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108-475: Released under the terms of version 3 or later of the GNU General Public License , GNU Screen is free software . GNU Screen can be thought of as a text version of graphical window managers , or as a way of putting virtual terminals into any login session. It is a wrapper that allows multiple text programs to run at the same time, and provides features that allow the user to use the programs within

216-678: A Balkanisation of the "Open Source Universe". Linus Torvalds, who decided not to adopt the GPLv3 for the Linux kernel, reiterated his criticism several years later. GPLv3 improved compatibility with several free software licenses such as the Apache License, version 2.0, and the GNU Affero General Public License, which GPLv2 could not be combined with. However, GPLv3 software could only be combined and share code with GPLv2 software if

324-472: A high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, AT&T licensed the operating system's source code as a trade secret to anyone who asked. 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

432-424: A minimalist functionality, while more elaborate window managers such as FVWM , Enlightenment , or Window Maker provide more features such as a built-in taskbar and themes , but are still lightweight when compared to desktop environments. Desktop environments include window managers as part of their standard installations, such as Mutter (GNOME), KWin (KDE), or Xfwm (xfce), although users may choose to use

540-601: A patent infringement claim or other litigation to impair users' freedom under the license. By 1990, it was becoming apparent that a less restrictive license would be strategically useful for the C library and for software libraries that essentially did the job of existing proprietary ones; when version 2 of the GPL (GPLv2) was released in June 1991, therefore, a second license – the GNU Library General Public License –

648-437: A solution stack such as LAMP . The source code of Linux may be used, modified, and distributed commercially or non-commercially by anyone under the terms of its respective licenses, such as the GNU General Public License (GPL). The license means creating novel distributions is permitted by anyone and is easier than it would be for an operating system such as MacOS or Microsoft Windows . The Linux kernel, for example,

756-452: A "user" and a "consumer product". It also explicitly removed the section on "Geographical Limitations", the probable removal of this section having been announced at the launch of the public consultation. The fourth discussion draft, which was the last, was released on 31 May 2007. It introduced Apache License version 2.0 compatibility (prior versions are incompatible), clarified the role of outside contractors, and made an exception to avoid

864-408: A US federal court ruled that an open-source license is an enforceable contract. In October 2021 SFC sued Vizio over breach of contract as an end user to request source code for Vizio's TVs, a federal judge has ruled in the interim that the GPL is an enforceable contract by end users as well as a license for copyright holders. The text of the GPL is itself copyrighted , and the copyright is held by

972-466: 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, cannot be evolved into, "this is not a biological system at the end of the day, it's a software system." A Linux-based system is a modular Unix-like operating system, deriving much of its basic design from principles established in Unix during

1080-971: A different window manager if preferred. Wayland is a display server protocol intended as a replacement for the X11 protocol; as of 2022 , it has received relatively wide adoption. 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. Additionally, many window managers have been made for Wayland, such as Sway or Hyprland, as well as other graphical utilities such as Waybar or Rofi. Linux currently has two modern kernel-userspace APIs for handling video input devices: V4L2 API for video streams and radio, and DVB API for digital TV reception. Due to

1188-443: A licensee has no right to redistribute it, not even in modified form (barring fair use ), except under the terms of the license. One is only required to adhere to the terms of the GPL if one wishes to exercise rights normally restricted by copyright law, such as redistribution. Conversely, if one distributes copies of the work without abiding by the terms of the GPL (for instance, by keeping the source code secret), they can be sued by

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1296-456: A modified derivative of a GPL licensed content management system is not required to distribute its changes to the underlying software, because the modified web portal is not being redistributed but rather hosted, and also because the web portal output is also not a derivative work of the GPL licensed content management system. There has been debate on whether it is a violation of the GPLv1 to release

1404-404: A place in server installations such as the popular LAMP application stack. The use of Linux distributions in home and enterprise desktops has been growing. Linux distributions have also become popular in the netbook market, with many devices shipping with customized Linux distributions installed, and Google releasing their own ChromeOS designed for netbooks. Linux's greatest success in

1512-450: A popular CLI shell. The graphical user interface (or GUI) used by most Linux systems is built on top of an implementation of the X Window System . More recently, the Linux community has sought to advance to Wayland as the new display server protocol, in place of X11. Many other open-source software projects contribute to Linux systems. Installed components of a Linux system include the following: The user interface , also known as

