Linux (operating system)

Tux the penguin, the Linux mascot

Linux is an operating system for Intel-based PC's, notable for running on the same hardware platform as the Windows operating system family, for being a very low-cost alternative to Windows, and for having a user experience nearly identical to the previously very popular Unix operating system. Since its advent in the early 1990's, Linux has proved a disruptive force within the computer industry.

Linux is open source software, which means it is written and improved upon through a community effort, and thus it can be obtained and used for free by anyone. Furthermore, numerous companies are able to earn money by offering "supported distributions" of Linux which have certain guarantees in terms of reliability and expected bug fixes, so customers who pay for one of the "supported" versions of Linux (such as Red Hat, or others) can rest assured that someone will help them if a serious problem arises. These specially packaged versions of Linux are called Linux distributions.

The origins of Linux are remarkable. The first Linux kernel was written by an upstart college student from Norway in 1991 in defiance of a competing effort by a renowned professor of computer architecture. The ensuing amicable debate between Linux' creator, Linus Torvalds, and Dr. Andrew Tanenbaum of Vrije Universitaet, The Netherlands, has been retold repeatedly with amusement and amazement.

Although first developed for the the Intel i386 architecture, Linux has since been ported to numerous hardware platforms, including Intel i686, AMD64, SPARC, and Xbox systems. Although it has been very successful in a server environment, Linux has also attained status as a viable desktop platform.

Naming

The original name 'Linux' came from the author's name, Linus, along with the "x" in Unix, to show that it is Unix-like. Linus originally intended to call the project "Freax", for Free and Freak, with the "x" denoting that it is Unix-like, but after one of his colleagues named the system's FTP directory after him, the name stuck.

GNU/Linux naming controversy

In 1984, The Free Software Foundation, founded by Richard M Stallman, made an attempt to create a free Unix-like operating system, which they called the GNU system.

They began with the necessary tools for the system, such as a compiler, debugger, and a text editor. Their plan was to then create a kernel to place beneath the tools that they had created. Unfortunately, the foundation was very late in producing a stable release, and even to this day development of the HURD (the GNU kernel) continues without a stable first release.

It was during this time that Torvalds first introduced his kernel. Before Linux, hackers had no choice but to use non-free kernels, most notably Minix. While the GNU kernel began to look more and more like vaporware every day, the community received Linux with open arms and many began to contribute.

From gnu.org: "Variants of the GNU operating system, which use the kernel called Linux, are now widely used; though these systems are often referred to as “Linux”, they are more accurately called GNU/Linux systems."

The GNU Project members decided to call 'Linux' GNU/Linux, in order to attribute credit to those who worked hard at creating the tools that the Linux kernel runs. Torvalds, however, has made no effort to hide his thoughts towards this naming convention, saying that "calling Linux in general just 'GNU/Linux' I think is ridiculous."

Pronunciation

Linux is pronounced like 'Minix' - that is, "'li' is pronounced with a short [ee] sound: compare prInt, mInImal etc.'nux' is also short, non-diphtong, like in pUt."

File system

As a Unix-like system, Linux maintains a hierarchical set of directories and permissions. Each file contains three basic permissions: read, write, and execute. Each directory and file is owned by a user account of the system and a (optional) group of users, and permission may be given to allow other users and groups to access the files as well, but only if the owner chooses to do so. This system is, while somewhat complicated, is very efficient, and has stood the test of time as a great prevention of malware.

The Linux kernel contains many directories. The following is a list of some of the most common:

Directory	Contents
bin	Contains essential commands, such as bash, cp, and rm
dev	Every device connected to the computer is held here, such as hard disks, wireless adapters, system memory, and so on
etc	Contains global system configurations, such as the X.org settings
home	Root of the user folders; contains documents and personalized settings for each individual
lib	Libraries called upon by the system applications; a collection of functions that are not specific to any one program alone
root	The home folder for the superuser
sbin	Houses the binaries necessary to the system, such as disk mounting tools
usr	Contains the majority of the program binaries, as well as shell commands
var	Slightly miscellaneous, this directory normally holds system logs and the HTTP directory

Distributions

Linux is typically found as a package of software known as a Linux distribution, also commonly referred to as a "distro". A Linux distribution provides an easy method of installing a Linux system. Distributions come in many forms, from LiveCDs, which extract the system onto a mounted sector of memory, to full installation DVDs. Among the most notable are Ubuntu, RedHat, and SUSE.

Software

Aside from the GNU project's applications, Linux is capable of running many applications of all natures, from games and graphic editors to Integrated Development Environments and web servers. Among the most commonly used applications are The GIMP photo editing tool, which is commonly referred to as a free alternative to Photoshop, Firefox, a very powerful, tabbed web browser, and OpenOffice, which is a free, full-featured alternative to the Microsoft Office suite.

See also

• Linux (kernel)
• Linux (distributions)
• Linux (history)

External Links

Linus' first post presenting Linux