Linux is a family of free and open-source software operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is packaged in a Linux distribution. Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian and Ubuntu. Commercial distributions include SUSE Linux Enterprise Server. Desktop Linux distributions include a windowing system such as X11 or Wayland, a desktop environment such as GNOME or KDE Plasma. Distributions intended for servers may omit graphics altogether, include a solution stack such as LAMP; because Linux is redistributable, anyone may create a distribution for any purpose. Linux was developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system.
Linux is the leading operating system on servers and other big iron systems such as mainframe computers, the only OS used on TOP500 supercomputers. It is used by around 2.3 percent of desktop computers. The Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20 percent of sub-$300 notebook sales in the US. Linux runs on embedded systems, i.e. devices whose operating system is built into the firmware and is tailored to the system. This includes routers, automation controls, digital video recorders, video game consoles, smartwatches. Many smartphones and tablet computers run other Linux derivatives; because of the dominance of Android on smartphones, Linux has the largest installed base of all general-purpose operating systems. Linux is one of the most prominent examples of open-source software collaboration; the source code may be used and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License.
The Unix operating system was conceived and implemented in 1969, at AT&T's Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, Joe Ossanna. First released in 1971, Unix was written in assembly language, as was common practice at the time. In a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie; the availability of 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 was required to license the operating system's source code to anyone who asked; as a result, Unix grew and became adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs; the GNU Project, started in 1983 by Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed of free software. Work began in 1984. In 1985, Stallman started the Free Software Foundation and wrote the GNU General Public License in 1989.
By the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers and the kernel, called GNU/Hurd, were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, he would not have decided to write his own. Although not released until 1992, due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has stated that if 386BSD had been available at the time, he would not have created Linux. MINIX was created by Andrew S. Tanenbaum, a computer science professor, released in 1987 as a minimal Unix-like operating system targeted at students and others who wanted to learn the operating system principles. Although the complete source code of MINIX was available, the licensing terms prevented it from being free software until the licensing changed in April 2000. In 1991, while attending the University of Helsinki, Torvalds 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 own operating system kernel, which became the Linux kernel. Torvalds began the development of the Linux kernel on MINIX and applications written for MINIX were used on Linux. Linux matured and further Linux kernel development took place on Linux systems. GNU applications replaced all MINIX components, because it was advantageous to use the available code from the GNU Project with the fledgling operating system. 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, making a functional and free operating system. Linus Torvalds had wanted to call his invention "Freax", a portmant
GIMP is a free and open-source raster graphics editor used for image retouching and editing, free-form drawing, converting between different image formats, more specialized tasks. GIMP is released under GPLv3+ licenses and is available for Linux, macOS, Microsoft Windows. GIMP was released as the General Image Manipulation Program. In 1995 Spencer Kimball and Peter Mattis began developing GIMP as a semester-long project at the University of California, Berkeley for the eXperimental Computing Facility. In 1996 GIMP was released as the first publicly available release. In the following year Richard Stallman visited UC Berkeley where Spencer Kimball and Peter Mattis asked if they could change General to GNU. Richard Stallman approved and the definition of the acronym GIMP was changed to be the GNU Image Manipulation Program; this reflected its new existence as being developed as Free Software as a part of the GNU Project. The number of computer architectures and operating systems supported has expanded since its first release.
The first release supported UNIX systems, such as Linux, SGI IRIX and HP-UX. Since the initial release, GIMP has been ported to many operating systems, including Microsoft Windows and macOS. Following the first release, GIMP was adopted and a community of contributors formed; the community began developing tutorials and shared better work-flows and techniques. A GUI toolkit called GTK was developed to facilitate the development of GIMP. GTK was replaced by its successor GTK+ after being redesigned using object-oriented programming techniques; the development of GTK+ has been attributed to Peter Mattis becoming disenchanted with the Motif toolkit GIMP used. GIMP is developed by volunteers as a free software project associated with both the GNU and GNOME Projects. Development takes place in a public git source code repository, on public mailing lists and in public chat channels on the GIMPNET IRC network. New features are held in public separate source code branches and merged into the main branch when the GIMP team is sure they won't damage existing functions.
