C Shell

The C shell (csh) is a Unix shell developed by Bill Joy for the BSD Unix system. It was originally derived from the 6th Edition Unix /bin/sh (which was the Thompson shell), the predecessor of the Bourne shell. Its syntax is modeled after the C programming language. The C shell added many feature improvements over the Bourne shell, such as aliases and command history. Today, the original C shell is not in wide use on Unix; it has been superseded by other shells such as the Tenex C shell (tcsh) based on the original C shell code, but adding filename completion and command line editing, comparable with the Korn shell (ksh), and the GNU Bourne-Again shell (bash). An independently-developed and modernized C shell, created by Nicole Hamilton, also survives on Windows in the form of Hamilton C shell.
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<operating system> (csh) The Unix command-line interpreter shell and script language by William Joy, originating from Berkeley Unix.
Unix systems up to around Unix Version 7 only had one shell - the Bourne shell, sh. Csh had better interactive features, notably command input history, allowing earlier commands to be recalled and edited (though it was still not as good as the VMS equivalent of the time).
Presumably, csh's C-like syntax was intended to endear it to programmers but sadly it lacks some sh features which are useful for writing shell scripts so you need to know two different syntaxes for every shell construct.
A plethora of different shells followed csh, e.g. tcsh, ksh, bash, rc, but sh and csh are the only ones which are provided with most versions of Unix.
(1998-04-04)