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Linux

Summary: This article is about Linux-based operating systems, GNU/Linux, and related topics. See Linux kernel for the kernel itself. Linux is also a brand of washing powder. Linux (pronounced Lih'Nuks) is a computer operating system. It is probably the best known example of free software and of open-source development. "Linux" strictly refers to the Linux kernel, but the name is often used to describe the entire Unix-like operating ...

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Linux

     From Wikipedia, the free encyclopedia.

This article is about Linux-based operating systems, GNU/Linux, and related topics. See Linux kernel for the kernel itself. Linux is also a brand of washing powder.
Linux (pronounced Lih'Nuks) is a computer operating system. It is probably the best known example of free software and of open-source development.

"Linux" strictly refers to the Linux kernel, but the name is often used to describe the entire Unix-like operating system formed by combining the Linux kernel with the GNU libraries and tools. This system is also known as GNU/Linux.

The term "Linux" is also used for whole Linux distributions, which typically bundle large quantities of software along with the operating system, such as web servers, programming languages, databases, desktop environments like GNOME and KDE and office suites like OpenOffice.org. Such distributions have experienced rapid growth in popularity, overtaking many proprietary versions of Unix and even challenging the dominance of Microsoft Windows in some areas.

Linux supports a vast range of computer hardware and has been deployed in applications ranging from personal computers to supercomputers and embedded systems such as mobile phoness and the TiVo PVR.

Initially developed and used mostly by individual enthusiasts, Linux has since gained the support of large companies like IBM and Hewlett-Packard. Analysts attribute this success to its vendor-independence, its low hardware cost and high speed compared to proprietary Unix and its security and reliability compared to Windows. These traits also serve as evidence of the utility of the open development model.

Table of contents
1 History
2 Linux distributions
3 Applications of Linux-based operating systems
4 Usability and market share
5 The scale of the Linux development effort
6 "GNU/Linux"
7 Litigation
8 Further reading
9 References
10 See also
11 External links

History

The Linux kernel was initially written as a hobby by Finnish university student Linus Torvalds, who was attending the University of Helsinki, as a free and modifiable Minix-like kernel. (Minix is a Unix-like teaching project designed for simplicity rather than production use.) Version 0.01 of Linux was released to the Internet in September 1991, 0.02 on October 5, 1991 [1]. Subsequently, thousands of volunteer developers throughout the world have participated in the project. The essay The Cathedral and the Bazaar discusses the development model of the Linux kernel and similar software.

The history of Linux-based operating systems is closely tied to that of the GNU project, a prominent free-software project led by Richard Stallman. The GNU project was begun in 1983 to develop a complete Unix-like operating system — compilers, application programs, development utilities and so on — composed entirely of free software. By 1991, when the first version of the Linux kernel was written, the GNU project had produced nearly all of the components of this system — except the kernel. Torvalds and other early Linux-kernel developers adapted their kernel to work with the GNU components to create a fully functional operating system. Linux thus filled the last major gap in the GNU plan. (Note that the Linux kernel is not part of the GNU project, although it is now licensed under the GNU General Public License.) Tux the penguin is the logo and mascot of Linux. The Linux trademark (SN: 1916230) is owned by Linus Torvalds, registered for "Computer operating system software to facilitate computer use and operation." The assignment of the trademark to Torvalds occurred after an attorney, one William R. Della Croce, Jr, in 1996 began sending letters to various Linux distributors claiming to own the "Linux" trademark and demanding 10% royalties. The distributors rapidly pooled resources, appealed the original trademark assignment and had it reassigned to Linus Torvalds. The licensing of the trademark is now handled by the Linux Mark Institute.

Linux distributions

Main article: Linux distribution There are many Linux distributions (distros), assembled by individuals, corporations and other organizations, and each may include any number of additional system software and application programs, as well as a program to install the whole system on a new computer.

The core of each distribution includes the Linux kernel, various software packages from the GNU project and elsewhere, including a shell and utilities such as libraries, compilers and editors. Most systems also include non-GNU tools and utilities, although these can be omitted and still leave a Unix-like system; examples include tools and utilities from BSD and its descendants and the X Window System. X provides the most common foundation for a graphical user interface on Linux systems.