1620-520: A series of widely used free software licenses , or copyleft licenses, that guarantee end users the freedoms to run, study, share, and modify the software. The GPL was the first copyleft license for general use. It was originally written by Richard Stallman , the founder of the Free Software Foundation (FSF), for the GNU Project . The license grants the recipients of a computer program

1728-481: A significant business around Linux distributions. The free software licenses , 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 symbiotic . One common business model of commercial suppliers is charging for support, especially for business users. A number of companies also offer

1836-404: A single interface productively. This enables the following features : persistence, multiple windows, and session sharing. Screen is often used when a network connection to the terminal is unreliable, as a dropped network connection typically terminates all programs the user was running (child processes of the login session), due to the session ending and sending a "hangup" signal ( SIGHUP ) to all

1944-493: 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 , Apple DOS , and versions of the classic Mac OS before 7.6 freely copyable (but not modifiable). As computer hardware standardized throughout

2052-972: A system's software from one central location. A distribution is largely driven by its developer and user communities. Some vendors develop and fund their distributions on a volunteer basis, Debian being a well-known example. Others maintain a community version of their commercial distributions, as Red Hat does with Fedora , and SUSE does with openSUSE . 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 IRC chatrooms or newsgroups . Online forums are another means of support, with notable examples being Unix & Linux Stack Exchange , LinuxQuestions.org and

2160-402: A user may interact with the application; however, certain extensions of the X Window System are not capable of working over the network. Several X display servers exist, with the reference implementation, X.Org Server , being the most popular. Server distributions might provide a command-line interface for developers and administrators, but provide a custom interface for end-users, designed for

2268-453: 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. Many developers of open-source software agree that the Linux kernel was not designed but rather evolved through natural selection . Torvalds considers that although

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2376-418: Is allowed to charge a fee for this service or do this free of charge. This latter point distinguishes the GPL from software licenses that prohibit commercial redistribution. The FSF argues that free software should not place restrictions on commercial use, and the GPL explicitly states that GPL works may be sold at any price. The GPL additionally states that a distributor may not impose "further restrictions on

2484-477: Is an issue regarding linking: namely, whether a proprietary program that uses a GPL library is in violation of the GPL. Linux This is an accepted version of this page Linux ( / ˈ l ɪ n ʊ k s / , LIN -uuks ) is a family of open-source Unix-like operating systems based on the Linux kernel , an operating system kernel first released on September 17, 1991, by Linus Torvalds . Linux

2592-449: Is applied to ensure that end users retain the freedoms defined above. However, software running as an application program under a GPL-licensed operating system such as Linux is not required to be licensed under GPL or to be distributed with source-code availability—the licensing depends only on the used libraries and software components and not on the underlying platform. For example, if a program consists only of original source code , or

2700-427: Is combined with source code from other software components , then the custom software components need not be licensed under GPL and need not make their source code available; even if the underlying operating system used is licensed under the GPL, applications running on it are not considered derivative works. Only if GPL licensed parts are used in a program (and the program is distributed), then all other source code of

2808-495: Is how the compiled code was available and there are "clear directions" on where to find the source code. The FSF does not hold the copyright for a work released under the GPL unless an author explicitly assigns copyrights to the FSF (which seldom happens except for programs that are part of the GNU project). Only the individual copyright holders have the authority to sue when a license violation

2916-516: Is licensed under the GPLv2, with an exception for system calls that allows code that calls the kernel via system calls not to be licensed under the GPL. Because of the dominance of Linux-based Android on smartphones , Linux, including Android, has the largest installed base of all general-purpose operating systems as of May 2022 . Linux is, as of March 2024 , used by around 4 percent of desktop computers . The Chromebook , which runs

3024-500: Is prohibited by copyright law . The FSF argues that freedom-respecting free software should also not restrict commercial use and distribution (including redistribution): In purely private (or internal) use—with no sales and no distribution—the software code may be modified and parts reused without requiring the source code to be released. For sales or distribution, the entire source code needs to be made available to end users, including any code changes and additions—in that case, copyleft

