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Distributions include the Linux kernel and supporting system software and libraries , many of which are provided by the GNU Project. Popular Linux distributions [18] [19] [20] include Debian , Fedora Linux , and Ubuntu , which in itself has many different distributions and modifications, including Lubuntu and Xubuntu.
Distributions intended for servers may omit graphics altogether, or include a solution stack such as LAMP. Because Linux is freely redistributable, anyone may create a distribution for any purpose. Linux was originally developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system. Linux also runs on embedded systems , i. Linux is one of the most prominent examples of free and open-source software collaboration.
The source code 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 Linux kernel, for example, is licensed under the GPLv2, with a special exception for system calls , as without the system call exception any program calling on the kernel would be considered a derivative and therefore the GPL would have to apply to that program. The availability of a high-level language implementation of Unix made its porting to different computer platforms easier.
As a result, Unix grew quickly and became widely adopted by academic institutions and businesses. Onyx Systems began selling early microcomputer-based Unix workstations in Later, Sun Microsystems , founded as a spin-off of a student project at Stanford University , also began selling Unix-based desktop workstations in While Sun workstations didn't utilize commodity PC hardware like Linux was later developed for, 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 by Richard Stallman , had the goal of creating a "complete Unix-compatible software system" composed entirely of free software. Work began in By the early s, 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.
Tanenbaum , a computer science professor, and released in 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 Linus Torvalds has stated on separate occasions that if the GNU kernel or BSD had been available at the time , he probably would not have created Linux.
While attending the University of Helsinki in the fall of , Torvalds enrolled in a Unix course. It was with this course that Torvalds first became exposed to Unix. In , he became curious about operating systems. Later, Linux matured and further Linux kernel development took place on Linux systems.
Linus Torvalds had wanted to call his invention " Freax ", a portmanteau of "free", "freak", and "x" as an allusion to Unix. During the start of his work on the system, some of the project's makefiles included the name "Freax" for about half a year. Initially, Torvalds considered the name "Linux" but dismissed it as too egotistical. To facilitate development, the files were uploaded to the FTP server ftp. 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.
Adoption of Linux in production environments, rather than being used only by hobbyists, started to take off first in the mids 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 , [31] [61] and have secured a place in server installations such as the popular LAMP application stack.
Use of Linux distributions in home and enterprise desktops has been growing. Linux's greatest success in the consumer market is perhaps the mobile device market, with Android being the dominant operating system on smartphones and very popular on tablets and, more recently, on wearables.
Linux gaming is also on the rise with Valve showing its support for Linux and rolling out SteamOS , its own gaming-oriented Linux distribution. Linux distributions have also gained popularity with various local and national governments, such as the federal government of Brazil.
Greg Kroah-Hartman is the lead maintainer for the Linux kernel and guides its development. These third-party components comprise a vast body of work and may include both kernel modules and user applications and libraries. Linux vendors and communities combine and distribute the kernel, GNU components, and non-GNU components, with additional package management software in the form of Linux distributions.
Many open source developers agree that the Linux kernel was not designed but rather evolved through natural selection. Torvalds considers that although the design of Unix served as a scaffolding, "Linux grew with a lot of mutations — and because the mutations were less than random, they were faster and more directed than alpha-particles in DNA.
Raymond considers Linux's revolutionary aspects to be social, not technical: before Linux, complex software was designed carefully by small groups, but "Linux evolved in a completely different way. From nearly the beginning, it was rather casually hacked on by huge numbers of volunteers coordinating only through the Internet.
Quality was maintained not by rigid standards or autocracy but by the naively simple strategy of releasing every week and getting feedback from hundreds of users within days, creating a sort of rapid Darwinian selection on the mutations introduced by developers.
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 the notable exception. The Project's implementation of the C 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 project also develops Bash , a popular CLI shell. Many other open-source software projects contribute to Linux systems. Installed components of a Linux system include the following: [78] [80]. The user interface , also known as 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. 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. 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 a user may interact with the application; however, certain extensions of the X Window System are not capable of working over the network.
Org Server , being the most popular. Server distributions might provide a command-line interface for developers and administrators, but provide a custom interface towards end-users, designed for the use-case of the system. This custom interface is accessed through a client that resides on another system, not necessarily Linux based.
Several types of window 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 , i3wm , or herbstluftwm provide 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. Wayland is a display server protocol intended as a replacement for the X11 protocol; as of [update] , it has not received wider 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.
Enlightenment has already been successfully ported since version Due to the complexity and diversity of different devices, and due to the large number of formats and standards handled by those APIs, this infrastructure needs to evolve to better fit other devices.
Also, a good userspace device library is the key of the success for having userspace applications to be able to work with all formats supported by those devices. The primary difference between Linux and many other popular contemporary operating systems is that the Linux kernel and other components are free and open-source software.
Linux is not the only such operating system, although it is by far the most widely used. Linux-based distributions are intended by developers for interoperability with other operating systems and established computing standards. Free software projects, although developed through collaboration , are often produced independently of each other.
The fact that the software licenses explicitly permit redistribution, however, provides a basis for larger-scale projects that collect the software produced by stand-alone projects and make it available all at once in the form of a Linux distribution. Many Linux distributions manage a remote collection of system software and application software packages available for download and installation through a network connection. This allows users to adapt the operating system to their specific needs.
Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. A distribution is responsible for the default configuration of the installed Linux kernel, general system security, and more generally integration of the different software packages into a coherent whole. Distributions typically use a package manager such as apt , yum , zypper , pacman or portage to install, remove, and update all of 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. 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. Online forums are another means for support, with notable examples being LinuxQuestions. 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 the development of the components of the system and of free software. 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 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. As computer hardware standardized throughout the s, 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.
First released in , the LLVM project provides an alternative cross-platform open-source compiler for many languages. A common feature of Unix-like systems, Linux includes traditional specific-purpose programming languages targeted at scripting , text processing and system configuration and management in general.
Linux distributions support shell scripts , awk , sed and make.
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