Linux
Tux
the penguin, mascot of Linux [1]
|
Company /
developer |
Many |
Programmed in |
Various (Notably
C and
Assembly) |
OS family |
Unix-like |
Working state |
Current |
Source model |
Free and open source software with
proprietary components (firmware) |
Initial release |
1991 |
Latest stable release |
3.10.10 (29 August 2013; 3 days
ago)
[±][2] |
Latest unstable release |
3.11-rc7 (26 August 2013; 6
days ago)
[±][3] |
Marketing target |
Personal computers, mobile devices, embedded devices,
servers, mainframes, supercomputers |
Available
language(s) |
Multilingual |
Available
programming languages(s) |
Many |
Supported platforms |
Alpha,
ARC,
ARM,
AVR32,
Blackfin,
C6x,
ETRAX CRIS,
FR-V,
H8/300,
Hexagon,
Itanium,
M32R,
m68k,
META,
Microblaze,
MIPS,
MN103,
OpenRISC,
PA-RISC,
PowerPC,
s390,
S+core,
SuperH,
SPARC,
TILE64,
Unicore32,
x86,
Xtensa |
Kernel type |
Monolithic (Linux
kernel) |
Userland |
Various |
Default
user interface |
Many |
License |
Many[4]
("Linux" trademark owned by
Linus Torvalds[5]
and administered by the
Linux Mark Institute) |
Linux (i//
LIN-əks[6][7]
or
//
LEE-nuuks)[8][9][10]
is a
Unix-like computer
operating system assembled under the model of
free and open source software development and distribution. The
defining component of Linux is the
Linux kernel,[11]
an
operating system kernel first released on 5 October 1991, by
Linus Torvalds.[12][13]
Since the C
compiler that builds Linux and the main supporting
user space system tools and libraries originated in the
GNU Project, initiated in 1983 by
Richard Stallman, the
Free Software Foundation prefers the name
GNU/Linux when these tools and libraries are used.[14][15][16]
Linux was originally developed as a free operating system for
Intel x86-based personal computers. It has since been
ported
to more computer hardware platforms than any other operating system. It
is a leading operating system on
servers and other
big iron systems such as
mainframe computers and
supercomputers:[17][18][19][20]
more than 90% of today's
500 fastest
supercomputers run some variant of Linux,[21]
including the 10 fastest.[22]
Linux also runs on
embedded systems (devices where the operating system is typically
built into the
firmware and highly tailored to the system) such as mobile phones,
tablet computers, network
routers, building automation controls, televisions[23][24]
and
video game consoles; the
Android system in wide use on mobile devices is built on the Linux
kernel.
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—commercially or
non-commercially—by anyone under licenses such as the
GNU General Public License. Typically Linux is packaged in a format
known as a
Linux distribution for desktop and server use. Some popular
mainstream Linux distributions include
Debian (and its derivatives such as
Ubuntu and
Linux Mint),
Fedora (and its derivatives such as the commercial
Red Hat Enterprise Linux and its open equivalent
CentOS),
Mandriva/Mageia,
openSUSE (and its commercial derivative
SUSE Linux Enterprise Server), and
Arch Linux. Linux distributions include the Linux kernel, supporting
utilities and
libraries and usually a large amount of application software to
fulfill the distribution's intended use.
A distribution
oriented toward desktop use will typically include the
X Window System and an accompanying
desktop environment such as
GNOME or
KDE Plasma. Some such distributions may include a less resource
intensive desktop such as
LXDE or
Xfce for
use on older or less powerful computers. A distribution intended to run
as a server may omit all graphical environments from the standard
install and instead include other software such as the
Apache HTTP Server and an
SSH server such as
OpenSSH.
Because Linux is freely redistributable, anyone may create a
distribution for any intended use. Applications commonly used with
desktop Linux systems include the
Mozilla Firefox web browser, the
LibreOffice office application suite, and the
GIMP image
editor.
