Zsh is a UNIX command interpreter (shell) that resembles the Korn shell
(ksh). It is not completely compatible. It includes many enhancements,
notably in the command-line editor, options for customizing its
behavior, file name globbing, features to make C-shell (csh) users feel
at home, and extra features drawn from tcsh (another `custom' shell).
Zsh is well known for its command line completion.