Fish (Unix shell)

Fish, the friendly interactive shell, is a Unix shell and scripting language first released in 2005 by Axel Liljencrantz, designed around user-friendliness and interactive discoverability out of the box, including syntax highlighting, automatic and context-aware suggestions, and a fully scriptable configuration, deliberately breaking from POSIX shell syntax where doing so simplifies common scripting patterns. Fish's scripting language differs enough from Bourne-family shells such as Bash and Zsh that most existing shell scripts require rewriting to run under it, a tradeoff its designers accepted in favor of a cleaner, more consistent syntax.