Zsh is a shell ( command interpreter ) of the Bourne shell family, which also includes bash and the Korn shell (which zsh is said to resemble). Developed by Paul Falstad, zsh was intended to be a replacement for both the Bourne and C shell . It incorporates features of all the other shells (such as file name completion and a history mechanism) as well as new capabilities. Zsh is considered similar to the Korn shell. Falstad intended to create in zsh a shell that would do whatever a programmer might reasonably hope it would do. Zsh is popular with advanced users.