3132-499: Is suspected. Software under the GPL may be run for all purposes, including commercial purposes and even as a tool for creating proprietary software , such as when using GPL-licensed compilers . Users or companies who distribute GPL-licensed works (e.g. software), may charge a fee for copies or give them free of charge. This distinguishes the GPL from shareware software licenses that allow copying for personal use but prohibit commercial distribution or proprietary licenses where copying

3240-403: 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. Some free and open-source software licenses are based on the principle of 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,

3348-577: Is the Bourne-Again Shell (bash), originally developed for the GNU Project, other shells such as Zsh are also used. 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 . On desktop systems, the most popular user interfaces are

GNU Screen - Misplaced Pages Continue

3456-768: Is typically packaged as a Linux distribution (distro), which includes the kernel and supporting system software and libraries — many of which are provided by the GNU Project — to create a complete operating system. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses and recommends the name " GNU/Linux " to emphasize the use and importance of GNU software in many distributions, causing some controversy . Thousands of distributions exist, many based directly or indirectly on other distributions; popular Linux distributions include Debian , Fedora Linux , Arch Linux , and Ubuntu , while commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise . Other than

3564-468: Is typically built into the firmware and is highly tailored to the system. This includes routers , automation controls, smart home devices , video game consoles , televisions (Samsung and LG smart TVs ), automobiles (Tesla, Audi, Mercedes-Benz, Hyundai, and Toyota), and spacecraft ( Falcon 9 rocket, Dragon crew capsule, and the Ingenuity Mars helicopter). The Unix operating system

3672-415: Is used on a wide variety of devices including PCs, workstations , mainframes and embedded systems . Linux is the predominant operating system for servers and is also used on all of the world's 500 fastest supercomputers . When combined with Android , which is Linux-based and designed for smartphones , they have the largest installed base of all general-purpose operating systems . The Linux kernel

3780-691: The ASP loophole in the GPL . As there were concerns expressed about the administrative costs of checking code for this additional requirement, it was decided to keep the GPL and the AGPL license separated. Others, notably some high-profile Linux kernel developers such as Linus Torvalds , Greg Kroah-Hartman , and Andrew Morton , commented to the mass media and made public statements about their objections to parts of discussion drafts 1 and 2. The kernel developers referred to GPLv3 draft clauses regarding DRM / Tivoization , patents, and "additional restrictions", and warned of

3888-499: The AGPL (v1) , and patent deals between Microsoft and distributors of free and open-source software, which some viewed as an attempt to use patents as a weapon against the free software community. Version 3 was developed as an attempt to address these concerns and was officially released on 29 June 2007. Version 1 of the GNU GPL, released on 25 February 1989, was written to protect against

3996-421: The Free Software Foundation and wrote the GNU General Public License (GNU GPL) in 1989. By the early 1990s, many of the programs required in an operating system (such as libraries, compilers , text editors , a command-line shell , and a windowing system ) were completed, although low-level elements such as device drivers , daemons , and the kernel , called GNU Hurd , were stalled and incomplete. Minix

4104-736: The GNU toolchain , which includes the GNU Compiler Collection (GCC) and the GNU Build System . Amongst others, GCC provides compilers for Ada , C , C++ , Go and Fortran . Many programming languages have a cross-platform reference implementation that supports Linux, for example PHP , Perl , Ruby , Python , Java , Go , Rust and Haskell . First released in 2003, the LLVM project provides an alternative cross-platform open-source compiler for many languages. Proprietary compilers for Linux include

4212-470: The GUI shells , packaged together with extensive Desktop environments , such as KDE Plasma , GNOME , MATE , Cinnamon , LXDE , Pantheon , and 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 and permits a graphical application running on one system to be displayed on another where

4320-481: The Software Freedom Law Center . According to Stallman, the most important changes were in relation to software patents , free software license compatibility, the definition of "source code", and hardware restrictions on software modifications, such as tivoization . Other changes related to internationalization, how license violations are handled, and how additional permissions could be granted by

4428-546: The WIPO Copyright Treaty , and that those who convey the work waive all legal power to prohibit circumvention of the technical protection measure "to the extent such circumvention is effected by exercising rights under this License with respect to the covered work". This means that users cannot be held liable for circumventing DRM implemented using GPLv3-licensed code under laws such as the U.S. Digital Millennium Copyright Act (DMCA). The distribution rights granted by

