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= Linux =
======================================================================
Introduction
======================================================================
Linux ( ) is a family of free and open-source software Unix-like
operating systems based on the Linux kernel, which was first released
on 17 September 1991 by Linus Torvalds. Some members of the family are
typically packaged as a distribution (a.k.a. 'distro'), which includes
the kernel alongside supporting system software and libraries
developed by third parties--such as GNU, Red Hat, and X.Org--to create
a complete operating system; however, not all Linux-based operating
systems are considered distros, with Android being an example. Linux
was originally designed as a clone of Unix and is distributed under
the copyleft GPL license.
There are many thousands of Linux distributions, many based directly
or indirectly on other distributions; popular Linux distros include
Debian, Fedora Linux, Linux Mint, Arch Linux, and Ubuntu, while
commercial distributions include Red Hat Enterprise Linux, SUSE Linux
Enterprise, and ChromeOS. Linux distributions are frequently used in
server platforms. 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. There is controversy surrounding this. Other
than the Linux kernel, key components that make up a distribution may
include a display server (windowing system), a package manager, a
bootloader, and a Unix shell.
Linux is one of the most prominent examples of free and open-source
software collaboration. The Linux kernel is considered by many to be
the largest free and open source project. While originally developed
for x86-based personal computers, it has since been ported to more
platforms than any other operating system. When combined with Android,
which uses a Linux-based kernel and is designed for smartphones, they
have the largest installed base of all general-purpose operating
systems.
Overview
======================================================================
The Linux kernel was created 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 in development since 1983 by
the GNU Project, led by Richard Stallman. A working Unix system called
Minix was later released but its license was not entirely free at the
time and it was made for education purposes. The first entirely free
Unix for personal computers, 386BSD, did not appear until 1992, by
which time Torvalds had already built and publicly released the first
version of the Linux kernel on the Internet. Like GNU and 386BSD,
Linux did not have any Unix code, being a fresh re-implementation, and
therefore avoided legal issues from AT&T. Linux distributions
became popular in the 1990s and made Unix technologies accessible to
home users on personal computers whereas previously it had been
confined to sophisticated workstations.
Desktop Linux distributions include a windowing system such as X11 or
Wayland and a desktop environment such as KDE Plasma, GNOME, or Xfce.
Distributions intended for servers may not have a graphical user
interface at all or include 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, 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 .
Linux is, , used by around 4 percent of desktop computers. The
Chromebook, which runs the Linux kernel-based ChromeOS, dominates the
US K-12 education market and represents nearly 20 percent of sub-$300
laptop 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 (, having gradually displaced all competitors).
Linux also runs on embedded systems, i.e., devices whose operating
system 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).
Precursors
============
The Unix operating system was conceived of 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 a high-level language
implementation of Unix made its porting to different computer
platforms easier.
As a 1956 antitrust case forbade AT&T from entering the computer
business, AT&T provided the operating system's source code to
anyone who asked. As a result, Unix use grew quickly and it became
widely adopted by academic institutions and businesses. In 1984,
AT&T divested itself of its regional operating companies, and was
released from its obligation not to enter the computer business; freed
of that obligation, Bell Labs began selling Unix as a proprietary
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 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 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 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.
Creation
==========
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 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 the Linux kernel.
On 3 July 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 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 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.
Although not released until 1992, due to legal complications, the
development of 386BSD, from which NetBSD, OpenBSD and FreeBSD
descended, predated that of Linux. Linus Torvalds has stated that if
the GNU kernel or 386BSD had been available in 1991, he probably would
not have created Linux.
Copyright, trademark, and naming
==================================
Tux is sometimes stylized with incorporation of the GNU logo]]The
Linux kernel is licensed under the GNU General Public License (GPL),
version 2. The GPL requires that anyone who distributes software based
on source code under this license must make the originating source
code (and any modifications) available to the recipient under the same
terms. Other key components of a typical Linux distribution are also
mainly licensed under the GPL, but they may use other licenses; many
libraries use the GNU Lesser General Public License (LGPL), a more
permissive variant of the GPL, and the X.Org implementation of the X
Window System uses the MIT License.
