Linux (pronounced /ˈlɪnəks/ lin-əks or, less frequently, /ˈlaɪnəks/ lyn-əks) is a Unix-like and mostly POSIX-compliant computer operating system (OS) assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on October 5, 1991 by Linus Torvalds. The Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy.
Linux was originally developed as a free operating system for personal computers based on the Intel x86 architecture, but has since been ported to more computer hardware platforms than any other operating system. Because of the dominance of Android on smartphones, Linux has the largest installed base of all general-purpose operating systems. Linux is also the leading operating system on servers and other big iron systems such as mainframe computers and virtually all fastest supercomputers, but is used on only around 2.3% of desktop computers when not includingChrome OS, which has about 5% of the overall and nearly 20% of the sub-$300 notebook sales. Linux also runs on embedded systems, which are devices whose operating system is typically built into the firmware and is highly tailored to the system; this includes smartphones and tablet computers running Android and other Linux derivatives, TiVo and similar DVR devices, network routers, facility automation controls, televisions, video game consoles and smartwatches.
The development of Linux is one of the most prominent examples of free and open-source software collaboration. The underlying source code may be used, modified and distributed —
Distributions oriented toward desktop use typically include a windowing system, such as X11, Mir or a Wayland implementation, and an accompanying desktop environment such as GNOME or the KDE Software Compilation; some distributions may also include a less resource-intensive desktop, such as LXDE or Xfce. Distributions intended to run on servers may omit all graphical environments from the standard install, and instead include other software to set up and operate a solution stack such as LAMP. Because Linux is freely redistributable, anyone may create a distribution for any intended use.
History of Linux
The history of Linux began in 1991 with the commencement of a personal project by Finnish student Linus Torvalds to create a new free operating system kernel. Since then, the resulting Linux kernel has been marked by constant growth throughout its history. Since the initial release of its source code in 1991, it has grown from a small number of C files under a license prohibiting commercial distribution to the 4.2.3 version in 2015 with more than 18 million lines of source code under the GNU General Public License v2
Events leading to creation
After AT&T had dropped out of the Multics project, the Unix operating system was conceived and implemented by Ken Thompson and Dennis Ritchie (both of AT&T Bell Laboratories) in 1969 and first released in 1970. Later they rewrote it in a new programming language, C, to make it portable. The availability and portability of Unix caused it to be widely adopted, copied and modified by academic institutions and businesses.
In 1977, the Berkeley Software Distribution (BSD) was developed by the Computer Systems Research Group (CSRG) from UC Berkeley, based on the 6th edition of Unix from AT&T. Since BSD contained Unix code that AT&T owned, AT&T filed a lawsuit (USL v. BSDi) in the early 1990s against the University of California. This strongly limited the development and adoption of BSD.
In 1983, Richard Stallman started the GNU project with the goal of creating a free UNIX-like operating system. As part of this work, he wrote the GNU General Public License (GPL). By the early 1990s, there was almost enough available software to create a full operating system. However, the GNU kernel, called Hurd, failed to attract enough development effort, leaving GNU incomplete.
In 1985, Intel released the 80386, the first x86 microprocessor with a 32-bit instruction set and a memory management unit with paging.
These factors and the lack of a widely adopted, free kernel provided the impetus for Torvalds' starting his project. He has stated that if either the GNU Hurd or 386 BSD kernels had been available at the time, he likely would not have written his own.
The creation of Linux
In 1991, in Helsinki, Linus Torvalds began a project that later became the Linux kernel. He wrote the program specifically for the hardware he was using and independent of an operating system because he wanted to use the functions of his new PC with an 80386 processor. Development was done on MINIX using the GNU C compiler. The GNU C Compiler is still the main choice for compiling Linux today. The code however, can be built with other compilers, such as the Intel C Compiler.
As Torvalds wrote in his book Just for Fun, he eventually ended up writing an operating system kernel. On 25 August 1991, he (at age 21) announced this system in a Usenet posting to the newsgroup "comp.os.minix.":
Hello everybody out there using minix -
I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things).
I've currently ported bash(1.08) and gcc(1.40), and things seem to work. This implies that I'll get something practical within a few months, and I'd like to know what features most people would want. Any suggestions are welcome, but I won't promise I'll implement them 🙂
PS. Yes - it's free of any minix code, and it has a multi-threaded fs. It is NOT portable (uses 386 task switching etc), and it probably never will support anything other than AT-harddisks, as that's all I have :-(.— Linus Torvalds
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, he stored the files under the name "Freax" for about half of a year. Torvalds had already considered the name "Linux," but initially dismissed it as too egotistical.
In order 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 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".
Linux under the GNU GPL
Torvalds first published the Linux kernel under its own licence, which had a restriction on commercial activity.
