fish is a smart and user-friendly command line shell for OS X, Linux, and the rest of the family. fish includes features like syntax highlighting, autosuggest-as-you-type, and fancy tab completions that just work, with no configuration required.
fish generally works like other shells, like bash or zsh. A few important differences can be found at <https://fishshell.com/docs/current/tutorial.html> by searching for the magic phrase "unlike other shells".
* a C++11 compiler. It builds successfully with g++ 4.8 or later, or with clang 3.3 or later. fish can be built using autotools or Xcode. autoconf 2.60 or later, as well as automake 1.13 or later, are required to build from git versions, but these are not required to build from the officially released tarballs.
* the headers and libraries of a curses implementation such as ncurses.
* gettext, for translation support.
* Doxygen 1.8.7 or newer, for building the documentation.
* a curses implementation such as ncurses (which should provide the `tput` command).
* gettext, if you need the localizations.
* PCRE2, due to the regular expression support contained in the `string` builtin. A copy is included with the source code, and will be used automatically if it does not already exist on your system.
Optional functionality should degrade gracefully. (If fish ever threw a syntax error or a core dump due to missing dependencies for an optional feature, it would be a bug in fish and should be reported on our GitHub.) Optional features and dependencies include:
* dynamically generating usage tips for builtin functions, which requires man, apropos, nroff, and ul.
* manual page parsing for auto-completion for external commands, which also requires the above man tools, plus Python 2.6+ or Python 3.3+. Python 2 will also need the backports.lzma package; Python 3.3+ should include the required module by default.
* the web configuration tool, which requires Python 2.6+ or 3.3+.
* the fish_clipboard_* functions (bound to \cv and \cx), which require xsel or pbcopy/pbpaste.
fish can also show VCS information in the prompt, when the current working directory is in a VCS-tracked project, with support for Git, Mercurial, and Subversion. This is one of the weakest dependencies, though: if you don't use git, for example, you don't need git information in the prompt, and if you do use git, you already have it. Similarly, fish comes with a variety of auto-completion scripts to help with command-line usage of a variety of applications; these scripts call the application in question, but you should only need these applications if you use them.
chsh will prompt you for your password, and change your default shell. Substitute "/usr/local/bin/fish" with whatever path to fish is in your /etc/shells file.
Questions, comments, rants and raves can be posted to the official fish mailing list at <https://lists.sourceforge.net/lists/listinfo/fish-users> or join us on our [gitter.im channel](https://gitter.im/fish-shell/fish-shell) or IRC channel [#fish at irc.oftc.net](https://webchat.oftc.net/?channels=fish). Or use the [fish tag on Stackoverflow](https://stackoverflow.com/questions/tagged/fish) for questions related to fish script and the [fish tag on Superuser](https://superuser.com/questions/tagged/fish) for all other questions (e.g., customizing colors, changing key bindings).
