/evolution-package-managers|url-status=live}}</ref>

=== Community ===

A distribution is largely driven by its developer and user communities. Some vendors develop and fund their distributions on a volunteer basis, [[Software:Debian|Debian]] being a well-known example. Others maintain a community version of their commercial distributions, as [[Company:Red Hat|Red Hat]] does with [[Software:Fedora Linux|Fedora]], and [[Company:SUSE|SUSE]] does with [[Organization:OpenSUSE|openSUSE]].<ref>{{Cite web|url=http://getfedora.org/|title=Get Fedora|website=getfedora.org|language=en|access-date=2020-02-24|archive-date=July 11, 2020|archive-url=https://web.archive.org/web/20200711030627/https://getfedora.org/|url-status=live}}</ref><ref>{{Cite web|url=https://www.opensuse.org/|title=The makers' choice for sysadmins, developers and desktop users.|last=design|first=Cynthia Sanchez: front-end and UI, Zvezdana Marjanovic: graphic|website=openSUSE|access-date=2020-02-24|archive-date=August 5, 2005|archive-url=https://web.archive.org/web/20050805025740/https://www.opensuse.org/|url-status=live}}</ref>

In many cities and regions, local associations known as Linux User Groups (LUGs) seek to promote their preferred distribution and by extension free software. They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users. Many Internet communities also provide support to Linux users and developers. Most distributions and free software / open-source projects have [[Internet Relay Chat|IRC]] chatrooms or newsgroups. [[Internet forum|Online forums]] are another means for support, with notable examples being LinuxQuestions.org and the various distribution specific support and community forums, such as ones for [[Software:Ubuntu (operating system)|Ubuntu]], Fedora, and [[Software:Gentoo Linux|Gentoo]]. Linux distributions host [[Mailing list|mailing list]]s; commonly there will be a specific topic such as usage or development for a given list.

There are several technology websites with a Linux focus. Print magazines on Linux often bundle cover disks that carry software or even complete Linux distributions.<ref>{{cite web | url=http://www.linuxformat.co.uk/dvd/ | title=Linux Format DVD contents | author=Linux Format | access-date=January 17, 2008 |archive-url = https://web.archive.org/web/20080808113845/http://www.linuxformat.co.uk/dvd/|archive-date=August 8, 2008 }}</ref><ref>{{cite web | url=http://www.linux-magazine.com/resources/current_issue | title=Current Issue | author=linux-magazine.com | access-date=January 17, 2008 |  url-status=dead | archive-url=https://web.archive.org/web/20080110033853/http://www.linux-magazine.com/resources/current_issue | archive-date=January 10, 2008 | df=mdy-all }}</ref>

Although Linux distributions are generally available without charge, several large corporations sell, support, and contribute to the development of the components of the system and of free software. An analysis of the Linux kernel in 2017 showed that well over 85% of the code developed by programmers who are being paid for their work, leaving about 8.2% to unpaid developers and 4.1% unclassified.<ref name = "Linux Foundation 2021-11-14">{{Cite web|title=State of Linux Kernel Development 2017|url=https://www.linuxfoundation.org/tools/state-of-linux-kernel-development-2017/|access-date=2021-11-14|website=Linux Foundation|language=en-US|archive-date=November 14, 2021|archive-url=https://web.archive.org/web/20211114072617/https://www.linuxfoundation.org/tools/state-of-linux-kernel-development-2017/|url-status=live}}</ref> Some of the major corporations that provide contributions include [[Company:Intel|Intel]], [[Company:Samsung|Samsung]], [[Company:Google|Google]], [[Engineering:AMD|AMD]], [[Company:Oracle Corporation|Oracle]] and [[Company:Facebook|Facebook]].<ref name="Linux Foundation 2021-11-14" /> A number of corporations, notably Red Hat, [[Company:Canonical|Canonical]] and [[Company:SUSE|SUSE]], have built a significant business around Linux distributions.

The [[Free software license|free software license]]s, on which the various software packages of a distribution built on the Linux kernel are based, explicitly accommodate and encourage commercialization; the relationship between a Linux distribution as a whole and individual vendors may be seen as [[Earth:Symbiosis|symbiotic]]. One common [[Social:Business model|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 to sell hardware. This used to be the norm in the computer industry, with operating systems such as CP/M, [[Software:Apple DOS|Apple DOS]] and versions of the [[Software:Classic Mac OS|classic Mac OS]] prior to 7.6 freely copyable (but not modifiable). As computer hardware standardized throughout the 1980s, it became more difficult for hardware manufacturers to profit from this tactic, as the OS would run on any manufacturer's computer that shared the same architecture.