History
Antecedents
Unix
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, and
Joe Ossanna. It was first released in 1971 and was initially
entirely written in
assembly language, a common practice at the time. Later, in a key
pioneering approach in 1973, Unix was re-written in the programming
language
C by
Dennis Ritchie (with exceptions to the kernel and I/O). The
availability of an operating system written in a high-level language
allowed easier
portability to different computer platforms. With a legal glitch
forcing AT&T to license the operating system's source code to anyone who
asked,[25]
Unix quickly grew and became widely adopted by academic institutions and
businesses. In 1984, AT&T divested itself of Bell Labs. Free of the
legal glitch requiring free licensing, Bell Labs began selling Unix as a
proprietary product.
GNU
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.[26]
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
Unix shell, and a
windowing system) were completed, although low-level elements such
as
device drivers,
daemons, and the
kernel were stalled and incomplete.[27]
Linus Torvalds has said that if the
GNU kernel had been available at the time (1991), he would not have
decided to write his own.[28]
BSD
Although not released until 1992 due to
legal complications, development of
386BSD,
from which
NetBSD,
OpenBSD
and
FreeBSD descended, predated that of Linux.
Linus Torvalds has said that if 386BSD had been available at the
time, he probably would not have created Linux.[29]
MINIX
MINIX
is an inexpensive minimal
Unix-like operating system, designed for education in computer
science, written by
Andrew S. Tanenbaum. Starting with
version 3
in 2005, MINIX became
free and was redesigned for "serious" use.
Genesis
In 1991 while attending the
University of Helsinki, Torvalds became curious about operating
systems[30]
and frustrated by the licensing of MINIX, which limited it to
educational use only. He began to work on his own operating system which
eventually became the
Linux kernel.
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 development took place on Linux systems.[31]
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 projects 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.[32]
Developers worked to integrate GNU components with Linux to make a fully
functional and free operating system.[27]
Commercial and popular uptake
Ubuntu, a popular Linux distribution
Main article:
Linux adoption
Today, Linux systems are used in every domain, from
embedded systems to
supercomputers,[20][33]
and have secured a place in
server installations often using the popular
LAMP application stack.[34]
Use of Linux distributions in home and enterprise desktops has been
growing.[35][36][37][38][39][40][41]
They have also gained popularity with various local and national
governments. The federal government of Brazil is well known for its
support for Linux.[42][43]
News of the Russian military creating its own Linux distribution has
also surfaced, and has come to fruition as the G.H.ost Project.[44]
The Indian state of
Kerala
has gone to the extent of mandating that all state high schools run
Linux on their computers.[45][46]
China uses Linux exclusively as the operating system for its
Loongson processor family to achieve technology independence.[47]
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.
Portugal is also using its own Linux distribution
Caixa Mágica, used in the Magalhães netbook[48]
and the e-escola government program.[49]
France and Germany have also taken steps toward the adoption of Linux.[50]
Linux distributions have also become popular in the
netbook
market, with many devices such as the
ASUS Eee PC and
Acer Aspire One shipping with customized Linux distributions
installed.[51]
Current
development
Torvalds continues to direct the development of the kernel.[52]
Stallman heads the Free Software Foundation,[53]
which in turn supports the GNU components.[54]
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.
Design
A Linux-based system is a modular
Unix-like operating system. It derives 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, and
peripheral and
file system access.
Device drivers are either integrated directly with the kernel or
added as modules loaded while the system is running.
Separate projects that interface with the kernel provide much of the
system's higher-level functionality. The GNU
userland is an important part of most Linux-based systems, providing
the most common implementation of the
C library, a popular
shell, and many of the common
Unix tools which carry out many basic operating system tasks. The
graphical user interface (or GUI) used by most Linux systems is
built on top of an implementation of the
X Window System.
Some components of an installed Linux system are:
- A
bootloader - for example
GRUB or
LILO. This is a program which is executed by the computer when
it is first turned on, and loads the Linux kernel into memory.