The software to use with the kernel was software developed as part of the GNU project licensed under the GNU General Public License, a free software license. The first release of the Linux kernel, Linux 0.01, included a binary of GNU's Bash shell.
In the "Notes for linux release 0.01", Torvalds lists the GNU software that is required to run Linux:
Sadly, a kernel by itself gets you nowhere. To get a working system you need a shell, compilers, a library etc. These are separate parts and may be under a stricter (or even looser) copyright. Most of the tools used with linux are GNU software and are under the GNU copyleft. These tools aren't in the distribution - ask me (or GNU) for more info.
In 1992, he suggested releasing the kernel under the GNU General Public License. He first announced this decision in the release notes of version 0.12. In the middle of December 1992 he published version 0.99 using the GNU GPL. Linux and GNU developers worked to integrate GNU components with Linux to make a fully functional and free operating system. Torvalds has stated, "making Linux GPL'd was definitely the best thing I ever did."
Around 2000 Torvalds clarified that the used license for the linux kernel is exactly the GPLv2, without the common "or later clause".
In 2007, after years of draft discussions, the GPLv3 was released and Torvalds and the majority of kernel developers decided against adopting the new license for the linux kernel.
GNU/Linux naming controversy
The designation "Linux" was initially used by Torvalds only for the Linux kernel. The kernel was, however, frequently used together with other software, especially that of the GNU project. This quickly became the most popular adoption of GNU software. In June 1994 in GNU's bulletin, Linux was referred to as a "free UNIX clone", and the Debian project began calling its product Debian GNU/Linux. In May 1996, Richard Stallman published the editor Emacs 19.31, in which the type of system was renamed from Linux to Lignux. This spelling was intended to refer specifically to the combination of GNU and Linux, but this was soon abandoned in favor of "GNU/Linux".
This name garnered varying reactions. The GNU and Debian projects use the name, although most people simply use the term "Linux" to refer to the combination.
Torvalds announced in 1996 that there would be a mascot for Linux, a penguin. This was due to the fact when they were about to select the mascot, Torvalds did mention he was bitten by a little penguin (Eudyptula minor) on a visit to the National Zoo & Aquarium in Canberra, Australia. Larry Ewing provided the original draft of today's well known mascot based on this description. The name Tux was suggested by James Hughes as derivative of Torvalds' UniX.
The largest part of the work on Linux is performed by the community: the thousands of programmers around the world that use Linux and send their suggested improvements to the maintainers. Various companies have also helped not only with the development of the kernels, but also with the writing of the body of auxiliary software, which is distributed with Linux. As of February 2015, over 80% of Linux kernel developers are paid.
It is released both by organized projects such as Debian, and by projects connected directly with companies such as Fedora and openSUSE. The members of the respective projects meet at various conferences and fairs, in order to exchange ideas. One of the largest of these fairs is the LinuxTag in Germany (currently in Berlin), where about 10,000 people assemble annually, in order to discuss Linux and the projects associated with it.
Open Source Development Lab and Linux Foundation
The Open Source Development Lab (OSDL) was created in the year 2000, and is an independent nonprofit organization which pursues the goal of optimizing Linux for employment in data centers and in the carrier range. It served as sponsored working premises for Linus Torvalds and also for Andrew Morton (until the middle of 2006 when Morton transferred to Google). Torvalds worked full-time on behalf of OSDL, developing the Linux kernels.
On 22 January 2007, OSDL and the Free Standards Group merged to form The Linux Foundation, narrowing their respective focuses to that of promoting GNU/Linux in competition with Microsoft Windows. As of 2015, Torvalds remains with the Linux Foundation as a Fellow.
CompaniesDespite being freely available, companies profit from Linux. These companies, many of which are also members of the Linux Foundation, invest substantial resources into the advancement and development of Linux, in order to make it suited for various application areas. This includes hardware donations for driver developers, cash donations for people who develop Linux software, and the employment of Linux programmers at the company. Some examples are Dell, IBM and Hewlett-Packard, which validate, use and sell Linux on their own servers, and Red Hat and SUSE, which maintain their own enterprise distributions. Likewise, Digia supports Linux by the development and LGPL licensing of Qt, which makes the development of KDE possible, and by employing some of the X and KDE developers.
KDE was the first advanced desktop environment, but it was controversial due to the then-proprietary Qt toolkit used. GNOME was developed as an alternative due to licensing questions. The two use a different underlying toolkit and thus involve different programming, and are sponsored by two different groups, German nonprofit KDE e.V. and the United States nonprofit GNOME Foundation.