Sometimes this means that features that appear complete do not get merged or take months or years before they become available in GIMP. GIMP itself is released as source code. After a source code release installers and packages are made for different operating systems by parties who might not be in contact with the maintainers of GIMP; the version number used in GIMP is expressed in a major-minor-micro format, with each number carrying a specific meaning: the first number is incremented only for major developments. The second number is incremented with each release of new features, with odd numbers reserved for in-progress development versions and numbers assigned to stable releases; each year GIMP applies for several positions in the Google Summer of Code. From 2006 to 2009 there have been nine GSoC projects that have been listed as successful, although not all successful projects have been merged into GIMP immediately; the healing brush and perspective clone tools and Ruby bindings were created as part of the 2006 GSoC and can be used in version 2.8.0 of GIMP, although there were three other projects that were completed and are available in a stable version of GIMP.
Several of the GSoC projects were completed in 2008, but have been merged into a stable GIMP release in 2009 to 2014 for Version 2.8.xx and 2.9.x. Some of them needed some more code work for the master tree. Second public Development 2.9-Version was 2.9.4 with many deep improvements after initial Public Version 2.9.2 Third Public 2.9-Development version is Version 2.9.6. One of the new features is removing the 4GB size limit of XCF file. Increase of possible threads to 64 is an important point for modern parallel execution in actual AMD Ryzen and Intel Xeon processors. Version 2.9.8 included many bug improvements in gradients and clips. Improvements in performance and optimization beyond bug hunting were the development targets for 2.10.0. MacOS Beta is available with Version 2.10.4 The next stable version in the roadmap is 3.0 with a GTK3 port. The user interface of GIMP is designed by a dedicated usability team; this team was formed. A user interface brainstorming group has since been created for GIMP, where users of GIMP can send in their suggestions as to how they think the GIMP user interface could be improved.
GIMP is presented in two forms and multiple window mode. In multiple-window mode a set of windows contains all GIMP's functionality. By default and tool settings are on the left and other dialogues are on the right. A layers tab is to the right of the tools tab, allows a user to work individually on separate image layers. Layers can be edited by right-clicking on a particular layer to bring up edit options for that layer; the tools tab and layers tab are the most common dockable tabs. The Libre Graphics Meeting (L
The Tanenbaum–Torvalds debate was a debate between Andrew S. Tanenbaum and Linus Torvalds, regarding the Linux kernel and kernel architecture in general. Tanenbaum began the debate in 1992 on the Usenet discussion group comp.os.minix, arguing that microkernels are superior to monolithic kernels and therefore Linux was in 1992, obsolete. Linux kernel developers Peter MacDonald, David S. Miller and Theodore Ts'o joined the debate; the debate has sometimes been considered a flame war. While the debate started out as moderate, with both parties involved making only banal statements about kernel design, it grew progressively more detailed and sophisticated with every round of posts. Besides just kernel design, the debate branched into several other topics, such as which microprocessor architecture would win out over others in the future. Besides Tanenbaum and Torvalds, several other people joined the debate, including Peter MacDonald, an early Linux kernel developer and creator of one of the first distributions, Softlanding Linux System.
The debate opened on January 29, 1992, when Tanenbaum first posted his criticism on the Linux kernel to comp.os.minix, noting how the monolithic design was detrimental to its abilities, in a post titled "LINUX is obsolete". While he did not go into great technical detail to explain why he felt that the microkernel design was better, he did suggest that it was related to portability, arguing that the Linux kernel was too tied to the x86 line of processors to be of any use in the future, as this architecture would be superseded by then. To put things into perspective, he mentioned how writing a monolithic kernel in 1991 is "a giant step back into the 1970s". Since the criticism was posted in a public newsgroup, Torvalds was able to respond to it directly, he did so a day arguing that MINIX has inherent design flaws, while acknowledging that he finds the microkernel kernel design to be superior "from a theoretical and aesthetical" point of view. He claimed that since he was developing the Linux kernel in his spare time and giving it away for free, Tanenbaum should not object to his efforts.