Most distributions include a tremendous quantity of additional software. See List of open-source software packages.

Applications of Linux-based operating systems

Linux users, having traditionally had to install and configure their own system, have tended to be more technologically oriented than Microsoft Windows and Mac OS users, often revelling in the tag of "hacker" or "geek." This stereotype has been undermined in recent years by the increasing user-friendliness and broader adoption of many Linux distributions. Linux has made considerable progress in the server and special-purpose markets (e.g. image rendering and Web services), and is beginning to make inroads into the high volume "desktop" market.

Linux is the cornerstone of the LAMP server-software combination (Linux, Apache, MySQL, Perl/PHP/Python) that has achieved widespread popularity among web developers.

Linux is also commonly used as an embedded operating system. The low cost of Linux makes it possible to use it in devices such as the Simputer, a low-cost computer aimed especially at low-income populations in developing nations.

With desktop environments such as KDE and GNOME, Linux offers a user interface more like that of the Apple Macintosh or Microsoft Windows than the traditional Unix command line interface. Correspondingly, a number of graphical software packages are becoming available for Linux that offer much of the functionality of common commercial programs available on the other desktop operating systems, although the latter are still much greater in breadth and quantity.

Usability and market share

Once viewed as an operating system only computer geeks could appreciate, Linux is today a much more user-friendly system, with many graphical interfaces and applications that bear a greater resemblance to popular consumer operating systems than to the command line of Linux's Unix roots. However, there have been criticisms, even from Linux supporters, that Linux and other free software projects do not go far enough in terms of ensuring usability. The question of how Linux's usability compares to Windows or Macintosh remains a hotly debated topic. Its market share for desktop usage remains small but growing. According to market research company IDC, the 2002 Linux market share was 25% for servers and 2.8% for personal/desktop computers.

For those only familiar with Windows or the Macintosh, using Linux may be difficult because many things do not work identically, and substantial differences remain in more sophisticated administrative and configuration tasks. It is also usually easier to find skilled local technical support for Windows or MacOS than for Linux. Additionally, users will often have to switch application software as well, and equivalents of some programs may not be available (or there may be less selection, e.g. with games). Combined with an inherent reluctance to change operating systems (many users employ versions of Windows that are several years old) and the fact that most computers come with Windows pre-installed, this leads to an inherent inertia slowing adoption of new desktop operating systems.

However, argued advantages of Linux, such as lower cost, fewer security vulnerabilities, and lack of vendor lock-in have spurred a growing number of high-profile cases of mass adoption of Linux by corporations and governments. In those circumstances, some of the above obstacles are circumvented because only a few applications may be required and administration may be handled by a small number of skilled IT staff.

There have been competing studies of Linux's usability and cost. Relevantive, a Berlin-based company specializing in consulting companies on the usability of software and Web services, concluded in 2003 that the usability of Linux for a set of specific desktop-related tasks was "nearly equal to Windows XP." On the other hand, Microsoft-sponsored studies by IDC have argued that Linux has a higher total cost of ownership (TCO) than Windows.

Linux has also been criticized for having unpredictable development schedules, thus making enterprise users less comfortable with Linux than they might be with another operating system (Marcinkowski, 2003). The large number of choices in Linux distributions has also been argued to confuse consumers and software vendors. On the other hand, Linux supporters have pointed out that Microsoft release dates also have a reputation for unreliability, and there are many known incompatibilities between different versions of Windows.

Installation

Difficulty of installation was initially a barrier to adoption, but the installation process has been greatly eased in recent years, some distributions being easier to install than comparable versions of Windows.

With the adoption of Linux by several large PC manufacturers, computers with Linux distributions pre-installed have become available.

Some distributions (such as Knoppix/Gnoppix and Gentoo) allow Linux to be booted directly from a live CD without modifying the hard drive. CD ISO images for these and other distributions can usually be downloaded from the Internet, burneded to a CD and booted from the CD.

Linux can also be booted over a network or, for a minimal system, from a few floppy disks or network card NetBoot flash drivers (see Isolinux).

