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]] ]]

<table align="right"><tr><td>]</td></tr><tr><td align="center">''Tux, the Linux penguin.''</td></tr></table>


'''Linux''' is the most popular ] computer ] ] and has been competing with ]. '''Linux''' is the most popular ] computer ] ] and has been competing with ].
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A kernel is not a complete ]. A complete system build around the Linux kernel is commonly known as the ], although advocates of the ] prefer to call the system ]. A kernel is not a complete ]. A complete system build around the Linux kernel is commonly known as the ], although advocates of the ] prefer to call the system ].


All Linux releases with an even sub-version (the second component) are part of a stable series, namely: 1.0.x, 1.2.x, 2.0.x, 2.2.x, and the current 2.4.x. All Linux releases with an even sub-version (the second component) are part of a stable series, namely: 1.0.x, 1.2.x, 2.0.x, 2.2.x, and the current 2.4.x.


The Linux mascot is a penguin named ], created by Larry Ewing.
⚫ === Architecture ===

⚫ == Architecture ==


Today Linux is a ]. ] and kernel extensions typically run in ], with full access to the hardware, although some run in ]. Unlike standard ], ] are easily configured as ], and loaded or unloaded while running the system. Also unlike standard monolithic kernels, device drivers can be pre-empted under certain conditions. This latter feature was added to handle ] correctly, and to improve support for ]. Today Linux is a ]. ] and kernel extensions typically run in ], with full access to the hardware, although some run in ]. Unlike standard ], ] are easily configured as ], and loaded or unloaded while running the system. Also unlike standard monolithic kernels, device drivers can be pre-empted under certain conditions. This latter feature was added to handle ] correctly, and to improve support for ].
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The complete source code of all versions of the Linux kernel can be browsed at http://lxr.linux.no. The complete source code of all versions of the Linux kernel can be browsed at http://lxr.linux.no.


=== Portability === == Portability ==


While Linus Torvalds didn't originally set out to make Linux a ] operating system, it has evolved in that direction. Linux is now in fact one of the most widely ported operating system kernels, running on systems as diverse as the ] (a handheld computer) to the ] (a massive, hugely expensive ]). Linux is intended to run as the main operating system on IBM's new ] ] architecture when it is finished. While Linus Torvalds didn't originally set out to make Linux a ] operating system, it has evolved in that direction. Linux is now in fact one of the most widely ported operating system kernels, running on systems as diverse as the ] (a handheld computer) to the ] (a massive, hugely expensive ]). Linux is intended to run as the main operating system on IBM's new ] ] architecture when it is finished.
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*]'s ] *]'s ]


=== Licensing Terms === == Licensing Terms ==

Initially, Torvalds released Linux under a license which forbade any commercial exploitation. This was soon changed to the ] (version 2 exclusively). This license allows distribution and even sale of possibly modified versions of Linux but requires that all those copies be released under the same license and be accompanied by source code. Initially, Torvalds released Linux under a license which forbade any commercial exploitation. This was soon changed to the ] (version 2 exclusively). This license allows distribution and even sale of possibly modified versions of Linux but requires that all those copies be released under the same license and be accompanied by source code.


He has publicly referred to licensing Linux under the GPL as the "best thing I ever did". He has publicly referred to licensing Linux under the GPL as the "best thing I ever did".


== See also == == See also ==
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* *
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Revision as of 13:43, 23 April 2003


File:Small Tux.png
Tux, the Linux penguin.

Linux is the most popular free computer operating system kernel and has been competing with Windows operating system.

It is a Unix-like system, written in C, and implements the POSIX standard. The Linux kernel was first developed by Finnish hacker Linus Torvalds in an attempt to provide a free Unix-like operating system that ran on Intel 80386 processors. The project was launched in 1991 in a famous post to the Usenet newsgroup comp.os.minix; the post can be found here.

From the early days, it received help from Minix hackers, and today it has received contributions from thousands of programmers.

Technically speaking, Linux is a kernel. The term "kernel" properly refers to the system software which provide a hardware abstraction layer, disk and filesystem control, multi-tasking, load-balancing, networking and security enforcement. A kernel is not a complete operating system. A complete system build around the Linux kernel is commonly known as the Linux operating system, although advocates of the free software movement prefer to call the system GNU/Linux.

All Linux releases with an even sub-version (the second component) are part of a stable series, namely: 1.0.x, 1.2.x, 2.0.x, 2.2.x, and the current 2.4.x.

The Linux mascot is a penguin named Tux, created by Larry Ewing.

Architecture

Today Linux is a hybrid monolithic kernel. Device drivers and kernel extensions typically run in ring 0, with full access to the hardware, although some run in user space. Unlike standard monolithic kernels, device drivers are easily configured as modules, and loaded or unloaded while running the system. Also unlike standard monolithic kernels, device drivers can be pre-empted under certain conditions. This latter feature was added to handle hardware interrupts correctly, and to improve support for symmetric multiprocessing.

The fact that Linux is not a microkernel was the topic of a famous flame war between Linus Torvalds and Andy Tanenbaum, a summary of which can be found at http://www.dina.dk/~abraham/Linus_vs_Tanenbaum.html

The complete source code of all versions of the Linux kernel can be browsed at http://lxr.linux.no.

Portability

While Linus Torvalds didn't originally set out to make Linux a portable operating system, it has evolved in that direction. Linux is now in fact one of the most widely ported operating system kernels, running on systems as diverse as the iPaq (a handheld computer) to the IBM S/390 (a massive, hugely expensive mainframe). Linux is intended to run as the main operating system on IBM's new Blue Gene supercomputer architecture when it is finished.

However, it is important to note that Linus's efforts were also directed successfully at a different sort of portability. Portability, according to Linus, was the ability to easily compile applications from a variety of sources on his system; thus Linux originally became popular in part because it required the least effort to get everybody's favorite GPLed and other open source applications running.

Linux currently runs on the following machine architectures:

Licensing Terms

Initially, Torvalds released Linux under a license which forbade any commercial exploitation. This was soon changed to the GNU General Public License (version 2 exclusively). This license allows distribution and even sale of possibly modified versions of Linux but requires that all those copies be released under the same license and be accompanied by source code.

He has publicly referred to licensing Linux under the GPL as the "best thing I ever did".

See also

Resources