=== Programming on Linux ===
Most [[Programming language|programming language]]s support Linux either directly or through third-party community based [[Porting|ports]].<ref>{{cite web |url=https://gcc.gnu.org/wiki/GFortran |title=gfortran — the GNU Fortran compiler, part of GCC |website=GNU GCC |access-date=3 May 2020 |archive-date=April 18, 2020 |archive-url=https://web.archive.org/web/20200418073603/http://gcc.gnu.org/wiki/GFortran |url-status=live }}</ref> The original development tools used for building both Linux applications and operating system programs are found within the [[Software:GNU toolchain|GNU toolchain]], which includes the [[Software:GNU Compiler Collection|GNU Compiler Collection]] (GCC) and the [[Software:GNU Build System|GNU Build System]]. Amongst others, GCC provides compilers for [[Ada (programming language)|Ada]], C, [[C++]], [[Go (programming language)|Go]] and [[Fortran]]. Many programming languages have a cross-platform reference implementation that supports Linux, for example [[Organization:PHP|PHP]], [[Perl]], [[Ruby (programming language)|Ruby]], [[Python (programming language)|Python]], [[Java (programming language)|Java]], [[Go (programming language)|Go]], [[Rust (programming language)|Rust]] and [[Haskell]]. First released in 2003, the [[Software:LLVM|LLVM]] project provides an alternative cross-platform open-source compiler for many languages. [[Proprietary software|Proprietary]] compilers for Linux include the [[Software:Intel C++ Compiler|Intel C++ Compiler]], Sun Studio, and IBM XL C/C++ Compiler. [[BASIC]] is available in [[Procedural programming|procedural]] form from [[QB64]], [[PureBasic]], [[Software:Yabasic|Yabasic]], [[Software:GLBasic|GLBasic]], [[Basic4GL]], [[XBasic]], [[Software:WxBasic|wxBasic]], [[Software:SdlBasic|SdlBasic]], and [[Software:Basic-256|Basic-256]], as well as object oriented through [[Gambas]], [[FreeBASIC]], [[Software:B4X|B4X]], Basic for Qt, Phoenix Object Basic, [[Software:NS Basic|NS Basic]], [[ProvideX]], [[Chipmunk Basic]], [[Software:RapidQ|RapidQ]] and [[Software:Xojo|Xojo]]. [[Pascal (programming language)|Pascal]] is implemented through [[Software:GNU Pascal|GNU Pascal]], [[Software:Free Pascal|Free Pascal]], and [[Software:Virtual Pascal|Virtual Pascal]], as well as graphically via [[Software:Lazarus|Lazarus]], [[PascalABC.NET]], or [[Software:Delphi|Delphi]] using [[Software:FireMonkey|FireMonkey]] (previously through [[Software:Borland Kylix|Borland Kylix]]).

A common feature of Unix-like systems, Linux includes traditional specific-purpose programming languages targeted at [[Scripting language|scripting]], text processing and system configuration and management in general. Linux distributions support [[Shell script|shell script]]s, [[AWK|awk]], [[Sed|sed]] and [[Software:Make|make]]. Many programs also have an embedded programming language to support configuring or programming themselves. For example, [[Regular expression|regular expression]]s are supported in programs like [[Software:Grep|grep]] and [[Software:Locate (Unix)|locate]], the traditional Unix message transfer agent [[Software:Sendmail|Sendmail]] contains its own [[Turing completeness|Turing complete]] scripting system, and the advanced text editor [[Software:GNU Emacs|GNU Emacs]] is built around a general purpose [[Emacs Lisp|Lisp]] interpreter.

Most distributions also include support for [[Organization:PHP|PHP]], [[Perl]], [[Ruby (programming language)|Ruby]], [[Python (programming language)|Python]] and other [[Dynamic programming language|dynamic languages]]. While not as common, Linux also supports [[C Sharp (programming language)|C#]] and other [[Common Language Infrastructure|CLI]] [[List of CLI languages|languages]] (via [[Software:Mono|Mono]]), [[Vala (programming language)|Vala]], and [[Scheme (programming language)|Scheme]]. Guile Scheme acts as an [[Scripting language|extension language]] targeting the GNU system utilities, seeking to make the conventionally small, static, compiled C programs of [[Philosophy:Unix philosophy|Unix design]] rapidly and dynamically extensible via an elegant, [[Functional programming|functional]] high-level scripting system; many GNU programs can be compiled with optional Guile [[Language binding|bindings]] to this end. A number of [[Java virtual machine]]s and development kits run on Linux, including the original Sun Microsystems JVM ([[Software:HotSpot (virtual machine)|HotSpot]]), and IBM's J2SE RE, as well as many open-source projects like [[Software:Kaffe|Kaffe]] and [[Software:Jikes RVM|Jikes RVM]]; [[Kotlin (programming language)|Kotlin]], [[Scala (programming language)|Scala]], [[Apache Groovy|Groovy]] and other [[List of JVM languages|JVM languages]] are also available.


== Hardware support ==
[[File:Linux kernel ubiquity.svg|thumb|right|upright=2.25|Linux is ubiquitously found on various types of hardware.]]