As of April 2007, one journalist estimated that KDE had 65% of market share versus 26% for GNOME. In January 2008, KDE 4 was released prematurely with bugs, driving some users to GNOME. GNOME 3, released in April 2011, was called an "unholy mess" by Linus Torvalds due to its controversial design changes.
Dissatisfaction with GNOME 3 led to a fork, Cinnamon, which is developed primarily by Linux Mint developer Clement LeFebvre. This restores the more traditional desktop environment with marginal improvements.
The relatively well-funded distribution, Ubuntu, designed (and released in June 2011) another user interface called Unity which is radically different from the conventional desktop environment and has been criticized as having various flaws and lacking configurability. The motivation was a single desktop environment for desktops and tablets, although as of November 2012 Unity has yet to be used widely in tablets. However, the smartphone and tablet version of Ubuntu and its Unity interface was unveiled by Canonical Ltd in January 2013.
"Linux is obsolete"
In 1992, Andrew S. Tanenbaum, recognized computer scientist and author of the Minix microkernel system, wrote a Usenet article on the newsgroup comp.os.minix with the title "Linux is obsolete", which marked the beginning of a famous debate about the structure of the then-recent Linux kernel. Among the most significant criticisms were that:
- The kernel was monolithic and thus old-fashioned.
- The lack of portability, due to the use of exclusive features of the Intel 386 processor. "Writing a new operating system that is closely tied to any particular piece of hardware, especially a weird one like the Intel line, is basically wrong."
- There was no strict control of the source code by any individual person.
- Linux employed a set of features which were useless (Tanenbaum believed that multithreaded file systems were simply a "performance hack").
Tanenbaum's prediction that Linux would become outdated within a few years and replaced by GNU Hurd (which he considered to be more modern) proved incorrect. Linux has been ported to all major platforms and its open development model has led to an exemplary pace of development. In contrast, GNU Hurd has not yet reached the level of stability that would allow it to be used on a production server. His dismissal of the Intel line of 386 processors as 'weird' has also proven short-sighted, as the x86 series of processors and the Intel Corporation would later become near ubiquitous in personal computers and servers.
Competition from MicrosoftAlthough Torvalds has said that Microsoft's feeling threatened by Linux in the past was of no consequence to him, the Microsoft and Linux camps had a number of antagonistic interactions between 1997 and 2001. This became quite clear for the first time in 1998, when the first Halloween document was brought to light by Eric S. Raymond. This was a short essay by a Microsoft developer that sought to lay out the threats posed to Microsoft by free software and identified strategies to counter these perceived threats.
Competition entered a new phase in the beginning of 2004, when Microsoft published results from customer case studies evaluating the use of Windows vs. Linux under the name “Get the Facts” on its own web page. Based on inquiries, research analysts, and some Microsoft sponsored investigations, the case studies claimed that enterprise use of Linux on servers compared unfavorably to the use of Windows in terms of reliability, security, and total cost of ownership.
In response, commercial Linux distributors produced their own studies, surveys and testimonials to counter Microsoft's campaign. Novell's web-based campaign at the end of 2004 was entitled “Unbending the truth” and sought to outline the advantages as well as dispelling the widely publicized legal liabilities of Linux deployment (particularly in light of the SCO v IBM case). Novell particularly referenced the Microsoft studies in many points. IBM also published a series of studies under the title “The Linux at IBM competitive advantage” to again parry Microsoft's campaign. Red Hat had a campaign called “Truth Happens” aimed at letting the performance of the product speak for itself, rather than advertising the product by studies.
In the autumn of 2006, Novell and Microsoft announced an agreement to co-operate on software interoperability and patent protection. This included an agreement that customers of either Novell or Microsoft may not be sued by the other company for patent infringement. This patent protection was also expanded to non-commercial free software developers. The last part was criticized because it only included non-commercial free software developers.
In July 2009, Microsoft submitted 22,000 lines of source code to the Linux kernel under the GPLV2 license, which were subsequently accepted. Although this has been referred to as "a historic move" and as a possible bell wether of an improvement in Microsoft's corporate attitudes toward Linux and open-source software, the decision was not altogether altruistic, as it promised to lead to significant competitive advantages for Microsoft and avoided legal action against Microsoft. Microsoft was actually compelled to make the code contribution when Vyatta principal engineer and Linux contributor Stephen Hemminger discovered that Microsoft had incorporated a Hyper-V network driver, with GPL-licensed open source components, statically linked to closed-source binaries in contravention of the GPL licence. Microsoft contributed the drivers to rectify the licence violation, although the company attempted to portray it as a charitable act, rather than one to avoid legal action against it. In the past Microsoft had termed Linux a "cancer" and "communist".
By 2011, Microsoft had become the 17th largest contributor to the Linux kernel. As of February 2015, Microsoft was no longer among the top 30 contributing sponsor companies.
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