UNIX

Desktop OS market share as of May, 2009
Microsoft Windows - 87.75%
Mac OS X and Mac OS - 9.81%
Linux - 0.99%
Solaris - 0.01%
Other - 1.44%

The history of UNIX and its variants

UNIX is a computer operating system. It was developed during the late 1960s at Bell Labs. It was made by Ken Thompson, Dennis Ritchie, Douglas McIlroy, and others. The system is a multiuser and multiprocessing system. This means that it can do many things at the same time. Also, many people can use it at the same time. It also is network oriented; which means that it is meant to operate in a network of computers. Security is also very important in UNIX, because of the multiuser idea, but also the networked environment it is found in.

Many ideas that were in UNIX were new. Other operating systems copied them. Today, there are many operating systems that have some of the ideas of UNIX in them. For this reason, some people talk about a "UNIX philosophy" of doing things. One of these systems with many of the UNIX ideas in it, is called Linux. Linux does not use code from UNIX, it only shares some of the ideas. Therefore Linux is not a UNIX operating system. Instead it is called "UNIX-like".

There can be many different users in a UNIX-like operating system. Most of them have a personal area where they can put things. This is called a user account.

The main method of interacting with a UNIX system is the command line interface. Users run commands and programs by typing them at the command line. This is an extremely powerful and flexible way of working, because it allows things to be done automatically, and is still used by most UNIX users and administrators.

A graphical user interface usually used by UNIX systems is the X Window System. The X Window System is only a shell of a graphical interface. It is made of many protocols. The X Window System itself does not provide decorations for windows or controls to the user to move and resize windows. This is handled by a window manager or desktop manager.

Some of the popular desktop environments and window managers are:

• Gnome
• KDE
• Windowmaker
• Xfce

Like most other graphical user interfaces, they use windows, dialog boxes, support the use of a computer mouse and are designed to be easy to use.

There are many thousands of programs available for the X Window System. Programs like word processors and spreadsheets are available including free and open-source software.

Two kinds

Today, there are two kinds of operating systems that look like Unix. The first group contains all those that have common kernel code with the original, developed at Bell Labs, later AT&T. This includes the commercial Unix variants, like Solaris, AIX or Mac OS X. The free ones do usually have BSD in their name, like FreeBSD, OpenBSD and NetBSD. The other group is based on the Linux Kernel (computer science). It does not have common code with the original UNIX. To avoid this controversy, many people therefore speak about Unix and Unix-like systems.

As to the applications; most can be made to run on either Unix or Linux. KDE and GNOME were developed for Linux, and later ported to the commercial Unix variants.

Other websites

• Manual Pages for Linux and FreeBSD - pages saying exactly what each command does