The Linux kernel is a widely ported operating system kernel, available for devices ranging from mobile phones to supercomputers; it runs on a highly diverse range of [[Computer architecture|computer architecture]]s, including [[ARM architecture family|ARM]]-based Android smartphones and the [[IBM Z]] mainframes. Specialized distributions and kernel forks exist for less mainstream architectures; for example, the [[Software:Embeddable Linux Kernel Subset|ELKS]] kernel [[Software:Fork (software development)|fork]] can run on [[Engineering:Intel 8086|Intel 8086]] or [[Engineering:Intel 80286|Intel 80286]] 16-bit microprocessors, while the [[Software:ΜClinux|µClinux]] kernel fork may run on systems without a [[Memory management unit|memory management unit]]. The kernel also runs on architectures that were only ever intended to use a proprietary manufacturer-created operating system, such as [[Engineering:Macintosh|Macintosh]] computers<ref>{{Cite web|last=Das|first=Ankush|date=2021-01-21|title=Finally! Linux Runs Gracefully On Apple M1 Chip|url=https://news.itsfoss.com/linux-apple-m1/|access-date=2021-11-13|website=It's FOSS News|language=en-US|archive-date=November 13, 2021|archive-url=https://web.archive.org/web/20211113113053/https://news.itsfoss.com/linux-apple-m1/|url-status=live}}</ref><ref>{{Cite news|last=Jimenez|first=Jorge|date=2021-10-08|title=Developers finally get Linux running on an Apple M1-powered Mac|language=en|work=PC Gamer|url=https://www.pcgamer.com/developers-finally-get-linux-running-on-an-apple-m1-powered-mac/|access-date=2021-11-13|archive-date=January 11, 2023|archive-url=https://web.archive.org/web/20230111042438/https://www.pcgamer.com/developers-finally-get-linux-running-on-an-apple-m1-powered-mac/|url-status=live}}</ref> (with [[PowerPC]], [[Company:Intel|Intel]], and [[Engineering:Apple silicon|Apple silicon]] processors), [[Social:Personal digital assistant|PDAs]], [[Engineering:Video game console|video game console]]s, [[Engineering:Portable media player|portable music players]], and mobile phones.

Linux has a reputation of supporting old hardware very well by maintaining standardized drivers for a long time.<ref>{{Cite web |last=Proven |first=Liam |date=2022-11-10 |title=OpenPrinting keeps old printers working, even on Windows |url=https://www.theregister.com/2022/11/10/openprinting_keeps_old_printers_working/ |access-date=2023-01-07 |website=The Register |language=en |archive-date=January 7, 2023 |archive-url=https://web.archive.org/web/20230107164300/https://www.theregister.com/2022/11/10/openprinting_keeps_old_printers_working/ |url-status=live }}</ref> There are several industry associations and hardware conferences devoted to maintaining and improving support for diverse hardware under Linux, such as FreedomHEC. Over time, support for different hardware has improved in Linux, resulting in any off-the-shelf purchase having a "good chance" of being compatible.<ref>{{cite web |url=http://www.linux.com/news/hardware/drivers/8203-is-my-hardware-linux-compatible-find-out-here |title=Is my hardware Linux-compatible? Find out here |date=August 14, 2007 |author=Bruce Byfield |website=Linux.com |access-date=September 4, 2015 |url-status=live |archive-url=https://web.archive.org/web/20150905214148/http://www.linux.com/news/hardware/drivers/8203-is-my-hardware-linux-compatible-find-out-here |archive-date=September 5, 2015}}</ref>

In 2014, a new initiative was launched to automatically collect a database of all tested hardware configurations.<ref name="linuxhw">{{cite web | url = https://linux-hardware.org/ | title = Linux Hardware | access-date = 2020-06-26 | publisher = Linux Hardware Project | archive-date = January 26, 2021 | archive-url = https://web.archive.org/web/20210126054431/https://linux-hardware.org/ | url-status = live }}</ref>

== Uses ==
{{Main|Linux range of use}}

== Market share and uptake ==
{{Main|Linux adoption}}

Many quantitative studies of free/open-source software focus on topics including market share and reliability, with numerous studies specifically examining Linux.<ref>{{cite web | first = David A | last = Wheeler | url = http://www.dwheeler.com/oss_fs_why.html | title = Why Open Source Software/Free Software (OSS/FS)? Look at the Numbers! | access-date = April 1, 2006 | url-status=live | archive-url = https://web.archive.org/web/20060405112628/http://www.dwheeler.com/oss_fs_why.html | archive-date = April 5, 2006 | df = mdy-all }}</ref> The Linux market is growing, and the Linux operating system market size is expected to see a growth of 19.2% by 2027, reaching $15.64 billion, compared to $3.89 billion in 2019.<ref>{{Cite web|title=Linux Operating System Market Size, Share and Forecast [2020-2027]|url=https://www.fortunebusinessinsights.com/linux-operating-system-market-103037|access-date=2021-11-12|website=www.fortunebusinessinsights.com|archive-date=November 12, 2021|archive-url=https://web.archive.org/web/20211112140435/https://www.fortunebusinessinsights.com/linux-operating-system-market-103037|url-status=live}}</ref> Analysts project a Compound Annual Growth Rate (CAGR) of 13.7% between 2024 and 2032, culminating in a market size of USD 34.90 billion by the latter year.<ref>{{Cite web|title=Linux Operating System Market Size, Share, Trends 2024-2032|url=https://www.expertmarketresearch.com/reports/linux-operating-system-market|access-date=December 25, 2023|website=www.expertmarketresearch.com|archive-date=February 3, 2023|archive-url=https://web.archive.org/web/20230203112541/https://www.expertmarketresearch.com/reports/linux-operating-system-market|url-status=live}}</ref> Analysts and proponents attribute the relative success of Linux to its security, reliability, low cost, and freedom from [[Social:Vendor lock-in|vendor lock-in]].<ref>{{cite web | url = http://www.ca.com/za/news/2005/20051010_linux.htm| archive-url = https://web.archive.org/web/20070217125550/http://www.ca.com/za/news/2005/20051010_linux.htm| archive-date = February 17, 2007| title = The rise and rise of Linux|date=October 10, 2005|publisher=Computer Associates International}}</ref><ref>{{cite web | url = http://www-306.ibm.com/software/info/features/feb152005/ | archive-url = https://web.archive.org/web/20080603232638/http://www-306.ibm.com/software/info/features/feb152005/ | archive-date = June 3, 2008 | title = Why customers are flocking to Linux |author=Jeffrey S. Smith|publisher=IBM}}</ref>