Furthermore, he mentioned how he developed Linux for the Intel 80386 because it was intended as a learning exercise for Torvalds himself. For this reason, he stated, "linux is more portable than minix." Following Linus' reply, Tanenbaum argued that the limitations of MINIX relate to him being a professor, stating the requirement for the system to be able to run on the rather limited hardware of the average student, which he noted was an Intel 8088-based computer, sometimes without a hard drive. Linux was, at that time built for the Intel 386, a more powerful processor. Tanenbaum specifically states "... as of about 1 year ago, there were two versions, one for the PC and one for the 286/386. The PC version was outselling the 286/386 version by 2 to 1." He noted that though Linux was free, it wouldn't be a viable choice for his students, as they would not be able to afford the expensive hardware required to run it, that MINIX could be used on "a regular 4.77 MHz PC with no hard disk." To this, Kevin Brown, another user of the Usenet group, replied that Tanenbaum should not complain about Linux's ties to the 386 architecture, as it was the result of a conscious choice rather than lack of knowledge about operating system design, stating "... an explicit design goal of Linux was to take advantage of the special features of the 386 architecture.
So what is your point? Different design goals get you different designs." He stated that designing a system for cheap hardware would cause it to have portability problems in the future. Despite the fact that MINIX did not support the newer hardware, Tanenbaum argued that since the x86 architecture would be outdone by other architecture designs in the future, he did not need to address the issue, noting "Of course 5 years from now that will be different, but 5 years from now everyone will be running free GNU on their 200 MIPS, 64M SPARCstation-5." He stated that the Linux kernel would fall out of style as hardware progressed, due to it being so tied to the 386 architecture. Torvalds attempted to end the discussion at that point, stating that he felt he should not have overreacted to Tanenbaum's initial statements, that he was composing a personal e-mail to him to apologize. However, he would continue the debate at a time. Despite this debate and Tanenbaum appear to be on good speaking terms; when the issue and full initial debate were published in the O'Reilly Media book Open Sources: Voices from the Open Source Revolution in 1999, it stated that the debate exemplified "the way the world was thinking about OS design at the time".
The 386 processor was the most widespread chip "by several times", according to participant Kevin Brown, with the 486 used in high-end computers, the 286 obsolete, the World Wide Web not yet used. One of Tanenbaum's arguments against Linux was that it was too tied to the x86 architecture and instructi
Linux user group
A Linux User Group or Linux Users' Group or GNU/Linux User Group is a private non-profit or not-for-profit organization that provides support and/or education for Linux users for inexperienced users. The term refers to local groups that meet in person, but is used to refer to online support groups that may have members spread over a wide area and that do not organize, or are not dependent on, physical meetings. Many LUGs encompass FreeBSD and other free-software / open source Unix-based operating systems. Local Linux user groups meet to provide support and/or arrange and host presentations for Linux users for inexperienced users. Given that Linux is not dominated by any specific corporate or institutional entity, LUG meetings encompass a broader range of topics than do the meetings of other user groups. Linux is predominantly user-supported, some support is vastly easier via telephone or in person than over e-mail or USENET. LUGs are still focused on hobbyist users and professionals who are engaged in self-directed study.