- An init
program. This is the first
process launched by the Linux kernel, and is at the root of the
process tree: in other terms, all processes are launched through
init. It starts processes such as system services and login prompts
(whether graphical or in terminal mode)
-
Software libraries which contain code which can be used by
running processes. On Linux systems using
ELF-format executable files, the
dynamic linker which manages use of dynamic libraries is
"ld-linux.so". The most commonly used software library on Linux
systems is the
GNU C Library. If the system is set up for the user to compile
software themselves,
header files will also be included to describe the
interface of installed libraries.
- User interface programs such as command shells or windowing
environments
User interface
Main article:
Desktop Linux
The
user interface, also known as the
shell, is either a
command-line interface (CLI), a
graphical user interface (GUI), or through controls attached to the
associated hardware, which is common for embedded systems. For desktop
systems, the default mode is usually a graphical user interface,
although the CLI is available through
terminal emulator windows or on a separate
virtual console. Most low-level Linux components, including the GNU
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
extensive
desktop environments
KDE Plasma Desktop,
GNOME,
Cinnamon,
Unity and
Xfce,[55]
though a variety of additional user interfaces exist. Most popular user
interfaces are based on the
X Window System, often simply called "X". It provides
network transparency and permits a graphical application running on
one system to be displayed on another where a user may interact with the
application.[56]
Other GUIs may be classified as simple
X window managers, such as
FVWM,
Enlightenment, and
Window Maker, which provide a
minimalist functionality with respect to the desktop environments. A
window manager provides a means to control the placement and appearance
of individual application windows, and interacts with the X Window
System. The desktop environments include window managers as part of
their standard installations (Mutter
for GNOME,[57]
KWin for
KDE,[58]
Xfwm for Xfce as of January 2012[59])
although users may choose to use a different window manager if
preferred.
Development
Simplified history of
Unix-like operating systems. Linux shares similar
architecture and concepts (as part of the
POSIX standard) but does not share non-free source code
with the original
Unix or
MINIX.
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.[60]
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,[61]
SUS,[62]
LSB,
ISO, and
ANSI standards where possible, although to date only one Linux
distribution has been POSIX.1 certified, Linux-FT.[63][64]
Free software projects, although developed in a
collaborative fashion, 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, or "distros", 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
dpkg,
Synaptic,
YAST,
yum, 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. 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 for support, with notable examples
being
LinuxQuestions.org and the various distribution specific support and
community forums, such as ones for
Ubuntu,
Fedora, and
Gentoo. 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 include
cover disks including software or even complete Linux distributions.[65][66]
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. An analysis of the Linux kernel showed 75 percent of
the code from December 2008 to January 2010 was developed by programmers
working for corporations, leaving about 18 percent to volunteers and 7%
unclassified.[67]
Some of the major corporations that contribute include
Dell,
IBM,
HP,
Oracle,
Sun Microsystems (now part of Oracle),
SUSE, and
Nokia. A
number of 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 in order 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
Mac OS
prior to 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 Linux distributions support dozens of
programming languages. 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. Amongst others, GCC provides compilers for
Ada,
C, C++,
Java, and
Fortran.
First released in 2003, the
Low Level Virtual Machine project provides an alternative
open-source compiler for many languages.
Proprietary compilers for Linux include the
Intel C++ Compiler,
Sun Studio, and IBM XL
C/C++
Compiler.
BASIC in the form of
Visual Basic is supported in such forms as
Gambas,
FreeBASIC, and
XBasic,
and in terms of terminal programming or
QuickBASIC or
Turbo BASIC programming in the form of
QB64.
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, or
locate, while advanced text editors, like
GNU Emacs have a complete
Lisp interpreter built-in.
Most distributions also include support for
PHP,
Perl,
Ruby,
Python and other
dynamic languages. While not as common, Linux also supports
C# (via
Mono),
Vala, and
Scheme. A number of
Java Virtual Machines and development kits run on Linux, including
the original Sun Microsystems JVM (HotSpot),
and IBM's J2SE RE, as well as many open-source projects like
Kaffe and
JikesRVM.