; Desktops and laptops
: According to [[Web analytics|web server statistics]] (that is, based on the numbers recorded from visits to websites by client devices), {{as of|2022|05|lc=y}}, the estimated market share of Linux on [[Engineering:Desktop computer|desktop computer]]s is around 2.5%. In comparison, [[Software:Microsoft Windows|Microsoft Windows]] has a market share of around 75.5%, while [[Software:MacOS|macOS]] covers around 14.9%.<ref name="statcounter-desktop" />

; Web servers

: W3Cook publishes stats that use the top 1,000,000 Alexa domains,<ref>{{cite web|title=W3Cook FAQ|url=http://www.w3cook.com/faq/home|website=W3Cook.com|access-date=June 30, 2015|url-status=dead|archive-url=https://web.archive.org/web/20150627014517/http://www.w3cook.com/faq/home|archive-date=June 27, 2015}}</ref> which {{as of|2015|5|lc=yes}} estimate that 96.55% of web servers run Linux, 1.73% run Windows, and 1.72% run FreeBSD.<ref>{{cite web|title=OS Market Share and Usage Trends|url=http://www.w3cook.com/os/summary/|website=W3Cook.com|access-date=June 30, 2015|archive-url = https://web.archive.org/web/20150806093859/http://www.w3cook.com/os/summary//|archive-date = August 6, 2015}}</ref>

:W3Techs publishes stats that use the top 10,000,000 Alexa domains and the top 1,000,000 Tranco domains, updated monthly<ref>{{cite web|title=Technologies Overview - methodology information|url=http://w3techs.com/technologies|website=W3Techs|access-date=June 30, 2015}}</ref> and {{as of|November 2020|lc=true}} estimate that Linux is used by 39% of the web servers, versus 21.9% being used by [[Software:Microsoft Windows|Microsoft Windows]].<ref>{{Cite web|title=Linux vs. Windows usage statistics, November 2021|url=https://w3techs.com/technologies/comparison/os-linux,os-windows|access-date=2021-11-14|website=w3techs.com|archive-date=January 11, 2023|archive-url=https://web.archive.org/web/20230111042441/https://w3techs.com/technologies/comparison/os-linux,os-windows|url-status=live}}</ref> 40.1% used other types of Unix.<ref>{{Cite web|title=Usage Statistics and Market Share of Unix for Websites, November 2021|url=https://w3techs.com/technologies/details/os-unix|access-date=2021-11-14|website=w3techs.com|archive-date=January 11, 2023|archive-url=https://web.archive.org/web/20230111042439/https://w3techs.com/technologies/details/os-unix|url-status=live}}</ref>

:[[Company:International Data Corporation|IDC]]'s Q1 2007 report indicated that Linux held 12.7% of the overall server market at that time;<ref name="Linux-watch.com IDC's Q1 2007 report">{{cite web |url=http://www.linux-watch.com/news/NS5369154346.html |title=─ IDC Q1 2007 report |publisher=Linux-watch.com |date=May 29, 2007 |access-date=March 9, 2009 |url-status=dead |archive-url=https://www.webcitation.org/5mq1DzaMY?url=http://www.linux-watch.com/news/NS5369154346.html |archive-date=January 17, 2010}}</ref> this estimate was based on the number of Linux servers sold by various companies, and did not include server hardware purchased separately that had Linux installed on it later.

; Mobile devices
: Android, which is based on the Linux kernel, has become the dominant operating system for smartphones. In April 2023, 68.61% of mobile devices accessing websites using [[Company:StatCounter|StatCounter]] were from Android.<ref>{{Cite web |title=Mobile Operating System Market Share Worldwide |url=https://gs.statcounter.com/os-market-share/mobile/worldwide |access-date=2023-05-30 |website=StatCounter Global Stats |language=en |archive-date=October 11, 2020 |archive-url=https://web.archive.org/web/20201011012110/https://gs.statcounter.com/os-market-share/mobile/worldwide |url-status=live }}</ref> Android is also a popular operating system for tablets, being responsible for more than 60% of tablet sales {{as of|2013|lc=true}}.<ref>{{Cite news|url = http://www.gartner.com/newsroom/id/2674215|title = Gartner Says Worldwide Tablet Sales Grew 68 Percent in 2013, With Android Capturing 62 Percent of the Market|last = Egham|date = March 3, 2014|access-date = June 13, 2014|url-status=dead|archive-url = https://web.archive.org/web/20140417073251/http://www.gartner.com/newsroom/id/2674215|archive-date = April 17, 2014|df = mdy-all}}</ref> According to web server statistics, {{as of|2021|10|lc=yes}} Android has a market share of about 71%, with [[Software:IOS|iOS]] holding 28%, and the remaining 1% attributed to various niche platforms.<ref>{{cite web|title=Mobile/Tablet Operating System Market Share|url=https://netmarketshare.com/operating-system-market-share.aspx?options=%7B%22filter%22%3A%7B%22%24and%22%3A%5B%7B%22deviceType%22%3A%7B%22%24in%22%3A%5B%22Mobile%22%5D%7D%7D%5D%7D%2C%22dateLabel%22%3A%22Trend%22%2C%22attributes%22%3A%22share%22%2C%22group%22%3A%22platform%22%2C%22sort%22%3A%7B%22share%22%3A-1%7D%2C%22id%22%3A%22platformsMobile%22%2C%22dateInterval%22%3A%22Monthly%22%2C%22dateStart%22%3A%222019-11%22%2C%22dateEnd%22%3A%222020-10%22%2C%22segments%22%3A%22-1000%22%7D|website=Netmarketshare.com|access-date=October 14, 2021|url-status=live|archive-url=https://web.archive.org/web/20210628033222/https://netmarketshare.com/operating-system-market-share.aspx?options=%7B%22filter%22%3A%7B%22%24and%22%3A%5B%7B%22deviceType%22%3A%7B%22%24in%22%3A%5B%22Mobile%22%5D%7D%7D%5D%7D%2C%22dateLabel%22%3A%22Trend%22%2C%22attributes%22%3A%22share%22%2C%22group%22%3A%22platform%22%2C%22sort%22%3A%7B%22share%22%3A-1%7D%2C%22id%22%3A%22platformsMobile%22%2C%22dateInterval%22%3A%22Monthly%22%2C%22dateStart%22%3A%222019-11%22%2C%22dateEnd%22%3A%222020-10%22%2C%22segments%22%3A%22-1000%22%7D|archive-date=June 28, 2021}}</ref>