GNU Screen - Misplaced Pages Continue

4536-476: The 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 windows or on a separate virtual console . CLI shells are text-based user interfaces, which use text for both input and output. The dominant shell used in Linux

4644-399: The 1970s and 1980s. Such a system uses a monolithic kernel , the Linux kernel, which handles process control, networking, access to the peripherals , and file systems . Device drivers are either integrated directly with the kernel or added as modules that are loaded while the system is running. The GNU userland is a key part of most systems based on the Linux kernel, with Android being

4752-451: 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. Most programming languages support Linux either directly or through third-party community based ports . The original development tools used for building both Linux applications and operating system programs are found within

4860-634: The Free Software Foundation. The FSF permits people to create new licenses based on the GPL, as long as the derived licenses do not use the GPL preamble without permission. This is discouraged, however, since such a license might be incompatible with the GPL and causes a perceived license proliferation . Other licenses created by the GNU project include the GNU Lesser General Public License , GNU Free Documentation License , and GNU Affero General Public License . The text of

4968-663: 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. Linux-based distributions are intended by developers for interoperability with other operating systems and established computing standards. Linux systems adhere to POSIX, SUS , LSB , ISO , and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT. Free software projects, although developed through collaboration , are often produced independently of each other. The fact that

5076-404: The GPL for modified versions of the work are not unconditional. When someone distributes a GPL licensed work plus their own modifications, the requirements for distributing the whole work cannot be any greater than the requirements that are in the GPL. This requirement is known as copyleft. It earns its legal power from the use of copyright on software programs. Because a GPL work is copyrighted,

5184-517: The GPL is not itself under the GPL. The license's copyright disallows modification of the license. Copying and distributing the license is allowed since the GPL requires recipients to get "a copy of this License along with the Program". According to the GPL FAQ, anyone can make a new license using a modified version of the GPL as long as they use a different name for the license, do not mention "GNU", and remove

5292-413: The GPL license family has been one of the most popular software licenses in the free and open-source software (FOSS) domain. Prominent free software programs licensed under the GPL include the Linux kernel and the GNU Compiler Collection (GCC). David A. Wheeler argues that the copyleft provided by the GPL was crucial to the success of Linux -based systems, giving the programmers who contributed to

5400-528: The GPL license includes an optional "any later version" clause, allowing users to choose between the original terms or the terms in new versions as updated by the FSF. Software projects licensed with the optional "or later" clause include the GNU Project, while projects like the Linux kernel is licensed under GPLv2 only. The "or any later version" clause is sometimes known as a "lifeboat clause" since it allows combinations between different versions of GPL-licensed software to maintain compatibility. The original GPL

5508-431: The GPL licensed program, they may still use the software within their organization however they like, and works (including programs) constructed by the use of the program are not required to be covered by this license. Software developer Allison Randal argued that the GPLv3 as a license is unnecessarily confusing for lay readers, and could be simplified while retaining the same conditions and legal force. In April 2017,

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5616-412: The GPLv2 license used had the optional "or later" clause and the software was upgraded to GPLv3. While the "GPLv2 or any later version" clause is considered by FSF as the most common form of licensing GPLv2 software, Toybox developer Rob Landley described it as a lifeboat clause . Software projects licensed with the optional "or later" clause include the GNU Project , while a prominent example without

5724-460: The Linux kernel, key components that make up a distribution may include a display server (windowing system) , a package manager , a bootloader and the Bash shell . Linux is one of the most prominent examples of free and open-source software collaboration. While originally developed for x86 based personal computers , it has since been ported to more platforms than any other operating system, and

5832-647: The Linux kernel-based ChromeOS , dominates the US K–12 education market and represents nearly 20 percent of sub-$ 300 notebook sales in the US. Linux is the leading operating system on servers (over 96.4% of the top one million web servers' operating systems are Linux), leads other big iron systems such as mainframe computers , and is used on all of the world's 500 fastest supercomputers (as of November 2017 , having gradually displaced all competitors). Linux also runs on embedded systems , i.e., devices whose operating system

