Linux

Article Index
Linux
Page #
Page #
All Pages

Page 1 of 3

Linux is a Unix-like computer operating system family. Linux is one of the most prominent examples of free software and of open source development; its underlying source code is available for anyone to use, modify, and redistribute freely.

After the Linux kernel was released to the public on 17 September 1991, the first Linux systems were completed by combining the kernel with system utilities and libraries from the GNU project, which led to the coining of the term GNU/Linux. From the late 1990s onward Linux gained the support of corporations such as IBM, Sun Microsystems, Hewlett-Packard, and Novell.

Predominantly known for its use in servers, Linux is used as an operating system for a wider variety of computer hardware than any other operating system, including desktop computers, supercomputers, mainframes, and embedded devices such as cellphones. Linux is packaged for different uses in Linux distributions, which contain the kernel along with a variety of other software packages tailored to requirements.

History

In 1991, Linus Torvalds began to work on the Linux kernel while he was attending the University of Helsinki. Torvalds originally intended Linux to be a non-commercial replacement for Minix, an educational operating system developed by Andrew S. Tanenbaum Linux was dependent on the Minix userspace at first.

The GNU Project, with the goal of creating a UNIX-like, POSIX-compatible operating system composed entirely of free software, had begun development in 1984, and a year later Richard Stallman had created the Free Software Foundation and wrote the first draft of the GNU General Public License (GPLv1). By the early 1990s, the project had produced or collected many necessary operating system components, including libraries, compilers, text editors, and a Unix shell, and the upper level could be supplied by the X Window System, but development of the lower level, which consisted of a kernel, device drivers and daemons had stalled and was incomplete.

The GPL allowed GNU code to be used in other projects, so long as they too were released under the GPL. In order to allow GNU code to be integrated with Linux, Torvalds changed his original license (which prohibited commercial redistribution) to the GPLv2. Linux and GNU developers worked to integrate GNU components with Linux. Thus Linux became a complete, fully functional free operating system.

In 2004, Ken Brown, president of the Alexis de Tocqueville Institution, published Samizdat, a highly controversial book which, among other criticism of open source, denied Torvalds' authorship of Linux (attributing it to Tanenbaum, instead). This was rebutted by Tanenbaum himself.

Development milestones

The Linux and GNU foundation formed the basis for an operating system which has since been completed by the efforts of numerous members of the free and open source software community. Significant milestones include:

The launch of the KDE desktop environment by Matthias Ettrich in October 1996 followed by the comparable GNOME alternative by Miguel de Icaza in August 1997, both based on the X11 windowing system developed at MIT. GNOME and KDE became Linux operating system shells, responsible for the direct contact with users.
The release of the Netscape browser's source code on March 31, 1998, which kicked off the Mozilla project that would eventually give birth to the popular Mozilla Firefox browser.

The release of StarOffice by Sun Microsystems which in June 2000 became the base for the free software OpenOffice.org office suite, a major event in the open source office world.
The growth of commercial interest in Linux is similarly marked by notable events: the launch in February 1998 of the Open Source Initiative; the announcement in July 1998 by Oracle Corporation that it would port its well-known database software to Linux and provide support for it; the IPOs of Red Hat on November 11, 1999 and VA Linux the following month which would create a speculative bubble; the wide-scale support of technology giant IBM that would spend millions of dollars on Linux, employing in 2005 close to 300 developers of the Linux kernel, and would organize starting in 2003 the legal defense for the SCO vs. Linux controversy against the attacks of the SCO Group that claimed copyright over the Linux kernel; and finally the acquisition in October and November 2003 of Ximian and then SuSE by the American technology company Novell.

Present day

Today Linux is used in numerous domains, from embedded systems to supercomputers,and has secured a place in server installations with the popular LAMP application stack. Torvalds continues to direct the development of the kernel. Stallman heads the Free Software Foundation, which in turn develops 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 combine and distribute the kernel, GNU components, and non-GNU components, with additional package management software in the form of Linux distributions.