Torvalds states that the Linux kernel will not move from version 2 of
the GPL to version 3. He specifically dislikes some provisions in the
new license which prohibit the use of the software in digital rights
management. It would also be impractical to obtain permission from all
the copyright holders, who number in the thousands.
A 2001 study of Red Hat Linux 7.1 found that this distribution
contained 30 million lines of source code. Using the Constructive Cost
Model, the study estimated that this distribution required about eight
thousand person-years of development time. According to the study, if
all this software had been developed by conventional proprietary
means, it would have cost about to develop in in the United States.
Most of the source code (71%) was written in the C programming
language, but many other languages were used, including C++, Lisp,
assembly language, Perl, Python, Fortran, and various shell scripting
languages. Slightly over half of all lines of code were licensed under
the GPL. The Linux kernel itself was 2.4 million lines of code, or 8%
of the total.
In the United States, the name 'Linux' is a trademark registered to
Linus Torvalds. Initially, nobody registered it. However, on 15 August
1994, William R. Della Croce Jr. filed for the trademark 'Linux', and
then demanded royalties from Linux distributors. In 1996, Torvalds and
some affected organizations sued him to have the trademark assigned to
Torvalds, and, in 1997, the case was settled. The licensing of the
trademark has since been handled by the Linux Mark Institute (LMI).
Torvalds has stated that he trademarked the name only to prevent
someone else from using it. LMI originally charged a nominal
sublicensing fee for use of the Linux name as part of trademarks, but
later changed this in favor of offering a free, perpetual worldwide
sublicense.
The Free Software Foundation (FSF) prefers 'GNU/Linux' as the name
when referring to the operating system as a whole, because it
considers Linux distributions to be variants of the GNU operating
system initiated in 1983 by Richard Stallman, president of the FSF.
The foundation explicitly takes no issue over the name Android for the
Android OS, which is also an operating system based on the Linux
kernel, as GNU is not a part of it.
A minority of public figures and software projects other than Stallman
and the FSF, notably distributions consisting of only free software,
such as Debian (which had been sponsored by the FSF up to 1996), also
use 'GNU/Linux' when referring to the operating system as a whole.
Most media and common usage, however, refers to this family of
operating systems simply as 'Linux', as do many large Linux
distributions (for example, SUSE Linux and Red Hat Enterprise Linux).
, about 8% to 13% of the lines of code of the Linux distribution
Ubuntu (version "Natty") is made of GNU components (the range
depending on whether GNOME is considered part of GNU); meanwhile, 6%
is taken by the Linux kernel, increased to 9% when including its
direct dependencies.
==== Naming ====
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. Torvalds considered the name
"Linux" but dismissed it as too egotistical.
To facilitate development, the files were uploaded to the FTP server
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".
According to a newsgroup post by Torvalds, the word "Linux" should be
pronounced ( ) with a short 'i' as in 'print' and 'u' as in 'put'. To
further demonstrate how the word "Linux" should be pronounced, he
included an audio guide with the kernel source code. However, in this
recording, he pronounces Linux as ' () with a short but close front
unrounded vowel, instead of a near-close near-front unrounded vowel as
in his newsgroup post.
Commercial and popular uptake
===============================
The adoption of Linux in production environments, rather than being
used only by hobbyists, started to take off first in the mid-1990s in
the supercomputing community, where organizations such as NASA started
replacing 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 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 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, and vehicles. 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 the
federal government of Brazil.
Development
=============
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 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.
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.
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, 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, Single UNIX
Specification (SUS), Linux Standard Base (LSB), ISO, and ANSI
standards where possible, although to date only one Linux distribution
has been POSIX.1 certified, Linux-FT. The Open Group has tested and
certified at least two Linux distributions as qualifying for the Unix
trademark, EulerOS and Inspur K-UX.
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.