5940-605: The Linux kernel. On July 3, 1991, to implement Unix system calls , Linus Torvalds attempted unsuccessfully to obtain a digital copy of the POSIX standards documentation with a request to the comp.os.minix newsgroup . After not finding the POSIX documentation, Torvalds initially resorted to determining system calls from SunOS documentation owned by the university for use in operating its Sun Microsystems server. He also learned some system calls from Tanenbaum's Minix text. Torvalds began

6048-523: The Software Package Data Exchange (SPDX). The license includes instructions to specify "version 2 of the License, or (at your option) any later version" to allow the flexible optional use of either version 2 or 3, but some developers change this to specify "version 2" only. In late 2005, the Free Software Foundation (FSF) announced work on version 3 of the GPL (GPLv3). On 16 January 2006,

6156-596: The at-the-time novel feature of disconnection/reattachment was added. Around 1990, Laumann handed over maintenance of the code to Jürgen Weigert and Michael Schroeder at the University of Erlangen–Nuremberg , who later moved the project to the GNU Project and added features such as scrollback, split-screen, copy-and-paste , and screen sharing . By 2014, development had slowed to a crawl. Wanting to change this, Amadeusz Sławiński volunteered to help. In response, Laumann granted him maintainership. Sławiński proceeded to put out

6264-466: 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." Bryan Cantrill , an engineer of

6372-631: The child processes. Running the applications under screen means that the session does not terminate – only the now-defunct terminal gets detached – so applications don't even know the terminal has detached, and allows the user to reattach the session later and continue working from where they left off. Screen was originally designed by Oliver Laumann and Carsten Bormann at Technische Universität Berlin and published in 1987. Design criteria included VT100 emulation (including ANSI X3.64 (ISO 6429) and ISO 2022) and reasonable performance for heavy daily use when character-based terminals were still common. Later,

6480-429: The clause is the Linux kernel. The final version of the license text was published on 29 June 2007. The terms and conditions of the GPL must be made available to anybody receiving a copy of a work that has a GPL applied to it ("the licensee"). Any licensee who adheres to the terms and conditions is given permission to modify the work, as well as to copy and redistribute the work or any derivative version. The licensee

6588-447: 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 to the success of having userspace applications to be able to work with all formats supported by those devices. The primary difference between Linux and many other popular contemporary operating systems

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6696-498: The consumer market is perhaps the mobile device market, with Android being the dominant operating system on smartphones and very popular on tablets and, more recently, on wearables . Linux gaming is also on the rise with Valve showing its support for Linux and rolling out SteamOS , its own gaming-oriented Linux distribution, which was later implemented in their Steam Deck platform. Linux distributions have also gained popularity with various local and national governments, such as

6804-470: The copyright holder. The concept of "software propagation", as a term for the copying and duplication of software, was explicitly defined. The public consultation process was coordinated by the Free Software Foundation with assistance from Software Freedom Law Center, Free Software Foundation Europe , and other free software groups. Comments were collected from the public via the gplv3.fsf.org web portal, using purpose-written software called stet . During

6912-464: 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 alpha-particles in DNA ." 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

7020-450: The development of 386BSD , from which NetBSD , OpenBSD and 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. While attending the University of Helsinki in the fall of 1990, Torvalds enrolled in a Unix course. The course used a MicroVAX minicomputer running Ultrix , and one of

7128-477: The development of the Linux kernel on Minix and applications written for Minix were also used on Linux. Later, Linux matured and further Linux kernel development took place on Linux systems. GNU applications also replaced all Minix components, because it was advantageous to use the freely available code from the GNU Project with the fledgling operating system; code licensed under the GNU GPL can be reused in other computer programs as long as they also are released under

7236-476: The development of the components of the system and free software. An analysis of the Linux kernel in 2017 showed that well over 85% of the code was developed by programmers who are being paid for their work, leaving about 8.2% to unpaid developers and 4.1% unclassified. Some of the major corporations that provide contributions include Intel , Samsung , Google , AMD , Oracle , and Facebook . Several corporations, notably Red Hat, Canonical , and SUSE have built

7344-433: The federal government of Brazil . Linus Torvalds is the lead maintainer for the Linux kernel and guides its development, while Greg Kroah-Hartman is the lead maintainer for the stable branch. Zoë Kooyman is the executive director of the Free Software Foundation, which in turn supports the GNU components. Finally, individuals and corporations develop third-party non-GNU components. These third-party components comprise

