UNIX

The first version of UNIX was written in assembler language by American Telephone and Telegraph (ATT) in 1969. By 1973 it had been rewritten in the high level language C making it portable to other machines, a prime reason for its popularity today. By 1979 Berkeley University had developed an extended version. Since then many versions have developed but fortunately only three command language forms (known as ``shells''), and extensions based upon them, are common:-

• The Bourne shell (sh) -- the original shell.

• The Bourne Again shell (bash) -- an extended version of the Bourne shell used by Linux..

• The C shell (csh) -- Standard for Berkeley Software Distribution (BSD).

• The T C shell (tcsh) -- an extended version of the C shell.

• The Korn shell (ksh) -- Standard for System V from ATT.

UNIX is the first choice for Reduced Instruction Set Computers (RISC). There are a number of full screen interfaces based on X Windows. In the department we use a Linux - a version of UNIX developed by the GNU Free Software Foundation.