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.[68]
Uses
As well as those designed for general purpose use on desktops and
servers, distributions may be specialized for different purposes
including:
computer architecture support,
embedded systems, stability, security, localization to a specific
region or language, targeting of specific user groups, support for
real-time applications, or commitment to a given desktop
environment. Furthermore, some distributions deliberately include only
free software. Currently, over three hundred distributions are
actively developed, with about a dozen distributions being most popular
for general-purpose use.[69]
Linux is a widely
ported
operating system kernel. The Linux kernel runs on a highly diverse range
of
computer architectures: in the hand-held
ARM-based
iPAQ and the
mainframe IBM
System z9,
System z10; in devices ranging from mobile phones to
supercomputers.[70]
Specialized distributions exist for less mainstream architectures. 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 manufacturer-created operating system,
such as
Macintosh computers (with both
PowerPC
and Intel
processors),
PDAs,
video game consoles,
portable music players, and mobile phones. See
List of Linux supported architectures.
There are several industry associations and hardware
conferences devoted to maintaining and improving support for diverse
hardware under Linux, such as
FreedomHEC.
Desktop
Main article:
Desktop Linux
The popularity of Linux on standard desktop computers and laptops has
been increasing over the years.[71]
Currently most distributions include a graphical user environment, with
the two most popular environments being
GNOME
(which can utilize additional
shells such as the default
GNOME Shell and
Ubuntu
Unity), and the
KDE Plasma Desktop.[citation
needed]
The performance of Linux on the desktop has been a controversial
topic; for example in 2007
Con Kolivas accused the Linux community of favoring performance on
servers. He quit Linux kernel development because he was frustrated with
this lack of focus on the desktop, and then gave a "tell all" interview
on the topic.[72]
Since then a significant amount of development has been undertaken in an
effort to improve the desktop experience. Projects such as
Upstart
and
systemd aim for a faster boot time.
Many popular applications are available for a wide variety of
operating systems. For example
Mozilla Firefox,
OpenOffice.org/LibreOffice
and
Blender have downloadable versions for all major operating systems.
Furthermore, some applications were initially developed for Linux, such
as
Pidgin, and
GIMP, and were ported to other operating systems including
Windows and
Mac OS X due to their popularity. In addition, a growing number of
proprietary desktop applications are also supported on Linux;[73]
see
List of proprietary software for Linux. In the field of animation
and visual effects, most high end software, such as
Autodesk Maya, Softimage XSI and
Apple Shake, is available for Linux, Windows and/or Mac OS X. There
are also
several companies that have ported their own or other companies'
games to Linux, with Linux also being a supported platform on both the
popular
Steam and
Desura
digital distribution services.[74]
Many other types of applications available for Microsoft Windows and
Mac OS X are also available for Linux. Commonly, either a
free software application will exist which does the functions of an
application found on another operating system, or that application will
have a version that works on Linux, such as with
Skype and
some
video games.[citation
needed] Furthermore, the
Wine project provides a Windows compatibility layer to run
unmodified Windows applications on Linux.
CrossOver is a proprietary solution based on the open source
Wine project that supports running Windows versions of
Microsoft Office,
Intuit
applications such as
Quicken
and
QuickBooks,
Adobe Photoshop versions through CS2, and many popular games such as
World of Warcraft and
Team Fortress 2. In other cases, where there is no Linux port of
some software in areas such as
desktop publishing[75]
and
professional audio,[76][77][78]
there is equivalent software available on Linux.
The collaborative nature of free software development allows
distributed teams to perform
language localization of some Linux distributions for use in locales
where localizing proprietary systems would not be cost-effective. For
example the
Sinhalese language version of the
Knoppix
distribution was available significantly before
Microsoft Windows XP was translated to Sinhalese.[citation
needed] In this case the
Lanka Linux User Group played a major part in developing the
localized system by combining the knowledge of university professors,
linguists, and local developers.