7452-399: The first "discussion draft" of GPLv3 was published, and the public consultation began. The public consultation was originally planned for nine to fifteen months, but ultimately lasted eighteen months, with four drafts being published. The official GPLv3 was released by the FSF on 29 June 2007. GPLv3 was written by Richard Stallman, with legal counsel from Eben Moglen and Richard Fontana from

7560-476: The first new Screen release in half a decade. Because there were some unofficial "Screen 4.1" releases floating around the Internet, he called this new release "Screen 4.2.0". In May 2015, on openSUSE Conference, Jürgen Weigert invited Alexander Naumov to help to develop and maintain GNU screen. Two months later with Alex's help GNU screen 4.3.0 was released. GNU General Public License The GNU General Public Licenses ( GNU GPL or simply GPL ) are

7668-466: The first version of the Linux kernel on the Internet . Like GNU and 386BSD, Linux did not have any Unix code and therefore avoided any current legal issues . Desktop Linux distributions include a windowing system such as X11 or Wayland and a desktop environment such as GNOME , KDE Plasma or Xfce . Distributions intended for servers may not have a graphical user interface at all or include

7776-416: The kernel assurance that their work would benefit the whole world and remain free, rather than being exploited by software companies that would not have to give anything back to the community. In 2007, the third version of the license (GPLv3) was released to address some perceived problems with the second version (GPLv2) which were discovered during the latter's long-time usage. To keep the license current,

7884-536: The legal distinction between a license and a contract is an important one: contracts are enforceable by contract law , whereas licenses are enforced under copyright law . However, this distinction is not useful in the many jurisdictions where there are no differences between contracts and licenses, such as civil law systems. Those who do not accept the GPL's terms and conditions do not have permission, under copyright law, to copy or distribute GPL-licensed software or derivative works. However, if they do not redistribute

7992-420: The license. Copyleft applies only when a person seeks to redistribute the program. Developers may make private modified versions with no obligation to divulge the modifications, as long as they do not distribute the modified software to anyone else. Copyleft applies only to the software, and not to its output (unless that output is itself a derivative work of the program). For example, a public web portal running

8100-431: The major change in GPLv2 was the "Liberty or Death" clause, as he calls it – Section 7. The section says that licensees may distribute a GPL-covered work only if they can satisfy all of the license's obligations, despite any other legal obligations they might have. In other words, the obligations of the license may not be severed due to conflicting obligations. This provision is intended to discourage any party from using

8208-516: The mid-1990s in the supercomputing community, where organizations such as NASA started to replace their increasingly expensive machines with clusters of inexpensive commodity computers running Linux. Commercial use began when Dell and IBM , followed by Hewlett-Packard , started offering Linux support to escape Microsoft 's monopoly in the desktop operating system market. Today, Linux systems are used throughout computing, from embedded systems to virtually all supercomputers , and have secured

8316-441: The notable exception. The 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 toolchain is a broad collection of programming tools vital to Linux development (including the compilers used to build the Linux kernel itself), and the coreutils implement many basic Unix tools . The GNU Project also develops Bash ,

8424-501: 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 apt , yum , zypper , pacman or portage to install, remove, and update all of

8532-453: The original author under copyright law. Copyright law has historically been used to prevent distribution of work by parties not authorized by the creator. Copyleft uses the same copyright laws to accomplish a very different goal. It grants rights to distribution to all parties insofar as they provide the same rights to subsequent ones, and they to the next, etc. In this way, the GPL and other copyleft licenses attempt to enforce libre access to

8640-509: The parties who would receive the covered work from you, a discriminatory patent license   ... This aimed to make such future deals ineffective. The license was also meant to cause Microsoft to extend the patent licenses it granted to Novell customers for the use of GPLv3 software to all users of that GPLv3 software; this was possible only if Microsoft was legally a "conveyor" of the GPLv3 software. Early drafts of GPLv3 also let licensors add an AGPL -like requirement that would have plugged

8748-452: The perceived problems of a Microsoft–Novell style agreement, saying in Section 11 paragraph 6 that: You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of

8856-409: The preamble, though the preamble can be used in a modified license if permission to use it is obtained from the Free Software Foundation (FSF). According to the FSF, "The GPL does not require you to release your modified version or any part of it. You are free to make modifications and use them privately, without ever releasing them." However, if one releases a GPL-licensed entity to the public, there

