sh, csh, ksh, ...


There are various shells, and they only differ in details
Syntax for uncommon operation
Featureful/featureless in user interaction
Executable size

The most important families are
sh: the pristine one, the Bourne shell (by Steve Bourne)
csh: the "C" shell, from Berkeley tradition
ksh: Korn shell, by mr. Korn

In GNU/Linux systems we usually have these options
bash (Bourne Again Shell)
ash (sh-compatible, but much smaller than bash)
dash (Debian Almquist Shell -- a modern ash)
zsh (sh-compatible, not huge as bash nor minimal as dash)
tcsh (csh compatible, quite out of fashion by now)