Fish, the Friendly Interactive SHell.

A shell is a program that helps you operate your computer by starting
other programs. Fish offers a command-line interface focused on
usability and interactive use.

Unlike other shells, fish does not follow the POSIX standard, but
still uses roughly the same model.

Some of the special features of fish are:

* Extensive UI: Syntax highlighting, Autosuggestions, tab completion
  and selection lists that can be navigated and filtered.
* No configuration needed: fish is designed to be ready to use
  immediately, without requiring extensive configuration.
* Easy scripting: New functions can be added on the fly. The syntax
  is easy to learn and use.