Market share and uptake
=========================
Many quantitative studies of free/open-source software focus on topics
including market share and reliability, with numerous studies
specifically examining Linux. The Linux market is growing, and the
Linux operating system market size is expected to see a growth of
19.2% by 2027, reaching $15.64 billion, compared to $3.89 billion in
2019. Analysts project a Compound Annual Growth Rate (CAGR) of 13.7%
between 2024 and 2032, culminating in a market size of US$34.90
billion by the latter year. Analysts and proponents attribute the
relative success of Linux to its security, reliability, low cost, and
freedom from vendor lock-in.
; Desktops and laptops
: According to web server statistics (that is, based on the numbers
recorded from visits to websites by client devices), in October 2024,
the estimated market share of Linux on desktop computers was around
4.3%. In comparison, Microsoft Windows had a market share of around
73.4%, while macOS covered around 15.5%.
; Web servers
: W3Cook publishes stats that use the top 1,000,000 Alexa domains,
which estimate that 96.55% of web servers run Linux, 1.73% run
Windows, and 1.72% run FreeBSD.
: W3Techs publishes stats that use the top 10,000,000 Alexa domains
and the top 1,000,000 Tranco domains, updated monthly and estimate
that Linux is used by 39% of the web servers, versus 21.9% using
Microsoft Windows. 40.1% used other types of Unix.
: IDC's Q1 2007 report indicated that Linux held 12.7% of the overall
server market at that time; this estimate was based on the number of
Linux servers sold by various companies, and did not include server
hardware purchased separately that had Linux installed on it later.
: As of 2024, estimates suggest Linux accounts for at least 80% of the
public cloud workload, partly thanks to its widespread use in
platforms like Amazon Web Services (AWS), Microsoft Azure, and Google
Cloud Platform.
: ZDNet reports that 96.3% of the top one million web servers are
running Linux.
: W3Techs states that Linux powers at least 39.2% of websites whose
operating system is known, with other estimates saying 55%.
; Mobile devices
: Android, which is based on the Linux kernel, has become the dominant
operating system for smartphones. In April 2023, 68.61% of mobile
devices accessing websites using StatCounter were from Android.
Android is also a popular operating system for tablets, being
responsible for more than 60% of tablet sales . According to web
server statistics, Android has a market share of about 71%, with iOS
holding 28%, and the remaining 1% attributed to various niche
platforms.
; Film production
: For years, Linux has been the platform of choice in the film
industry. The first major film produced on Linux servers was 1997's
'Titanic'. Since then major studios including DreamWorks Animation,
Pixar, Weta Digital, and Industrial Light & Magic have migrated to
Linux. According to the Linux Movies Group, more than 95% of the
servers and desktops at large animation and visual effects companies
use Linux.
; Use in government
: Linux distributions have also gained popularity with various local
and national governments. News of the Russian military creating its
own Linux distribution has also surfaced, and has come to fruition as
the G.H.ost Project. The Indian state of Kerala has gone to the extent
of mandating that all state high schools run Linux on their computers.
China uses Linux exclusively as the operating system for its Loongson
processor family to achieve technology independence. In Spain, some
regions have developed their own Linux distributions, which are widely
used in education and official institutions, like gnuLinEx in
Extremadura and Guadalinex in Andalusia. France and Germany have also
taken steps toward the adoption of Linux. In April 2026 France ordered
its ministries to begin to replace 2.5 million Windows desktops with
Linux.
North Korea's Red Star OS, developed , is based on a version of
Fedora Linux.
Design
======================================================================
Many developers of free and open-source software software 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." Eric S. Raymond considers
Linux's revolutionary aspects to be social, not technical: before
Linux, complex software was designed carefully by small groups, but
"Linux evolved in a completely different way. From nearly the
beginning, it was rather casually hacked on by huge numbers of
volunteers coordinating only through the Internet. Quality was
maintained not by rigid standards or autocracy but by the naively
simple strategy of releasing every week and getting feedback from
hundreds of users within days, creating a sort of rapid Darwinian
selection on the mutations introduced by developers." Bryan Cantrill,
an engineer of a competing OS, agrees that "Linux wasn't designed, it
evolved", but considers this to be a limitation, proposing that some
features, especially those related to security, 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
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 a 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, 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,
some of the Linux community has sought to move to using Wayland as the
display server protocol, replacing X11.
