What is zsh?
Zsh is a UNIX command interpreter (shell) usable as an
interactive login shell and as a shell script command pro-
cessor. Of the standard shells, zsh most closely resembles
ksh but includes many enhancements. Zsh has comand line
editing, builtin spelling correction, programmable command
completion, shell functions (with autoloading), a history
mechanism, and a host of other features.