; Film production
: For years, Linux has been the platform of choice in the film industry. The first major film produced on Linux servers was 1997's ''Titanic''.<ref>{{cite web|last=Strauss|first=Daryll|title=Linux Helps Bring Titanic to Life|url=http://www.linuxjournal.com/article/2494?page=0,0|access-date=July 28, 2011|url-status=dead|archive-url=https://web.archive.org/web/20120112151726/http://www.linuxjournal.com/article/2494?page=0,0|archive-date=January 12, 2012}}</ref><ref>{{cite web|last=Rowe|first=Robin|title=Linux and Star Trek|url=http://www.linuxjournal.com/article/6339|access-date=July 28, 2011|url-status=dead|archive-url=https://web.archive.org/web/20110712200616/http://www.linuxjournal.com/article/6339|archive-date=July 12, 2011}}</ref> Since then major studios including DreamWorks Animation, Pixar, [[Company:Weta Digital|Weta Digital]], and Industrial Light & Magic have migrated to Linux.<ref>{{cite web | url = http://www.linuxjournal.com/article/5472 | title = Industry of Change: Linux Storms Hollywood | access-date = March 11, 2009 | url-status = dead | archive-url = https://web.archive.org/web/20090411054311/http://www.linuxjournal.com/article/5472 | archive-date = April 11, 2009 | df = mdy-all }}</ref><ref>{{cite web | url = http://video.fosdem.org/2008/maintracks/FOSDEM2008-tuxwithshades.ogg | title = Tux with Shades, Linux in Hollywood | access-date = March 11, 2009 | archive-date = January 11, 2023 | archive-url = https://web.archive.org/web/20230111042527/https://ftp.heanet.ie/mirrors/fosdem-video/2008/maintracks/FOSDEM2008-tuxwithshades.ogg | url-status = live }}</ref><ref>{{cite web | url = http://www.wetafx.co.nz/jobs/ | title = Weta Digital – Jobs | access-date = November 17, 2010 | url-status = dead | archive-url = https://web.archive.org/web/20101230083916/http://www.wetafx.co.nz/jobs | archive-date = December 30, 2010 | df = mdy-all }}</ref> According to the Linux Movies Group, more than 95% of the servers and desktops at large animation and visual effects companies use Linux.<ref>{{cite web | url = http://www.linuxmovies.org/2011/06/26/linux-movies-hollywood-loves-linux/ | title = LinuxMovies.org – Advancing Linux Motion Picture Technology | access-date = March 16, 2012 | url-status=dead | archive-url = https://web.archive.org/web/20120301232751/http://www.linuxmovies.org/2011/06/26/linux-movies-hollywood-loves-linux/ | archive-date = March 1, 2012 | df = mdy-all }}</ref>