Configuration

Configuration of most settings is stored in a directory called /etc, while others store settings in hidden files in the user's home directory. Some programs use a configuration database instead of files.

There are a number of ways to change these settings. The most common way to do this is using tools provided by distributions such as SuSE's YaST or Mandrake's Control Center. There are non-distribution-specific utilities such as Linuxconf and the GNOME System Tools. There are also many command line utilities for configuring programs. Finally, since most settings are stored in text files they can be configured by any text editor.

Support

Support is generally provided by peers — other Linux users, usually online, in forums, newsgroups and mailing lists. Linux User Groups (or LUGs) have sprung up all over the world as a way of assisting local users, new and experienced alike, with the installation, use, maintenance and advocacy of Linux systems.

Commercial suppliers of Linux distributions generally have a business model of providing support. Third-party support is also readily available.

The scale of the Linux development effort

One study (More Than a Gigabuck: Estimating GNU/Linux's Size [1]) of Red Hat Linux 7.1 found that this particular distribution contained 30 million physical source lines of code (SLOC). Using the COCOMO cost model, the study estimated that this distribution required about 8,000 person-years of development time. Had all this software been developed by conventional proprietary means, it would have cost over $1.08 billion ($1,080 million), in year 2000 dollars, to develop in the US.

The majority of the code (71%) was in C, but many other languages were used, including C++, shell scripts, Lisp, assembly language, Perl, Fortran and Python.

Slightly over half of all its code (counting by line) was licensed under the GPL.

The Linux kernel contained 2.4 million lines of code, or 8% of the total, showing that the vast majority of a Linux distribution consists of code that is not contained in the Linux kernel.

"GNU/Linux"

Main article: GNU/Linux naming controversy Because the GNU facilities — without which the system would not resemble Unix from a user perspective — stem from a long-standing and well-integrated free operating system project that predates the Linux kernel itself and which the kernel was changed early on specifically to fit into, Richard Stallman of GNU/FSF asks that the combined system (regardless of distribution) be referred to as "GNU/Linux." Some people do — notably the Debian project — although most simply call the system "Linux." The distinction between Torvalds' kernel and entire Linux-based operating system distributions (of which the kernel forms only a small part) is a perennial source of confusion, and the naming remains controversial.

Litigation

Main article: SCO v. IBM In March 2003, the SCO Group (SCOG) filed a lawsuit against IBM claiming that IBM had included portions of SCOG's intellectual property into the Linux kernel in violation of IBM's license to use UNIX, now claimed to be held by SCOG. Additionally, SCOG sent letters to a number of companies warning them that their use of Linux without a license from SCOG may be actionable, and have claimed in the press that they would be suing individual Linux users. This controversy has also evoked lawsuits by SCOG against Novell, DaimlerChrysler and AutoZone as well as by Red Hat and others against SCOG.

Further reading

  • Glyn Moody: Rebel Code: Linux and the Open Source Revolution, Perseus Publishing, ISBN 0-713-99520-3

References

  • Gedda. R. (2004). Linux breaks desktop barrier in 2004: Torvalds. Retrieved January 16, 2004 from [1]
  • Mackenzie, K. (2004). Linux Torvalds Q&A. Retrieved January 19, 2004 from [1]
  • Marcinkowski, A. (2003). Linux needs reconsideration. Retrieved January 16, 2004 from [1]

See also

External links

General information

Newbie and user-friendliness in Linux

Linux distributions

Reference

Tutorials

Free Online Training

Professional Linux Training

Online publications

Printed publications

Linux and GNU

Linux kernel

Linux hardware

Linux News

Popular Linux Flavors/Versions/Distributions

There exist a very large number of Linux distributions. These are only some of the most popular:

Linux on Windows

Installing and running Linux on an existing Windows installation without a separate partition.

  • colinux (for running Linux natively on Windows)
  • Lnx4Win
  • WinLinux
  • Bochs (PC emulator — for installing Linux on Windows or any OS on another OS)
  • Qemu (A Just-in-time emulator for running applications or OSes from one machine on another)
  • Knoppix (a distribution that boots from a live CD)

Scholarship and grant support

Other

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This article is from Wikipedia. This article was up-to-date as of 8 May 2004 - See live article
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