SVLUG is among the largest LUGs. It was formed as a Special Interest Group for the Silicon Valley Computer Society, founded by Daniel Kionka to support Xenix and "low-cost PC UNIX systems". According to the Linux User Group HOWTO: Computer user groups are not new. In fact, they were central to the personal computer's history: Microcomputers arose in large part to satisfy demand for affordable, personal access to computing resources from electronics, ham radio, other hobbyist user groups. Giants like IBM discovered the PC to be a good and profitable thing, but initial impetus came from the grassroots. To give just one indication of how LUGs differ from traditional user groups: Traditional groups must monitor what software users redistribute at meetings. While illegal copying of restricted proprietary software occurred, it was discouraged—for good reason. At LUG meetings, that entire mindset does not apply: Far from being forbidden, unrestricted copying of Linux should be among a LUG's primary goals.
In fact, there is anecdotal evidence of traditional user groups having difficulty adapting to Linux's ability to be lawfully copied at will. LUGs meet once per month, in facilities provided by universities, community centers, private corporations, or banquet rooms in restaurants. For example, Silicon Valley's SVLUG met for about 10 years in the back of a Carl's Jr. restaurant, has met for the last several years in meeting rooms at Cisco Systems and, more Symantec. BALUG met for many years in the banquet room above the Four Seas Restaurant in San Francisco's Chinatown. Most LUGs are free, requiring no annual dues. In many cases, the participants are encouraged to patronize the host venues; some LUGs are round table discussions. Some provide formal presentations. For example, Linus Torvalds has talked to SVLUG or BALUG, Hans Reiser presented his early design plans at an SVLUG meeting. Presenters might be anyone in the community with something interesting to say. Corporations will sponsor or encourage their employees to speak at user groups to promote their products.
LUGs require that these presentations provide technically interesting content, rather than overt sales pitches. LUG meetings provide an opportunity for members and guests to make announcements for jobs offered and/or wanted, pleas for assistance, hardware for sale or to be given away "to a good home". LUGs near each other geographically sometimes get together to hold conferences and share knowledge among peers. For example, in Central America, in 2009, the first Encuentro Centro Americano de Software Libre was held in Nicaragua, where LUGs from the region, from Belize to Panama, attended. Groups from other countries are invited. In 2010, this conference was held in Nicaragua. In 2011, it was held in El Salvador; these events take place in summer, as most of the LUG members are students. As a second example, several Los Angeles-area LUGs sponsor and staff the annual Southern California Linux Expo conference. Many LUGs organize installfests, which are opportunities for experienced Linux users to help others novices with installation and configuration of Linux systems.
Installfests may have break-out sessions for teaching new tips and tricks—performance tuning, security hardening, etc. A few LUGs have developed projects of regional or international stature. For example, the Uganda Linux User Group operates in 3 major cities and coordinates national and international events that have featured guests as high-profile as Tim Berners-Lee. Cyberstorm.mu, a Linux User Group from Mauritius, trains high school students on Linux to compete in Google Code-in and organises Hackathons focused on Linux. The Bellingham Linux Users Group, in Bellingham, holds the annual Linuxfest Northwest, which attracts large numbers of participants from throughout the region, including western Canada. Bellevue Linux Users Group, which meets in a bookstore in Bellevue, has developed The Linux Information Project (LIN
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, it can be represented by the first seven digits; the last code digit, which may be 0-9 or an X, is a check digit. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, C=5. To calculate the check digit, the following algorithm may be used: Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at national libraries and coordinated by the ISSN International Centre based in Paris; the International Centre is an intergovernmental organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no information as to the publisher or its location. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats of the same online serial; this "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, the Web, it makes sense to consider only content, independent of media; this "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the indecs Content Model and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the
Criticism of Linux
The criticism of Linux focuses on issues concerning use of operating systems which use the Linux kernel. While the Linux-based Android operating system dominates the smartphone market in many countries, Linux is used on the New York Stock Exchange and most supercomputers, it is used in few desktop and laptop computers. Much of the criticism of Linux is related to the lack of desktop and laptop adoption, although as of 2015 there has been growing unease with the project's perspective on security and its adoption of systemd has been controversial; some security professionals say that the rise in prominence of operating system-level virtualization using Linux has raised the profile of attacks against the kernel, that Linus Torvalds is reticent to add mitigations against kernel-level attacks in official releases. Linux 4.12, released in 2017, enabled KASLR by default. Con Kolivas, a former kernel developer, tried to optimize the kernel scheduler for interactive desktop use, he dropped the support for his patches due to the lack of appreciation for his development.