Installing, updating and removing software in Linux is typically done
through the use of package managers such as the
Synaptic Package Manager,
PackageKit, and
Yum Extender. While most major Linux distributions have extensive
repositories, often containing tens of thousands of packages, not all
the software that can run on Linux is available from the official
repositories. Alternatively, users can install packages from unofficial
repositories, download pre-compiled packages directly from websites, or
compile the source code by themselves. All these methods come with
different degrees of difficulty; compiling the source code is in general
considered a challenging process for new Linux users, but it is hardly
needed in modern distributions and is not a method specific to Linux.
- Sample Graphical Desktop Environments
-
-
-
-
-
-
-
-
-
-
Servers, mainframes and supercomputers
Servers designed for Linux
Linux distributions have long been used as
server operating systems, and have risen to prominence in that area;
Netcraft reported in September 2006 that eight of the ten most
reliable internet hosting companies ran Linux distributions on their
web
servers.[79]
Since June 2008, Linux distributions represented five of the top ten,
FreeBSD
three of ten, and
Microsoft two of ten;[80]
since February 2010, Linux distributions represented six of the top ten,
FreeBSD two of ten, and Microsoft one of ten.[81]
Linux distributions are the cornerstone of the
LAMP server-software combination (Linux,
Apache,
MariaDB/MySQL,
Perl/PHP/Python)
which has achieved popularity among developers, and which is one of the
more common platforms for website hosting.[82]
Linux distributions have become increasingly popular on
mainframes in the last decade partly due to pricing and the
open-source model.[20][citation
needed] In December 2009, computer giant
IBM reported
that it would predominantly market and sell mainframe-based Enterprise
Linux Server.[83]
Linux distributions are also commonly used as
operating systems for
supercomputers: since November 2010, out of the
top 500
systems, 459 (91.8%) run a Linux distribution.[84]
Linux was also selected as the operating system for the world's most
powerful supercomputer,[85]
IBM's
Sequoia which became operational in 2011.[86][clarification
needed]
Embedded devices
Due to its low cost and ease of customization,
Linux is often used in
embedded systems.
In the mobile sub-sector of the
Telecommunications equipment sector there are three major platforms
based on a more or less modified version of the Linux kernel:
mer,
Tizen and
Android. Android has become the dominant mobile operating system for
smartphones, during the second quarter of 2013, 79.3% of smartphones
sold worldwide used Android.[87]
Cell phones and PDAs running Linux on open-source platforms became more
common from 2007; examples include the
Nokia N810,
Openmoko's
Neo1973, and the
Motorola ROKR E8. Continuing the trend,
Palm (later acquired by
HP) produced a new Linux-derived operating system,
webOS,
which is built into its new line of
Palm
Pre smartphones.
In the non-mobile telecommunications equipment sector, the majority
of
Customer-premises equipment-hardware runs some Linux-based operating
system.
OpenWrt is a community driven example upon which many of the OEM
firmwares are based.
The popular
TiVo digital video recorder also uses a customized Linux,[88]
as do several network
firewalls and
routers from such makers as
Cisco/Linksys.
The
Korg OASYS, the
Korg KRONOS, the
Yamaha Motif XS/Motif XF
music workstations,[89]
Yamaha S90XS/S70XS, Yamaha MOX6/MOX8 synthesizers, Yamaha Motif-Rack XS
tone generator module, and Roland RD-700GX
digital piano also run Linux. Linux is also used in
stage lighting control systems, such as the WholeHogIII console.[90]
Please note: Embedded and real time segments are very vast
categories with different subcategories like
Automotive (e.g.
IVI,
Engine control unit,
GENIVI Alliance),
Avionics,
Health,
Medical Equipment,
Consumer Electronics,
Intelligent Homes,
Telecommunications and a couple more. The aggregated information
above could be very different for each subcategory taken separately. The
embedded segment is the largest segment in term of numbers of units.
