Shell的起源与发展

1、The Thompson shell was the first Unix shell, introduced in the first version of Unix in 1971, and was written by Ken Thompson.

2、The Bourne shell was the default shell for Version 7 Unix. Developed by Stephen Bourne at Bell Labs, it was a replacement for the Thompson shell, whose executable file had the same name—sh. It was released in 1979 in the Version 7 Unix release distributed to colleges and universities.
3、Bash is a Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell. First released in 1989. The shell’s name is an acronym for Bourne Again Shell, a pun on the name of the Bourne shell that it replaces and the notion of being “born again”.
4、Zsh is an extended Bourne shell with many improvements, including some features of Bash, ksh, and tcsh. Paul Falstad wrote the first version of Zsh in 1990 while a student at Princeton University. The name zsh derives from the name of Yale professor Zhong Shao (then a teaching assistant at Princeton University) – Paul Falstad regarded Shao’s login-id, “zsh”, as a good name for a shell.