; Use in government
: Linux distributions have also gained popularity with various local and national governments. News of the Russian military creating its own Linux distribution has also surfaced, and has come to fruition as the G.H.ost Project.<ref>{{cite web | url = http://www.osor.eu/news/lv-minister-open-standards-improve-efficiency-and-transparency | title = LV: Minister: "Open standards improve efficiency and transparency" | access-date = February 21, 2009 | url-status=live | archive-url = https://web.archive.org/web/20110809142726/http://www.osor.eu/news/lv-minister-open-standards-improve-efficiency-and-transparency | archive-date = August 9, 2011 | df = mdy-all }}</ref> The Indian state of Kerala has gone to the extent of mandating that all state high schools run Linux on their computers.<ref>{{cite web | url = http://www.businessweek.com/globalbiz/content/sep2006/gb20060921_463452.htm | title = Linux Spreads its Wings in India | access-date = February 21, 2009 | url-status=dead | archive-url = https://web.archive.org/web/20110728114950/http://www.businessweek.com/globalbiz/content/sep2006/gb20060921_463452.htm | archive-date = July 28, 2011 | df = mdy-all }}</ref><ref>{{cite web | url = http://www.indianexpress.com/news/kerala-shuts-windows-schools-to-use-only-linux/280323/0 | title = Kerala shuts windows, schools to use only Linux | date = March 4, 2008 | access-date = June 22, 2009 | url-status=live | archive-url = https://web.archive.org/web/20110515032441/http://www.indianexpress.com/news/kerala-shuts-windows-schools-to-use-only-linux/280323/0 | archive-date = May 15, 2011 | df = mdy-all }}</ref> China uses Linux exclusively as the operating system for its [[Company:Loongson|Loongson]] processor family to achieve technology independence.<ref>{{cite web|url=http://www.mdronline.com/watch/watch_Issue.asp?Volname=Issue+%23110308&on=1 |title=China's Microprocessor Dilemma |publisher=Microprocessor Report |url-access=subscription |archive-url=https://web.archive.org/web/20090918002910/http://www.mdronline.com/watch/watch_Issue.asp?Volname=Issue%2B%23110308&on=1 |archive-date=September 18, 2009 |url-status=dead |access-date=April 15, 2009 }}</ref> In Spain, some regions have developed their own Linux distributions, which are widely used in education and official institutions, like gnuLinEx in Extremadura and Guadalinex in Andalusia. {{wipe|France}} and {{wipe|Germany}} have also taken steps toward the adoption of Linux.<ref>{{cite news | url=http://seattlepi.com/business/48925_linuxop01.shtml | title=Some countries are choosing Linux systems over Microsoft | access-date=February 21, 2009 | work=Seattle Post-Intelligencer | first=Jim | last=Krane | date=November 30, 2001 | url-status=live | archive-url=https://web.archive.org/web/20120315075128/http://www.seattlepi.com/business/article/Some-countries-are-choosing-Linux-systems-over-1073338.php | archive-date=March 15, 2012 | df=mdy-all }}</ref> North Korea's [[Software:Red Star OS|Red Star OS]], developed {{as of|2002|lc=true}}, is based on a version of Fedora Linux.<ref>{{cite news | url = https://www.theguardian.com/world/2015/dec/27/north-koreas-computer-operating-system-revealed-by-researchers | title = North Korea's 'paranoid' computer operating system revealed | access-date = December 31, 2015 | work = The Guardian | date = December 27, 2015 | url-status=live | archive-url = https://web.archive.org/web/20151231021946/http://www.theguardian.com/world/2015/dec/27/north-koreas-computer-operating-system-revealed-by-researchers | archive-date = December 31, 2015 | df = mdy-all }}</ref>

== Copyright, trademark, and naming ==

The Linux kernel is [[Software license|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.<ref>{{cite web | url = https://www.gnu.org/licenses/gpl-2.0.html | title = GNU General Public License, version 2 | date = June 2, 1991 | access-date = December 5, 2013 | publisher = GNU Project | url-status=live | archive-url = https://web.archive.org/web/20131207171309/http://www.gnu.org/licenses/gpl-2.0.html | archive-date = December 7, 2013 | df = mdy-all }}</ref> 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 [[Software:GNU Lesser General Public License|GNU Lesser General Public License]] (LGPL), a more permissive variant of the GPL, and the [[Software:X.Org Server|X.Org]] implementation of the X Window System uses the [[Software:MIT License|MIT License]].

Torvalds states that the Linux kernel will not move from version 2 of the GPL to version 3.<ref>{{cite web | url=https://lkml.org/lkml/2006/1/25/273 | title=Re: GPL V3 and Linux ─ Dead Copyright Holders | author=Torvalds, Linus | date=January 26, 2006 | publisher=Linux Kernel Mailing List | url-status=live | archive-url=https://web.archive.org/web/20140709004223/https://lkml.org/lkml/2006/1/25/273 | archive-date=July 9, 2014 | df=mdy-all }}</ref><ref>{{cite web | url=https://lkml.org/lkml/2006/9/25/161 | title=Re: GPLv3 Position Statement | author=Torvalds, Linus | date=September 25, 2006 | publisher=Linux Kernel Mailing List | url-status=live | archive-url=https://web.archive.org/web/20140422105221/http://lkml.org/lkml/2006/9/25/161 | archive-date=April 22, 2014 | df=mdy-all }}</ref> He specifically dislikes some provisions in the new license which prohibit the use of the software in [[Engineering:Digital rights management|digital rights management]].<ref>{{cite web | url = https://gnu.org/licenses/quick-guide-gplv3.html#neutralizing-laws-that-prohibit-free-software-but-not-forbidding-drm | title = Neutralizing Laws That Prohibit Free Software — But Not Forbidding DRM | work = A Quick Guide to GPLv3 | date = July 29, 2013 | access-date = December 5, 2013 | author = Brett Smith | publisher = GNU Project | url-status=live | archive-url = https://web.archive.org/web/20131201091449/http://www.gnu.org/licenses/quick-guide-gplv3.html#neutralizing-laws-that-prohibit-free-software-but-not-forbidding-drm | archive-date = December 1, 2013 | df = mdy-all }}</ref> It would also be impractical to obtain permission from all the copyright holders, who number in the thousands.<ref>{{cite web |url=http://www.linux-watch.com/news/NS3301105877.html |archive-url=https://archive.today/20130103161648/http://www.linux-watch.com/news/NS3301105877.html |url-status=dead |archive-date=January 3, 2013 |title=Keeping an Eye on the Penguin |publisher=Linux-watch.com |date=February 7, 2006 |access-date=November 9, 2010 }}</ref>