Many other open-source software projects contribute to Linux systems.
Installed components of a Linux system include the following:
* A bootloader, for example GNU GRUB, LILO, SYSLINUX or systemd-boot.
This is a program that loads the Linux kernel into the computer's main
memory, by being executed by the computer when it is turned on and
after the firmware initialization is performed.
* An init program, such as the traditional sysvinit and the newer
systemd, OpenRC and Upstart. This is the first process launched by the
Linux kernel, and is at the root of the process tree. It starts
processes such as system services and login prompts (whether graphical
or in terminal mode).
* Software libraries, which contain code that can be used by running
processes. On Linux systems using ELF-format executable files, the
dynamic linker that manages the use of dynamic libraries is known as
ld-linux.so. If the system is set up for the user to compile software
themselves, header files will also be included to describe the
programming interface of installed libraries. Besides the most
commonly used software library on Linux systems, the GNU C Library
(glibc), there are numerous other libraries, such as SDL and Mesa.
** The C standard library is the library necessary to run programs
written in C on a computer system, with the GNU C Library being the
standard. It provides an implementation of the POSIX API, as well as
extensions to that API. For embedded systems, alternatives such as
musl, EGLIBC (a glibc fork once used by Debian) and uClibc (which was
designed for uClinux) have been developed, although the last two are
no longer maintained. Android uses its own C library, Bionic. However,
musl can additionally be used as a replacement for glibc on desktop
and laptop systems, as seen on certain Linux distributions like Void
Linux.
* Basic Unix commands, with GNU coreutils being the standard
implementation. Alternatives exist for embedded systems, such as the
copyleft BusyBox, and the BSD-licensed Toybox.
* Widget toolkits are the libraries used to build graphical user
interfaces (GUIs) for software applications. Numerous widget toolkits
are available, including GTK and Clutter developed by the GNOME
Project, Qt developed by the Qt Project and led by The Qt Company, and
Enlightenment Foundation Libraries (EFL) developed primarily by the
Enlightenment team.
* A package management system, such as dpkg and RPM. Alternatively
packages can be compiled from binary or source tarballs.
* User interface programs such as command shells or windowing
environments.
User interface
================
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. The dominant shell used in Linux 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 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"
or "X11". 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.
Several X display servers exist, with the reference implementation,
X.Org Server, being the most popular.
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 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 a different
window manager if preferred.
Wayland is a display server protocol intended as a replacement for the
X11 protocol; , 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.
Video input infrastructure
============================
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.
The diversity of hardware standards and data formats requires
continuous architectural refinement to maintain compatibility across
different device classes. Development focuses on providing robust
userspace libraries to abstract device complexity, ensuring that
applications can interface with varying formats without specialized
hardware-specific drivers.
Community
===========
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 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 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 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 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 the 1980s, it became more difficult for
hardware manufacturers to profit from this tactic, as the OS would run
on any manufacturer's computer that shared the same architecture.
Programming on Linux
======================
Most programming 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 the GNU toolchain, which includes the GNU Compiler
Collection (GCC) and the GNU Build System. Among 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 the Intel C++ Compiler, Sun Studio, and
IBM XL C/C++ Compiler. BASIC is available in procedural form from
QB64, PureBasic, Yabasic, GLBasic, Basic4GL, XBasic, wxBasic,
SdlBasic, and Basic-256, and in object oriented through Gambas,
FreeBASIC, B4X, Basic for Qt, Phoenix Object Basic, NS Basic,
ProvideX, Chipmunk Basic, RapidQ and Xojo. Pascal is implemented
through GNU Pascal, Free Pascal, Virtual Pascal, and graphically via
Lazarus, PascalABC.NET, or Delphi using FireMonkey (formerly through
Borland Kylix).
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. Many programs
also have an embedded programming language to support configuring or
programming themselves. For example, regular expressions are supported
in programs like grep and locate, the traditional Unix message
transfer agent Sendmail contains its own Turing complete scripting
system, and the advanced text editor GNU Emacs is built around a
general purpose Lisp interpreter.