8964-522: The program needs to be made available under the same license terms. The GNU Lesser General Public License (LGPL) was created to have a weaker copyleft than the GPL, in that it does not require custom-developed source code (distinct from the LGPL licensed parts) to be made available under the same license terms. The fifth section of version 3 states that no GPL-licensed code shall be considered an effective "technical protection measure" as defined by Article 11 of

9072-420: The public consultation process, 962 comments were submitted for the first draft. By the end of the comment period, a total of 2,636 comments had been submitted. The third draft was released on 28 March 2007. This draft included language intended to prevent patent-related agreements such as the controversial Microsoft-Novell patent agreement , and restricted the anti-tivoization clauses to a legal definition of

9180-455: The required texts was Operating Systems: Design and Implementation by Andrew S. Tanenbaum . This textbook included a copy of Tanenbaum's Minix operating system. It was with this course that Torvalds first became exposed to Unix. In 1991, he became curious about operating systems. Frustrated by the licensing of Minix, which at the time limited it to educational use only, he began to work on his operating system kernel, which eventually became

9288-426: The rights granted by the GPL". This forbids activities such as distributing the software under a non-disclosure agreement or contract. The fourth section for version 2 of the license and the seventh section of version 3 require that programs distributed as pre-compiled binaries be accompanied by a copy of the source code, a written offer to distribute the source code via the same mechanism as the pre-compiled binary, or

9396-544: The rights of the Free Software Definition . The licenses in the GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms. It is more restrictive than the Lesser General Public License and even further distinct from the more widely-used permissive software licenses such as BSD , MIT , and Apache . Historically,

9504-412: The same or a compatible license. Torvalds initiated a switch from his original license, which prohibited commercial redistribution, to the GNU GPL. Developers worked to integrate GNU components with the Linux kernel, creating a fully functional and free operating system. Linus Torvalds had wanted to call his invention " Freax ", a portmanteau of "free", "freak", and "x" (as an allusion to Unix). During

9612-441: 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

9720-440: The source code in obfuscated form, such as in cases in which the author is less willing to make the source code available. The consensus was that while unethical, it was not considered a violation. The issue was clarified when the license was altered with v2 to require that the "preferred" version of the source code be made available. The GPL was designed as a license , rather than a contract. In some common law jurisdictions,

9828-569: The start of his work on the system, some of the project's makefiles included the name "Freax" for about half a year. Initially, Torvalds considered the name "Linux" but dismissed it as too egotistical. To facilitate development, the files were uploaded to the FTP server ( ftp.funet.fi ) of FUNET in September 1991. Ari Lemmke, Torvalds' coworker at the Helsinki University of Technology (HUT) who

9936-417: The terms of GPLv1 could be combined with software under more permissive terms, as this would not change the terms under which the whole could be distributed. However, software distributed under GPLv1 could not be combined with software distributed under a more restrictive license, as this would conflict with the requirement that the whole be distributable under the terms of GPLv1. According to Richard Stallman,

10044-446: The two main methods by which software distributors restricted the freedoms that define free software. The first problem was that distributors might publish only binary files that are executable, but not readable or modifiable by humans. To prevent this, GPLv1 stated that copying and distributing copies of any portion of the program must also make the human-readable source code available under the same licensing terms. The second problem

10152-471: 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 managers exist for X11, including tiling , dynamic , stacking , and 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 managers such as dwm , ratpoison , or i3wm provide

10260-559: The various distribution-specific support and community forums, such as ones for Ubuntu , Fedora, Arch Linux , Gentoo , etc. Linux distributions host mailing lists ; 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. Although Linux distributions are generally available without charge, several large corporations sell, support, and contribute to

10368-429: The word "Linux" should be pronounced, he included an audio guide with the kernel source code. However, in this recording, he pronounces Linux as /ˈlinʊks/ ( LEEN -uuks ) with a short but close front unrounded vowel , instead of a near-close near-front unrounded vowel as in his newsgroup post. The adoption of Linux in production environments, rather than being used only by hobbyists, started to take off first in