A 2001 study of [[Software:Red Hat Linux|Red Hat Linux]] 7.1 found that this distribution contained 30 million [[Source lines of code|source lines of code]].<ref name = "estimating_size"/> Using the Constructive Cost Model, the study estimated that this distribution required about eight thousand person-years of development time. According to the study, if all this software had been developed by conventional proprietary means, it would have cost about {{USD}}{{Format price|{{inflation|US-GDP|1080000000|2000}}}}{{Inflation/fn|US-GDP}} to develop in {{Inflation/year|US-GDP}} in the United States.<ref name="estimating_size">{{cite web | first = David A | last = Wheeler | date = July 29, 2002 | url = http://www.dwheeler.com/sloc/redhat71-v1/redhat71sloc.html | title = More Than a Gigabuck: Estimating GNU/Linux's Size | access-date = May 11, 2006 | url-status=dead | archive-url = https://web.archive.org/web/20060421145300/http://dwheeler.com/sloc/redhat71-v1/redhat71sloc.html | archive-date = April 21, 2006 | df = mdy-all }}</ref> Most of the source code (71%) was written in the C programming language, but many other languages were used, including [[C++]], [[Lisp (programming language)|Lisp]], assembly language, Perl, Python, [[Fortran]], and various [[Shell script|shell script]]ing 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.<ref name="estimating_size" />

In a later study, the same analysis was performed for Debian version 4.0 (etch, which was released in 2007).<ref>{{cite web | first1 = Juan José | last1 = Amor | date = June 17, 2007 | url = http://libflow.com/d/8drl8n07/Measuring_Etch%3A_The_Size_of_Debian_4.0 | title = Measuring Etch: the size of Debian 4.0 | access-date = September 16, 2007 | display-authors = etal | url-status=live | archive-url = https://web.archive.org/web/20140728033855/http://libflow.com/d/8drl8n07/Measuring_Etch%3A_The_Size_of_Debian_4.0 | archive-date = July 28, 2014 | df = mdy-all }}</ref> This distribution contained close to 283 million source lines of code, and the study estimated that it would have required about seventy three thousand man-years and cost {{USD}}{{Format price|{{inflation|US-GDP|7170186240|2007}}}}{{Inflation/fn|US-GDP}} (in {{Inflation/year|US-GDP}} dollars) to develop by conventional means. <!-- original paper quoted 5358000000 euros, but Wikipedia does not have an inflation calculator for euros; converted to USD via June 17, 2007 exchange rate as provided by http://www.bankofcanada.ca/en/rates/exchform.html and double-checked against other sources of historical exchange rates ... it is also more useful to quote the number in dollars, for comparison to other dollar amounts quoted in this article, e.g. the 2001 study above -->

{{Anchor|POWDER}}
[[File:LinuxWasch3.jpg|thumb|right|The name "Linux" is also used for a laundry detergent made by Swiss company Rösch.<ref>{{cite web |date=June 19, 2015 |title=There Is a Linux Detergent Out There and It's Trademarked |url=https://www.linux.com/news/software/applications/836277-there-is-a-linux-detergent-out-there-and-its-trademarked/ |url-status=dead |archive-url=https://web.archive.org/web/20150624032318/http://www.linux.com/news/software/applications/836277-there-is-a-linux-detergent-out-there-and-its-trademarked |archive-date=June 24, 2015 |access-date=January 31, 2016 |website=Linux.com}}</ref>]]

In the United States, the name ''Linux'' is a trademark registered to Linus Torvalds.<ref name="US_trademark"/> Initially, nobody registered it. However, on August 15, 1994, William R. 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.<ref>{{cite web | url = http://www.linuxjournal.com/article/9065 | title = Linux Timeline | publisher = Linux Journal | date = May 31, 2006 | url-status=live | archive-url = https://web.archive.org/web/20130203160342/http://www.linuxjournal.com/article/9065 | archive-date = February 3, 2013 | df = mdy-all }}</ref> The licensing of the trademark has since been handled by the [[Organization:Linux Mark Institute|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,<ref>{{cite news |author=Neil McAllister |title=Linus gets tough on Linux trademark |url=http://www.infoworld.com/article/05/09/05/36OPopenent_1.html |work=InfoWorld |date=September 5, 2005 |access-date=February 24, 2008 |archive-url=https://web.archive.org/web/20080412055615/http://www.infoworld.com/article/05/09/05/36OPopenent_1.html |archive-date=April 12, 2008}}</ref> but later changed this in favor of offering a free, perpetual worldwide sublicense.<ref>{{cite web | url = http://www.linuxmark.org | title = Linux Mark Institute | access-date = February 24, 2008 | quote = LMI has restructured its sublicensing program. Our new sublicense agreement is: Free – approved sublicense holders pay no fees; Perpetual – sublicense terminates only in breach of the agreement or when your organization ceases to use its mark; Worldwide – one sublicense covers your use of the mark anywhere in the world | url-status=live | archive-url = https://web.archive.org/web/20080213024227/http://www.linuxmark.org/ | archive-date = February 13, 2008 | df = mdy-all }}</ref>

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 [[Software:GNU variants|variants]] of the GNU operating system initiated in 1983 by [[Biography:Richard Stallman|Richard Stallman]], president of the FSF.<ref name="gnu_linux_faq">{{cite web | url = https://www.gnu.org/gnu/gnu-linux-faq.html | title = GNU/Linux FAQ | publisher = Gnu.org | access-date = September 1, 2013 | url-status=live | archive-url = https://web.archive.org/web/20130907132420/http://www.gnu.org/gnu/gnu-linux-faq.html | archive-date = September 7, 2013 | df = mdy-all }}</ref><ref name="linux-and-gnu" /> They explicitly take no issue over the name Android for the Android OS, which is also an operating system based on the Linux kernel, as GNU is not a part of it.