In the 2007 interview Why I quit: kernel developer Con Kolivas he stated:If there is any one big problem with kernel development and Linux it is the complete disconnection of the development process from normal users. You know, the ones; the Linux kernel mailing list is the way to communicate with the kernel developers. To put it mildly, the Linux kernel mailing list is about as scary a communication forum as they come. Most people are terrified of mailing the list lest they get flamed for their inexperience, an inappropriate bug report, being stupid or whatever.... I think the kernel developers at large haven't got the faintest idea just how big the problems in userspace are. At LinuxCon 2009, Linux creator Linus Torvalds said that the Linux kernel has become "bloated and huge": Citing an internal Intel study that tracked kernel releases, Bottomley said Linux performance had dropped about two percentage points at every release, for a cumulative drop of about 12 percent over the last ten releases.
"Is this a problem?" he asked. - We're getting huge. Yes, it's a problem... Uh, I'd love to say we have a plan... I mean, sometimes it's a bit sad that we are not the streamlined, hyper-efficient kernel that I envisioned 15 years ago... The kernel is huge and bloated, our icache footprint is scary. I mean, there is no question about that, and whenever we add a new feature, it only gets worse. At LinuxCon 2014, Linux creator Linus Torvalds said he thinks the bloat situation is better because modern PCs are a lot faster: Torvalds said he'd love for Linux to shrink in size "We've been bloating the kernel over the last 20 years, but hardware has grown faster". In an interview with German newspaper Zeit Online in November 2011, Linus Torvalds stated that Linux has become "too complex" and he was concerned that developers would not be able to find their way through the software anymore, he complained that subsystems have become complex and he told the publication that he is "afraid of the day" when there will be an error that "cannot be evaluated anymore."Andrew Morton, one of Linux kernel lead developers, explains that many bugs identified in Linux are never fixed: Q: Is it your opinion that the quality of the kernel is in decline?
Most developers seem to be pretty sanguine about the overall quality problem. Assuming there's a difference of opinion here, where do you think it comes from? How can we resolve it? A: I used to think was in decline, I think that I might think that it still is. I see so many regressions. Theo de Raadt, founder of OpenBSD, compares OpenBSD development process to Linux: "Linux has never been about quality. There are so many parts of the system that are just these cheap little hacks, it happens to run.” As for Linus Torvalds, who created Linux and oversees development, De Raadt says, “I don’t know what focus is at all anymore, but it isn’t quality.” Critics of Linux on the desktop have argued that a lack of top-selling video games on the platform holds adoption back. As of September 2015, the Steam gaming service has 1,500 games available on Linux, compared to 2,323 games for Mac and 6,500 Windows games; as a desktop operating system, Linux has been criticized on a number of fronts, including: A confusing number of choices of distributions, desktop environments.
Audio handling. Poor open source support for some hardware, in particular drivers for 3D graphics chips, where manufacturers were unwilling to provide full specifications; as a result, many video cards have both open and closed source drivers with different levels of support. Limited availability of used commercial applications; this is a result of the software developers not supporting Linux rather than any fault of Linux itself. Sometimes this can be solved by running the Windows versions of these programs through Wine, a virtual machine, or dual-booting. So, this creates a chicken or the egg situation where developers make programs for Windows due to its market share, consumers use Windows due to availability of the programs. Another common complaint levelled against Linux is the abundance of distributions available; as of August, 2014, DistroWatch lists 285 major distributions. While Linux advocates have defended the number as an example of freedom of choice, other critics cite the large number as cause for confusion and lack of standardization in Linux operating systems.