Adoption

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. The actual installed user base may be higher than indicated by this figure, as most Linux distributions and applications are freely available and redistributable.

Desktop adoption is weaker than server adoption, with diverse calculations generally figuring between 0.3% and 3% as a function of the sample set and calculation methods used. According to market research company IDC, 25% of servers and 2.8% of desktop computers ran Linux as of 2004. The estimate of these numbers is driven by website traffic analysis, which may be complicated by two factors. First, many web browsers can modify their identity, either by default or via user action, by exploiting the user agent string, so as not to be blocked by websites that refuse to interact with browsers other than Internet Explorer running under Microsoft Windows. Second, a Linux system may be configured not to communicate this information for privacy and security reasons.

Linux Online alleges that people regard Linux as suitable mostly for computer experts because mainstream computer magazine reporters cannot explain what Linux is in a meaningful way, as they lack real life experience using it. Furthermore, 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. However, as of early 2007, significant progress in hardware compatibility has been made, and it is becoming increasingly common for hardware to work "out of the box" with many Linux distributions. Proponents and analysts attribute the relative success of Linux to its security, reliability, low cost, and freedom from vendor lock-in.

Naming

In 1992, Torvalds explained how he pronounces the word Linux:

“	'li' is pronounced with a short [ee] sound: compare prInt, mInImal etc. 'nux' is also short, non-diphtong, like in pUt. It's partly due to minix: linux was just my working name for the thing, and as I wrote it to replace minix on my system, the result is what it is... linus' minix became linux.	„
—Linus Torvalds, comp.os.linux newsgroup^[29]

Torvalds has made available an audio sample which indicates his own pronunciation, in English and Swedish English speakers may also pronounce the name as

The Free Software Foundation views Linux distributions which use GNU software as "variants" of the GNU system, and they ask that such operating systems be referred to as GNU/Linux or a Linux-based GNU system. However, the media and population at large refers to this family of operating systems as Linux. While some distributors make a point of using the aggregate form, most notably Debian with the Debian GNU/Linux distribution, its use outside of the enthusiast community is limited. The distinction between the Linux kernel and distributions based on it plus the GNU system is a source of confusion to many newcomers, and the naming remains controversial.

Copyright and Trademark

The Linux kernel and most GNU software are licensed under the GNU General Public License (GPL), version 2. The GPL requires that all distributed source code modifications and derived works also be licensed under the GPL, and is sometimes referred to as a "share and share-alike", "copyleft", or, pejoratively, a viral license. In 1997, Linus Torvalds stated, "Making Linux GPL'd was definitely the best thing I ever did." Other software 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. After more than ten years, the Free Software Foundation announced that they would be upgrading the GPL to version 3, citing increasing concerns with software patents and digital rights management (DRM). In particular, DRM is appearing in systems running copyleft software, a phenomenon dubbed "tivoization" after digital video recorder maker Tivo's use of DRM in their Linux-based appliances. Linus Torvalds has publicly stated on the Linux Kernel Mailing List that, based on the drafts of the license, he would not move the Linux kernel to GPL v.3, specifically citing the DRM provisions.

Source code analysis

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.^[40]

Most of the code (71%) was written in the C programming language, but many other languages were used, including C++, Lisp, assembly language, Perl, Fortran, Python 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.^[40]

In a later study, the same analysis was performed for Debian GNU/Linux version 2.2.This distribution contained over fifty-five million source lines of code, and the study estimated that it would have cost 1.9 billion dollars (year 2000 U.S. dollars) to develop by conventional means.

In March 2003, the SCO Group filed a lawsuit against IBM, claiming that IBM had contributed parts of SCO's copyrighted code to the Linux kernel, violating IBM's license to use Unix. Also, SCO sent letters to several companies warning that their use of Linux without a license from SCO may be actionable, and claimed in the press that they would be suing individual Linux users. Per the Utah District Court ruling on July 3, 2006; 182 out of 294 items of evidence provided by SCO against IBM in discovery were dismissed.

Trademark

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 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.