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(3) History

History of Shells

sh: aka "Bourne" shell, written by Steve Bourne at AT&T Bell Labs for Unix V7 (1979). Small, simple, and (originally) very few internal commands, so it called external programs for even the simplest of tasks. It is always available on everything that looks vaguely like Unix.
csh: The "C" shell. (Bill Joy, at Berkeley). Many things in common with the Bourne shell, but many enhancements to improve interactive use. The internal commands used only in scripts are very different from "sh", and similar (by design) to the "C" language syntax.
tcsh: The "TC" shell. Freely available and based on "csh". It has many additional features to make interactive use more convenient.
ksh: The "Korn" shell, written by David Korn of AT&T Bell Labs (now AT&T Research). Written as a major upgrade to "sh" and backwards compatible with it, but has many internal commands for the most frequently used functions. It also incorporates many of the features from tcsh which enhance interactive use (command line history recall etc.).
POSIX 1003.2 Shell Standard.: Standards committees worked over the Bourne shell and added many features of the Korn shell (ksh88) and C shell to define a standard set of features which all compliant shells must have.
bash: The "Bourne again" shell. Written as part of the GNU/Linux Open Source effort, and the default shell for Linux and Mac OS-X. It is a functional clone of sh, with additional features to enhance interactive use, add POSIX compliance, and partial ksh compatability.
zsh: A freeware functional clone of sh, with parts of ksh, bash and full POSIX compliance, and many new interactive command-line editing features. It was installed as the default shell on early MacOSX systems.

history.src last modified Mar 26, 2010

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