10476-459: The work and all derivatives. Many distributors of GPL licensed programs bundle the source code with the executables . An alternative method of satisfying the copyleft is to provide a written offer to provide the source code on a physical medium (such as a CD) upon request. In practice, many GPL licensed programs are distributed over the Internet, and the source code is made available over FTP or HTTP . For Internet distribution, this complies with

10584-510: The written offer to obtain the source code that the user got when they received the pre-compiled binary under the GPL. The second section of version 2 and the fifth section of version 3 also require giving "all recipients a copy of this License along with the Program". Version 3 of the license allows making the source code available in additional ways in fulfillment of the seventh section. These include downloading source code from an adjacent network server or by peer-to-peer transmission, provided that

10692-501: Was conceived and implemented in 1969, at AT&T 's Bell Labs , in the United States by Ken Thompson , Dennis Ritchie , Douglas McIlroy , and Joe Ossanna . First released in 1971, Unix was written entirely in assembly language , as was common practice at the time. In 1973, in a key pioneering approach, it was rewritten in the C programming language by Dennis Ritchie (except for some hardware and I/O routines). The availability of

10800-494: Was created by Andrew S. Tanenbaum , a computer science professor, and released in 1987 as a minimal Unix-like operating system targeted at students and others who wanted to learn operating system principles. Although the complete source code of Minix was freely available, the licensing terms prevented it from being free software until the licensing changed in April 2000. Although not released until 1992, due to legal complications ,

10908-510: Was designed by Linus Torvalds , following the lack of a working kernel for GNU , a Unix -compatible operating system made entirely of free software that had been undergoing development since 1983 by Richard Stallman . While a separate working Unix-compatible system called Minix was later released, its license was not entirely free at the time. The first entirely free Unix for personal computers, 386BSD , did not appear until 1992, by which time Torvalds had already built and publicly released

11016-439: Was introduced at the same time and numbered with version 2 to show that both were complementary. The version numbers diverged in 1999 when version 2.1 of the LGPL was released, which renamed it the GNU Lesser General Public License to reflect its place in the philosophy. The GPLv2 was also modified to refer to the new name of the LGPL, but its version number remained the same, resulting in the original GPLv2 not being recognised by

11124-459: Was later originally developed, it represented the first successful commercial attempt at distributing a primarily single-user microcomputer that ran a Unix operating system. With Unix increasingly "locked in" as a proprietary product, the GNU Project , started in 1983 by Richard Stallman , had the goal of creating a "complete Unix-compatible software system" composed entirely of free software . Work began in 1984. Later, in 1985, Stallman started

11232-510: 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. Later, however, Torvalds consented to "Linux". According to a newsgroup post by Torvalds, the word "Linux" should be pronounced ( / ˈ l ɪ n ʊ k s / LIN -uuks ) with a short 'i' as in 'print' and 'u' as in 'put'. To further demonstrate how

11340-518: Was released from its obligation not to enter the computer business; freed of that obligation, Bell Labs began selling Unix as a proprietary product, where users were not legally allowed to modify it. Onyx Systems began selling early microcomputer-based Unix workstations in 1980. Later, Sun Microsystems , founded as a spin-off of a student project at Stanford University , also began selling Unix-based desktop workstations in 1982. While Sun workstations did not use commodity PC hardware, for which Linux

11448-426: Was that distributors might add restrictions, either to the license or by combining the software with other software that had other restrictions on distribution. The union of two sets of restrictions would apply to the combined work, thus adding unacceptable constrictions. To prevent this, GPLv1 stated that modified versions, as a whole, had to be distributed under the terms of GPLv1. Therefore, software distributed under

11556-594: Was to produce one license that could be used for any project, thus making it possible for many projects to share code. The second version of the license, version 2, was released in 1991. Over the following 15 years, members of the free software community became concerned over problems in the GPLv2 license that could let someone exploit GPL-licensed software in ways contrary to the license's intent. These problems included tivoization (the inclusion of GPL-licensed software in hardware that refuses to run modified versions of its software), compatibility issues similar to those of

11664-474: Was written by Richard Stallman in 1989, for use with programs released as part of the GNU project. It was based on a unification of similar licenses used for early versions of GNU Emacs (1985), the GNU Debugger , and the GNU C Compiler . These licenses contained similar provisions to the modern GPL, but were specific to each program, rendering them incompatible, despite being the same license. Stallman's goal

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