Linux was developed as a freely distributable version of UNIX. UNIX is the most widely used
operating system in the world and has long been the standard for high-performance workstations and
larger servers. UNIX, first developed in 1969, has a strong programmer-oriented user group that
supports the operating system. Because UNIX is a commercial product, it must be bought for each
platform it runs on. Licensing fees for UNIX versions for PC machines range from a few hundred dollars
to several thousand. In an attempt to make UNIX widely available for no cost to those who want to
experiment with it, a number of public domain UNIX systems have been developed over the years. One
of the early UNIX work, alike was Minix, written by Andy Tanenbaum.
Although Minix didn't have a full range of features, it provided a small operating system that
could be used on PC machines. To expand on Minix, a number of users started developing an enhanced
operating system that would take advantage of the 80386 CPU's architecture. One of the primary
developers of this system, which .became known as Linux, was Linus Torvalds of the University of
Helsinki. He released an early version of Linux in 1991. A first commercial, almost bug-free release was
unleashed to the programming community in March 1992. Soon, many programmers were working on
Linux, and as the challenge and excitement of producing a growing UNIX work alike caught on, Linux
grew at a remarkable rate. As the number of developers working on Linux grew, the entire UNIX work
alike operating system was eventually completed and now includes all the tools you will find in a
commercial UNIX product.
Linux continues to grow as programmers adapt features and programs that were originally
written as commercial UNIX products to Linux. New versions of Linux and its utilities are appearing at an
astounding rate. New releases often appear weekly. To avoid any charges for -Linux, the Linux
developers do not use any code from other UNIX systems. There are no licensing fees involved with the
Linux operating system, and part of its mandate is to be freely available. Some companies have
undertaken the task of assembling and testing versions of Linux, which they package on a CD-ROM for a
(usually) minimal price. Linux is not based on a single version of UNIX; it is a consolidation of the best
features of BSD UNIX and System V.
BSD UNIX was developed at the University of California at Berkeley, starting in 1977. Several
major releases increased the power of BSD UNIX. Several standard UNIX programs originated at BSD,
although BSD stopped its UNIX development in the early 1990s. AT&T, which developed the first version
of UNIX, continued their UNIX development by producing a series of UNIX versions called System III,
System IV, and System V. Linux uses the last primary release of BSD UNIX called 4.4BSD as its base and
takes some other features from the latest release of System V, called System V Release 4 (SVR4).