- First implemented in 1969 by Ken Thompson. (Same year Linus Travalds born)
- The name UNIX is a pun on MULTICS (Multiplexed Information and Computing Service)
- Initially it was written in assmbly. But later on was re-written in
C
At one point UNIX had 2 main distribution, one is called BSD
built by Ken along with his students, another one was System V(system five)
built by AT&T.
In 1984 Richard Staleman set to work on creating a free UNIX implementation.
At that time existing UNIX like OS (BSD and System V) was not freely available.
In response to that, he started a new project to create a free UNIX like system. The project was named GNU (GNU's not UNIX)
. Some important GNU project outcomes are GCC
, emacs
editor and bash
. By the early 1990 GNU had produced a system that is virtually complete, except a working kernel.
In 1991 Linus Torvalds a Finnish student was inspired to write an operatiog system for his intel 80386. He was using Minux
a small UNIX like operation system for his academic purpose. But that OS was not able to run all the softwares.
By late 1980's there were a wide variety of available UNIX implementations. Everybody was implementing things in their way. So it was essential to set a standard.
POSIX stands for Portable Operation System Interface. It has a trailing X
because most UNIX varients end in X.
POSIX.1 became IEEE standard in 1988. It defines a set of APIs. POSIX.1 is based on UNIX system calls and C library function API.