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 <http://fishshell.com/docs/current/tutorial.html> by searching for the magic phrase "unlike other shells".
fish is written in a sane subset of C++98, with a few components from C++TR1. It builds successfully with g++ 4.2 or later, and with clang. It also will build as C++11.
fish requires 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.
The source code for fish includes a large collection of tests. If you are making any changes to fish, running these tests is highly recommended to make sure the behaviour remains consistent.
Running the tests is only supported from the Autotools build. On OS X, you will require an installation of autoconf; we suggest using [Homebrew](http://brew.sh/) to install these tools.
The Travis Continuous Integration services can be used to test your changes across multiple platforms. You will need to [fork the fish-shell repository on GitHub](https://help.github.com/articles/fork-a-repo/), or push a copy of the code to your GitHub account.
1. [Sign in to Travis CI](https://travis-ci.org/auth) with your GitHub account, accepting the GitHub access permissions confirmation.
2. Once you're signed in, and your repositories are synchronised, go to your [profile page](https://travis-ci.org/profile) and enable the fish-shell repository.
fish requires PCRE2 due to the regular expression support contained in the `string` builtin. A bundled version will be compiled in automatically at build time if required.
fish requires a number of utilities to operate, which should be present on any Unix, GNU/Linux or OS X system. These include (but are not limited to) hostname, grep, awk, sed, which, and getopt. fish also requires the bc program.
In order to generate completions from man pages compressed with either lzma or xz, you may need to install an extra Python package. Python versions prior to 2.6 are not supported. For Python versions 2.6 to 3.2 you need to install the module `backports.lzma`. How to install it depends on your system and how you installed Python. Most Linux distributions should include it as a package named `backports-lzma` (or similar). From version 3.3 onwards, Python already includes the required module.
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).
