Z-shell
The Z shell (zsh) is a Linux (Unix) shell that can be used both as an interactive, login shell and as a powerful shell script command interpreter. Zsh can be thought of as an extended bourne shell with a large number of improvements, including some of the most useful features of bash, ksh, and tcsh.
The first version of zsh was written by Paul Falstad in 1990 when he was a student at Princeton University.
Some features of note include:
Programmable command completion that can help you type both options and arguments for your most used commands (with out-of-the-box support for several hundred commands).
Share command history among all your running shells.
Extended file globbing lets you specify files without needing to run an external program like “find”.
Improved variable/array handling.
Edit multi-line commands in a single buffer.
Spelling correction.
Has various compatibility modes (e.g. you can have zsh pretend to be a bourne shell when run as /bin/sh).
Themeable prompts, including the ability to put prompt information on the right side of the screen and have it auto-hide when typing a long command.
Fully customizable.
Attesting to the sheer size of this shell is the now famous first sentence of the shell’s manual page which says “Because zsh contains many features, the zsh manual has been split into a number of sections”, and then goes on to list thirteen items.