Alexander Wolfe wrote in InformationWeek: Remember the 1980s worries about how the "forking" of Unix could hurt that operating
A Linux distribution is an operating system made from a software collection, based upon the Linux kernel and a package management system. Linux users obtain their operating system by downloading one of the Linux distributions, which are available for a wide variety of systems ranging from embedded devices and personal computers to powerful supercomputers. A typical Linux distribution comprises a Linux kernel, GNU tools and libraries, additional software, documentation, a window system, a window manager, a desktop environment. Most of the included software is free and open-source software made available both as compiled binaries and in source code form, allowing modifications to the original software. Linux distributions optionally include some proprietary software that may not be available in source code form, such as binary blobs required for some device drivers. A Linux distribution may be described as a particular assortment of application and utility software, packaged together with the Linux kernel in such a way that its capabilities meet the needs of many users.
The software is adapted to the distribution and packaged into software packages by the distribution's maintainers. The software packages are available online in so-called repositories, which are storage locations distributed around the world. Beside glue components, such as the distribution installers or the package management systems, there are only few packages that are written from the ground up by the maintainers of a Linux distribution. Six hundred Linux distributions exist, with close to five hundred out of those in active development; because of the huge availability of software, distributions have taken a wide variety of forms, including those suitable for use on desktops, laptops, mobile phones and tablets, as well as minimal environments for use in embedded systems. There are commercially backed distributions, such as Fedora, openSUSE and Ubuntu, community-driven distributions, such as Debian, Slackware and Arch Linux. Most distributions come ready to use and pre-compiled for a specific instruction set, while some distributions are distributed in source code form and compiled locally during installation.
Linus Torvalds developed the Linux kernel and distributed its first version, 0.01, in 1991. Linux was distributed as source code only, as a pair of downloadable floppy disk images – one bootable and containing the Linux kernel itself, the other with a set of GNU utilities and tools for setting up a file system. Since the installation procedure was complicated in the face of growing amounts of available software, distributions sprang up to simplify this. Early distributions included the following: H. J. Lu's "Boot-root", the aforementioned disk image pair with the kernel and the absolute minimal tools to get started, in late 1991 MCC Interim Linux, made available to the public for download in February 1992 Softlanding Linux System, released in 1992, was the most comprehensive distribution for a short time, including the X Window System Yggdrasil Linux/GNU/X, a commercial distribution first released in December 1992The two oldest and still active distribution projects started in 1993; the SLS distribution was not well maintained, so in July 1993 a new distribution, called Slackware and based on SLS, was released by Patrick Volkerding.
Dissatisfied with SLS, Ian Murdock set to create a free distribution by founding Debian, which had its first release in December 1993. Users were attracted to Linux distributions as alternatives to the DOS and Microsoft Windows operating systems on IBM PC compatible computers, Mac OS on the Apple Macintosh, proprietary versions of Unix. Most early adopters were familiar with Unix from school, they embraced Linux distributions for their low cost, availability of the source code for most or all of the software included. The distributions were a convenience, offering a free alternative to proprietary versions of Unix but they became the usual choice for Unix or Linux experts. To date, Linux has become more popular in server and embedded devices markets than in the desktop market. For example, Linux is used on over 50% of web servers, whereas its desktop market share is about 3.7%. Many Linux distributions provide an installation system akin to that provided with other modern operating systems. On the other hand, some distributions, including Gentoo Linux, provide only the binaries of a basic kernel, compilation tools, an installer.
Distributions are segmented into packages. Each package contains service. Examples of packages are a library for handling the PNG image format, a collection of fonts or a web browser; the package is provided as compiled code, with installation and removal of packages handled by a package management system rather than a simple file archiver. Each package intended for such a PMS contains meta-information such as a package description, "dependencies"; the package management system can evaluate this meta-information to allow package searches, to perform an automatic upgrade to a newer version, to check that all dependencies of a package are fulfilled, and/or to fulfill them automatically. Alth