Market share
and uptake
Main article:
Linux adoption
Many quantitative studies of
free / open source software focus on topics including market share
and reliability, with numerous studies specifically examining Linux.[91]
The Linux market is growing rapidly, and the revenue of servers,
desktops, and packaged software running Linux was expected to exceed
$35.7 billion by 2008.[92]
IDC's Q1 2007 report indicated that Linux held 12.7% of the overall
server market at that time.[93]
This estimate was based on the number of Linux servers sold by various
companies, and did not include server hardware purchased separately
which had Linux installed on it later. In September 2008 Microsoft CEO
Steve Ballmer admitted that 60% of web-servers run Linux versus 40%
that run
Windows Server.[94]
Primarily based on
web server statistics, the estimated market share of Linux on
desktop is 1.17%.[95]
In comparison,
Microsoft operating systems hold more than 85%.[35][36][37][38][39][40][41][96][97]
Analysts and proponents attribute the relative success of Linux to
its security, reliability, low cost, and freedom from
vendor lock-in.[98][99]
The
Wine compatibility layer allows users to run many programs designed
for Windows under Linux.[100]
About half of Wine's code has been contributed by volunteers and half
sponsored by commercial interests including
CodeWeavers, which produces a commercial version of the software.
Since 2009, Google has also provided funding to the Wine project.[101][102]
The
XO
laptop project of One Laptop Per Child is creating a new and
potentially much larger Linux community which is planned to reach
millions of schoolchildren and their families in the developing world.[103]
Major supporters of the project include
Google,
Red Hat,
and eBay.[104]
Although the XO will have a Windows option, it will be primarily
deployed with
Fedora Linux while using
Sugar as the desktop environment.
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.[105][106]
Since then major studios including
Dreamworks Animation,
Pixar,
Weta Digital, and
Industrial Light & Magic have migrated to Linux.[107][108][109]
According to the Linux Movies Group, more than 95% of the servers and
desktops at large animation and visual effects companies use Linux.[110]
Copyright, trademark, and naming
Linux and most GNU software are
licensed under the
GNU General Public License (GPL). The GPL requires that anyone who
distributes Linux must make the source code (and any modifications)
available to the recipient under the same terms. Other key components of
a software system 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[111][112]
(although GPLv3 has no such prohibition[citation
needed]) and it would also be impractical to obtain
permission from all the copyright holders, who number in the thousands.[113]
A 2001 study of
Red Hat Linux 7.1 found that this distribution contained 30 million
source lines of code.[114]
Using the
Constructive Cost Model, the study estimated that this distribution
required about eight thousand man-years of development time. According
to the study, if all this software had been developed by conventional
proprietary means, it would have cost about $1.44 billion (2013 US
dollars) to develop in the United States.[114]
Most of the 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.[114]
In a later study, the same analysis was performed for
Debian
GNU/Linux version 4.0 (etch, which was released in 2007).[115]
This distribution contained close to 283 million source lines of code,
and the study estimated that it would have required about seventy three
thousand man-years and cost US$7.94 billion (in 2013 dollars) to develop
by conventional means.
In the United States, the name Linux is a trademark registered
to Linus Torvalds.[5]
Initially, nobody registered it, but 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.[116]
The licensing of the trademark has since been handled by the
Linux Mark Institute. 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,[117]
but later changed this in favor of offering a free, perpetual worldwide
sublicense.[118]
GNU/Linux
The
Free Software Foundation views Linux distributions that use GNU
software as
GNU variants and they ask that such operating systems be referred to
as GNU/Linux or a Linux-based GNU system.[119]
The media and common usage, however, refers to this family of operating
systems simply as Linux, as do many large Linux distributions
(e.g.
SUSE Linux and
Mandriva Linux). Some distributions, notably
Debian,
use GNU/Linux. The naming issue remains controversial.
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External links