doc_src/index.rst
.. highlight:: fish-docs-samples .. _intro:
Introduction
This is the documentation for :command:fish, the f\ riendly i\ nteractive sh\ ell.
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.
Some of the special features of fish are:
Extensive UI: :ref:Syntax highlighting <syntax-highlighting>, :ref:autosuggestions, :ref:tab completion <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 :ref:functions <syntax-function> can be added on the fly. The syntax is easy to learn and use.
This page explains how to install and set up fish and where to get more information.
If this is your first time using fish, see the :doc:tutorial <tutorial>.
If you are already familiar with other shells like bash and want to see the scripting differences, see :doc:Fish For Bash Users <fish_for_bash_users>.
For an overview of fish's scripting language, see :doc:The Fish Language <language>. If it would be useful in a script file, it's here.
For information on using fish interactively, see :doc:Interactive use <interactive>. If it's about key presses, syntax highlighting or anything else that needs an interactive terminal session, look here.
If you need to install fish first, read on, the rest of this document will tell you how to get, install and configure fish.
This section describes how to install, uninstall, start, and exit :command:fish. It also explains how to make fish the default shell.
Up-to-date instructions for installing the latest version of fish are on the fish homepage <https://fishshell.com/>_.
To install the development version of fish, see the instructions on the project's GitHub page <https://github.com/fish-shell/fish-shell>_.
Once fish has been installed, open a terminal. If fish is not the default shell:
Type :command:fish to start a shell::
fish
Type :command:exit to end the session::
exit
There are multiple ways to switch to fish (or any other shell) as your default.
The simplest method is to set your terminal emulator (e.g. GNOME Terminal, Apple's Terminal.app, or Konsole) to start fish directly. See its configuration and set the program to start to /usr/local/bin/fish (the exact path depends on how you installed fish).
Alternatively, you can set fish as your login shell so that it will be started by all terminal logins, including SSH.
.. warning::
Setting fish as your login shell may cause issues, such as an incorrect :envvar:`PATH`. Some operating systems, including a number of Linux distributions, require the login shell to be Bourne-compatible and to read configuration from ``/etc/profile``. fish may not be suitable as a login shell on these systems.
To change your login shell to fish:
Add the shell to /etc/shells with::
command -v fish | sudo tee -a /etc/shells
Change your default shell with::
chsh -s "$(command -v fish)"
To change it back to another shell, substitute fish with bash, tcsh or zsh as appropriate in the above command.
For uninstalling fish: see :ref:FAQ: Uninstalling fish <faq-uninstalling>.
Because shell scripts are written in many different languages, they need to carry information about which interpreter should be used to execute them. For this, they are expected to have a first line, the shebang line, which names the interpreter executable.
A script written in :command:bash would need a first line like this:
::
#!/bin/bash
When the shell tells the kernel to execute the file, it will use the interpreter /bin/bash.
For a script written in another language, just replace /bin/bash with the interpreter for that language. For example: /usr/bin/python for a python script, or /usr/local/bin/fish for a fish script, if that is where you have them installed.
If you want to share your script with others, you might want to use :command:env to allow for the interpreter to be installed in other locations. For example::
#!/usr/bin/env fish echo Hello from fish $version
This will call env, which then goes through :envvar:PATH to find a program called "fish". This makes it work, whether fish is installed in (for example) /usr/local/bin/fish, /usr/bin/fish, or ~/.local/bin/fish, as long as that directory is in :envvar:PATH.
The shebang line is only used when scripts are executed without specifying the interpreter. For functions inside fish or when executing a script with fish /path/to/script, a shebang is not required (but it doesn't hurt!).
When executing files without an interpreter, fish, like other shells, tries your system shell, typically /bin/sh. This is needed because some scripts are shipped without a shebang line.
To store configuration write it to a file called ~/.config/fish/config.fish.
.fish scripts in ~/.config/fish/conf.d/ are also automatically executed before config.fish.
These files are read on the startup of every shell, whether interactive and/or if they're login shells. Use status --is-interactive and status --is-login to do things only in interactive/login shells, respectively.
This is the short version; for a full explanation, like for sysadmins or integration for developers of other software, see :ref:Configuration files <configuration>.
If you want to see what you changed over fish's defaults, see :doc:fish_delta <cmds/fish_delta>.
To add ~/linux/bin to PATH variable when using a login shell, add this to ~/.config/fish/config.fish file::
if status --is-login
set -gx PATH $PATH ~/linux/bin
end
This is just an example; using :doc:fish_add_path <cmds/fish_add_path> e.g. fish_add_path ~/linux/bin which only adds the path if it isn't included yet is easier.
To run commands on exit, use an :ref:event handler <event> that is triggered by the exit of the shell::
function on_exit --on-event fish_exit
echo fish is now exiting
end
.. _more-help:
The GitHub page <https://github.com/fish-shell/fish-shell/>_
The official Matrix room <https://matrix.to/#/#fish-shell:matrix.org>_
The official mailing list at [email protected] <https://lists.sourceforge.net/lists/listinfo/fish-users>_
If you have an improvement for fish, you can submit it via the GitHub page.
.. toctree:: :maxdepth: 1
self faq interactive language commands fish_for_bash_users tutorial completions prompt design relnotes terminal-compatibility contributing license