Introduction to Linux

Linux is a completely free reimplementation of the POSIX specification, with SYSV and BSD extensions

(which means it looks like Unix, but does not come from the same source code base), which is available in

both source code and binary form. Its copyright is owned by Linus Torvalds and

other contributors, and is freely redistributable under the terms of the GNU General Public License (GPL). A

copy of the GPL is included with the Linux source; you can also get a copy from

ftp://prep.ai.mit.edu/pub/gnu/COPYING

Linux, per se, is only the kernel of the operating system, the part that controls hardware, manages files,

separates processes, and so forth. There are several combinations of Linux with sets of utilities and

applications to form a complete operating system. Each of these combinations is called a distribution of

Linux. The word Linux, though it in its strictest form refers specifically to the kernel, is also widely and

correctly to refer to an entire operating system built around the Linux kernel. For a list and brief discription of

various distributions, see http://sunsite.unc.edu/LDP/HOWTO/Distribution−HOWTO.htmlNone of these

distributions is ``the official Linux''.

Linux is not public domain, nor is it `shareware'. It is `free' software, commonly called freeware or Open

Source Software[tm] (see http://www.opensource.org), and you may give away or sell copies, but you must

include the source code or make it available in the same way as any binaries you give or sell. If you distribute

any modifications, you are legally bound to distribute the source for those modifications. See the GNU

General Public License for details.

Linux is still free as of version 2.0, and will continue to be free. Because of the nature of the GPL to which

Linux is subject, it would be illegal for it to be made not free. Note carefully: the `free' part involves access to

the source code rather than money; it is perfectly legal to charge money for distributing Linux, so long as you

also distribute the source code. This is a generalization; if you want the fine points, read the GPL.

Linux runs on 386/486/Pentium machines with ISA, EISA, PCI and VLB busses. MCA (IBM's proprietary

bus) is not well−supported in 2.0.x and earlier versions, but support has been added to the current them.

In contrast, the closed and centralized model means that there is only one person or team working on the

project, and they only release software that they think is working well. Often this leads to long intervals

between releases, long waiting for bug fixes, and slower development. The latest release of such software to

the public is sometimes of higher quality, but the development speed is generally much slower.