Most distributions also include support for PHP, Perl, Ruby, Python
and other dynamic languages. While not as common, Linux also supports
C# and other CLI languages (via Mono), Vala, and Scheme. Guile Scheme
acts as an extension language targeting the GNU system utilities,
seeking to make the conventionally small, static, compiled C programs
of Unix design rapidly and dynamically extensible via an elegant,
functional high-level scripting system; many GNU programs can be
compiled with optional Guile bindings to this end. Many Java virtual
machines and development kits run on Linux, including the original Sun
Microsystems JVM (HotSpot), IBM's J2SE RE, and many open-source
projects like Kaffe and Jikes RVM; Kotlin, Scala, Groovy and other JVM
languages are also available.
GNOME and KDE are popular desktop environments and provide a framework
for developing applications. These projects are based on the GTK and
Qt widget toolkits, respectively, which can also be used independently
of the larger framework. Both support a wide variety of languages.
There are a number of Integrated development environments available
including Anjuta, Code::Blocks, CodeLite, Eclipse, Geany, ActiveState
Komodo, KDevelop, Lazarus, MonoDevelop, NetBeans, and Qt Creator,
while the long-established editors Vim, nano and Emacs remain popular.
Graphics and graphics design
==============================
A topic of perennial discussion is the area of graphic design on
Linux. Typical common graphics and image tools are programs such as:
GNU Image Manipulation Program (GIMP), Inkscape, Krita, DaVinci
Resolve, and Scribus.
Hardware support
======================================================================
The Linux kernel is a widely ported operating system kernel, available
for devices ranging from mobile phones to supercomputers; it runs on a
highly diverse range of computer architectures, including ARM-based
Android smartphones and the IBM Z mainframes. Specialized
distributions and kernel forks exist for less mainstream
architectures; for example, the ELKS kernel fork can run on Intel 8086
or Intel 80286 16-bit microprocessors, while the μClinux kernel fork
may run on systems without a memory management unit. The kernel also
runs on architectures that were only ever intended to use a
proprietary manufacturer-created operating system, such as Macintosh
computers (with PowerPC, Intel, and Apple silicon processors), PDAs,
video game consoles, portable music players, and mobile phones.
Linux has a reputation for supporting old hardware very well by
maintaining standardized drivers for a long time. There are several
industry associations and hardware conferences devoted to maintaining
and improving support for diverse hardware under Linux, such as
FreedomHEC. Over time, support for different hardware has improved in
Linux, resulting in any off-the-shelf purchase having a "good chance"
of being compatible.
In 2014, a new initiative was launched to automatically collect a
database of all tested hardware configurations.
Security
======================================================================
One commonly expressed attribute about Linux (or open source software
in general) is that through regular vetting by many individuals the
software is progressively made more secure, a process referred to as
being called "Linus's law". Linux is often highlighted for its share
of the estimated global servers market share. Besides many volunteers,
the not-for-profit bodies such as the Open Source Security Foundation
and Linux Foundation actively pursue ways to promote security in the
Linux platform as well.
See also
======================================================================
* Comparison of Linux distributions
* Comparison of open-source and closed-source software
* Comparison of operating systems
* Comparison of X Window System desktop environments
* Backward compatibility
* Criticism of Linux
* Linux kernel version history
* Linux Documentation Project
* Linux From Scratch
* Linux Software Map
* LinuxQuestions.org
* Linux User Group (LUG)
* List of Linux books
* List of free and open-source software packages
* List of live CDs
* Live USB
* List of software bugs
* List of computer security certifications
* List of computing and IT abbreviations
* List of Linux distributions
* List of games released on Linux
* List of open-source mobile phones
* List of operating systems
* Loadable kernel module
* Usage share of operating systems
* Timeline of operating systems
External links
======================================================================
* (archived)
* [https://kernel.org Linux kernel website and archives]
* [https://archive.org/details/git-history-of-linux The History of
Linux in GIT Repository Format 1992-2010] (archived)
License
=========
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Original Article: http://en.wikipedia.org/wiki/Linux
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