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GNU/Linux
Author : Jbuenol
From TechnologicalWiki
Contents |
[edit] History
GNU/Linux (or Linux to abbreviate) (commonly pronounced IPA: /ˈlɪnəks/ in English; variants exist) is the name usually given to any Unix-like computer operating system that uses the Linux kernel. Linux is one of the most prominent examples of free software and open source development: typically all underlying source code can be freely modified, used, and redistributed by anyone.
The name "Linux" comes from the Linux kernel, originally written in 1991 by Linus Torvalds. The system's utilities and libraries usually come from the GNU operating system, announced in 1983 by Richard Stallman. The GNU contribution is the basis for the alternative name GNU/Linux.
Predominantly known for its use in servers, Linux is supported by corporations such as Dell, Hewlett-Packard, IBM, Novell, Oracle Corporation, Red Hat, and Sun Microsystems. It is used as an operating system for a wide variety of computer hardware, including desktop computers, supercomputers, video game systems, such as the PlayStation 2 and PlayStation 3, several arcade games, and embedded devices such as mobile phones, routers, and stage lighting systems.
Very true! Makes a change to see soeomne spell it out like that. :)
Fell out of bed feeling down. This has brihgetned my day!
[edit] Design
Linux is a modular Unix-like operating system. It derives much of its basic design from principles established in Unix during the 1970s and 1980s. Linux uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are integrated directly with the kernel.
Much of Linux's higher-level functionality is provided by separate projects which interface with the kernel. The GNU userland is an important part of most Linux systems, providing the shell and Unix tools which carry out many basic operating system tasks. On top these tools a Linux system is formed with a graphical user interface that can be used, usually running in the X Window System.
[edit] User interface
Linux can be controlled by one or more of a text-based command line interface (CLI), graphical user interface (GUI) (usually the default for desktop), or through controls on the device itself (common on embedded machines).
On desktop machines, KDE, GNOME and Xfce are the most popular user interfaces, though a variety of other user interfaces exist. Most popular user interfaces run on top of the X Window System (X), which provides network transparency, feature that enables a graphical application running on one machine to be displayed and controlled from another.
Other GUIs include X window managers such as FVWM, Enlightenment and Window Maker. The window manager provides a means to control the placement and appearance of individual application windows, and interacts with the X window system.
A Linux system usually provides a CLI of some sort through a shell, which is the traditional way of interacting with a Unix system, but Linux distributions specialized for servers may use the CLI as its only interface. We can even find “headless systems” that run with no monitor at all, being controlled uniquely by the command line via a protocol such as SSH or Telnet.
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, providing very simple inter-process communication. A graphical terminal emulator program is often used to access the CLI from a Linux desktop.
[edit] Development
A summarised history of Unix-like operating systems is shown on the picture, starting from Linux's origins. Note that despite similar architectural designs and concepts being shared as part of the POSIX standard, Linux does not share any 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 the best-known and most widely used. Some free and open source software licences 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 GPL, is a form of copyleft, and is used for the Linux kernel and many of the components from the GNU project.
As an operating system underdog competing with mainstream operating systems, Linux cannot rely on a monopoly advantage; in order for Linux to be convenient for users, Linux aims for interoperability with other operating systems and established computing standards. Linux systems adhere to POSIX, SUS, ISO and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.
Free software projects, although developed in a collaborative fashion, are often produced independently of each other. However, given that the software licenses explicitly permit redistribution, this 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.
A Linux distribution, commonly called a “distro”, is a project that manages a remote collection of Linux-based software, and facilitates installation of a Linux operating system. Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. They include system software and application software in the form of packages, and distribution-specific software for initial system installation and configuration as well as later package upgrades and installs. A distribution is responsible for the default configuration of installed Linux systems, system security, and more generally integration of the different software packages into a coherent whole.
[edit] Community
A command line session using bashLinux 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.
In many cities and regions, local associations known as Linux Users Groups (LUGs) seek to promote Linux by extension free software. They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users. There are also many Internet communities that seek to provide support to Linux users and developers. Most distributions and open source projects have IRC chatrooms or newsgroups. Online forums are another means for support, with notable examples being LinuxQuestions.org and the Gentoo forums. 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 mainly focused on Linux. Linux Weekly News is a weekly digest of Linux-related news; the Linux Journal is an online magazine of Linux articles published monthly; Slashdot is a technology-related news website with many stories on Linux and open source software; Groklaw has written in depth about Linux-related legal proceedings and there are many articles relevant to the Linux kernel and its relationship with GNU on the GNU project's website. Print magazines on Linux often include cover disks including software or even complete Linux distributions.