A minority of public figures and software projects other than Stallman and the FSF, notably Debian (which had been sponsored by the FSF up to 1996),<ref>{{cite web |url=http://tech-insider.org/free-software/research/1996/0428.html |title=The FSF is no longer sponsoring Debian |date=April 28, 1996 |access-date=February 8, 2014 |author=Richard Stallman |publisher=tech-insider.org |url-status=live |archive-url=https://web.archive.org/web/20140221230241/http://tech-insider.org/free-software/research/1996/0428.html |archive-date=February 21, 2014}}</ref> also use ''GNU/Linux'' when referring to the operating system as a whole.<ref name="tivo">{{cite web | url = http://www.tivo.com/linux/linux.asp | title = TiVo ─ GNU/Linux Source Code |access-date=December 12, 2006 |archive-url=https://web.archive.org/web/20070519150730/http://www.tivo.com/linux/linux.asp |archive-date=May 19, 2007}}</ref><ref>{{cite web |url=http://www.debian.org/intro/about |title=About Debian |publisher=debian.org |date=December 8, 2013 |access-date=January 30, 2014 |url-status=live |archive-url=https://web.archive.org/web/20140123071309/http://www.debian.org/intro/about |archive-date=January 23, 2014}}</ref><ref>{{cite web |url=http://vger.kernel.org/lkml/#s1-1 |title=The linux-kernel mailing list FAQ |author1=Andrew D. Balsa |display-authors=et al|date=October 17, 2009 |website=vger.kernel.org |archive-url=https://web.archive.org/web/20121001231709/http://vger.kernel.org/lkml/ |archive-date=October 1, 2012 |url-status=live |access-date=June 13, 2013 |quote=...we have tried to use the word "Linux" or the expression "Linux kernel" to designate the kernel, and GNU/Linux to designate the entire body of GNU/GPL'ed OS software,... ...many people forget that the linux kernel mailing list is a forum for discussion of kernel-related matters, not GNU/Linux in general...}}</ref> Most media and common usage, however, refers to this family of operating systems simply as ''Linux'', as do many large Linux distributions (for example, [[Software:SUSE Linux|SUSE Linux]] and [[Software:Red Hat Enterprise Linux|Red Hat Enterprise Linux]]). By contrast, Linux distributions containing only free software use "GNU/Linux" or simply "GNU", such as Trisquel GNU/Linux, Parabola GNU/Linux-libre, [[Software:BLAG Linux and GNU|BLAG Linux and GNU]], and [[Software:GNewSense|gNewSense]].

{{As of|2011|May}}, about 8% to 13% of the [[Source lines of code|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.<ref name="how-much-gnu">{{cite web|url=http://pedrocr.pt/text/how-much-gnu-in-gnu-linux/|title=How much GNU is there in GNU/Linux?|last=Côrte-Real|first=Pedro|date=May 31, 2011|work=Split Perspective|access-date=January 28, 2014|url-status=live|archive-url=https://web.archive.org/web/20140207120339/http://pedrocr.pt/text/how-much-gnu-in-gnu-linux/|archive-date=February 7, 2014}} (self-published data)</ref>

== See also ==

{{Div col|colwidth=25em}}
* [[Software:Comparison of Linux distributions|Comparison of Linux distributions]]
* [[Software:Comparison of open-source and closed-source software|Comparison of open-source and closed-source software]]
* [[Software:Comparison of operating systems|Comparison of operating systems]]
* [[Software:Comparison of X Window System desktop environments|Comparison of X Window System desktop environments]]
* [[Criticism of Linux]]
* [[Software:Linux kernel version history|Linux kernel version history]]
* Linux Documentation Project
* [[Software:Linux From Scratch|Linux From Scratch]]
* [[Linux Software Map]]
* [[Software:List of Linux distributions|List of Linux distributions]]
* [[Software:List of Linux games|List of games released on Linux]]
* [[Software:List of operating systems|List of operating systems]]
* [[Software:Loadable kernel module|Loadable kernel module]]
* [[Software:Usage share of operating systems|Usage share of operating systems]]
* [[Software:Timeline of operating systems|Timeline of operating systems]]
{{div col end}}

== Notes ==
{{Notelist}}

== References ==
{{reflist}}

== External links ==
* {{curlie|Computers/Software/Operating_Systems/Linux|Linux}}
* [https://web.archive.org/web/20100211130125/http://www.makelinux.net/system/new Graphical map of Linux Internals] (archived)
* [https://www.kernel.org/ Linux kernel website and archives]
* [https://archive.org/details/git-history-of-linux The History of Linux in GIT Repository Format 1992–2010] (archived)

{{Linux}}
{{Linux distributions}}
{{Unix}}
{{FOSS}}
{{Operating system}}


[[Category:Linux| ]]
[[Category:Computing platforms]]
[[Category:Cross-platform software]]
[[Category:Free software programmed in C]]
[[Category:Operating systems]]
[[Category:Unix variants]]

{{Sourceattribution|Linux}}