Although Linux is generally available free of charge, several large corporations have established business models that involve selling, supporting, and contributing to Linux and free software. These include Dell, IBM, HP, Sun Microsystems, Novell, and Red Hat. The free software licenses on which Linux is based explicitly accommodate and encourage commercialization; the relationship between Linux 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.
I'm impressed! You've maaegnd the almost impossible.
HHIS I should have tuhoght of that!
[edit] Servers and supercomputers
Historically, Linux has mainly been used as a server operating system, and has risen to prominence in that area; Netcraft reported in September 2006 that eight of the ten most reliable internet hosting companies run Linux on their web servers. (As of June 2008, that figure has declined to five of the ten.) This is due to its relative stability and long uptime, and the fact that desktop software with a graphical user interface for servers is often unneeded. Enterprise and non-enterprise Linux distributions may be found running on servers. Linux is the cornerstone of the LAMP server-software combination (Linux, Apache, MySQL, Perl/PHP/Python) which has achieved popularity among developers, and which is one of the more common platforms for website hosting.
Linux is commonly used as an operating system for supercomputers. As of November 2007, out of the top 500 systems, 426 (85.2%) run Linux.
[edit] Embedded devices
Due to its low cost and ability to be easily modified, an embedded Linux is often used in embedded systems. Linux has become a major competitor to the proprietary Symbian OS found in the majority of smartphones — 16.7% of the smartphones sold worldwide during 2006 were using Linux — and it is an alternative to the proprietary Windows CE and Palm OS operating systems on mobile devices. Cell phones or PDAs running on Linux and built on an open source platform became a trend from 2007, like Nokia N810, Openmoko's Neo1973 and the on-going Google Android. The popular TiVo digital video recorder uses a customized version of Linux. Several network firewall and router standalone products, including several from Linksys, use Linux internally, using its advanced firewall and routing capabilities. The Korg OASYS and the Yamaha Motif XS music workstations also run Linux. Furthermore, Linux is used in the leading stage lighting control system, FlyingPig/HighEnd WholeHogIII Console.
[edit] Market share and uptake
Many quantitative studies of open source software focus on topics including market share and reliability, with numerous studies specifically examining Linux.The Linux market is growing rapidly, and the revenue of servers, desktops, and packaged software running Linux is expected to exceed $35.7 billion by 2008.
IDC's report for Q1 2007 says that Linux now holds 12.7% of the overall server market. This estimate was based on the number of Linux servers sold by various companies.
Estimates for the desktop market share of Linux range from less than one percent to almost two percent. In comparison, Microsoft operating systems hold more than 90%.
The frictional cost of switching operating systems and lack of support for certain hardware and application programs designed for Microsoft Windows have been two factors that have inhibited adoption. Proponents and analysts attribute the relative success of Linux to its security, reliability, low cost, and freedom from vendor lock-in.
Also most recently Google has begun to fund Wine, which acts as a compatibility layer, allowing users to run some Windows programs under Linux.
The XO laptop project of One Laptop Per Child is creating a new and potentially much larger Linux community, planned to reach several hundred million schoolchildren and their families and communities in developing countries. Six countries have ordered a million or more units each for delivery in 2007 to distribute to schoolchildren at no charge. Google, Red Hat, and eBay are major supporters of the project. While the XO will also have a Windows option, it will be primarilly deployed using RHEL.
[edit] Copyright and naming
The Linux kernel and most GNU software are licensed under the GNU General Public License (GPL). The GPL requires that anyone who distributes the Linux kernel must make the source code (and any modifications) available to the recipient under the same terms. In 1997, Linus Torvalds stated, “Making Linux GPL'd was definitely the best thing I ever did.” Other key components of a Linux 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 Window System uses the MIT License.
Torvalds has publicly stated that he would not move the Linux kernel (currently licensed under GPL version 2) to version 3 of the GPL, released in mid-2007, specifically citing some provisions in the new license which prohibit the use of the software in digital rights management.
A 2001 study of Red Hat Linux 7.1 found that this distribution contained 30 million source lines of code. 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 1.08 billion dollars (year 2000 U.S. dollars) to develop in the United States.
Most of the code (71%) was written in the C programming language, but many other languages were used, including C++, 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 a later study, the same analysis was performed for Debian GNU/Linux version 4.0. This distribution contained over 283 million source lines of code, and the study estimated that it would have cost 5.4 billion Euros to develop by conventional means.
In the United States, the name Linux is a trademark registered to Linus Torvalds. Initially, nobody registered it, but on August 15, 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. Torvalds has stated that he only trademarked the name to prevent someone else from using it, but was bound in 2005 by United States trademark law to take active measures to enforce the trademark. As a result, the LMI sent out a number of letters to distribution vendors requesting that a fee be paid for the use of the name, and a number of companies have complied.
