Introduction — fish-shell 3.4.1 documentation

# Introduction

This is the documentation for 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.

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.

This page explains how to install and set up fish and where to get more information.

## Where to go?

If this is your first time using fish, see the tutorial.

If you are already familiar with other shells like bash and want to see the scripting differences, see Fish For Bash Users.

For a comprehensive overview of fish’s scripting language, see The Fish Language.

For information on using fish interactively, see Interactive use.

If you need to install fish first, read on, the rest of this document will tell you how to get, install and configure fish.

## Installation

This section describes how to install, uninstall, start, and exit fish. It also explains how to make fish the default shell.

### Installation

Up-to-date instructions for installing the latest version of fish are on the fish homepage.

To install the development version of fish, see the instructions on the project’s GitHub page.

### Starting and Exiting

Once fish has been installed, open a terminal. If fish is not the default shell:

- Type fish to start a shell:

      > fish

- Type exit to end the session:

      > exit

### Default Shell

There are multiple ways to switch to fish (or any other shell) as your default.

The simpler is to set your terminal to start fish. See its configuration and set the program to start to `/usr/local/bin/fish` (if that’s where fish is installed - substitute another location as appropriate).

The more involved and complete way is to set fish as your login shell. To do that, you need to:

1. Add the shell to `/etc/shells` with:

       > echo /usr/local/bin/fish | sudo tee -a /etc/shells

2. Change your default shell with:

       > chsh -s /usr/local/bin/fish

Again, substitute the path to fish for /usr/local/bin/fish - see `command -s fish` inside fish. To change it back to another shell, just substitute `/usr/local/bin/fish` with `/bin/bash`, `/bin/tcsh` or `/bin/zsh` as appropriate in the steps above.

Warning

Setting fish as your login shell may have issues, because some operating systems (including a bunch of linux distributions) only do some of their configuration in shell startup files like /etc/profile. So you could notice e.g. $PATH being wrong, and you would have to redo that setup.

### Uninstalling

For uninstalling fish: see FAQ: Uninstalling fish.

### Shebang Line

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 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).

This line is only needed 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!).

## Configuration

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 Configuration files.

### Examples:

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 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 event handler that is triggered by the exit of the shell:

    function on_exit --on-event fish_exit
        echo fish is now exiting
    end

## Resources

- The GitHub page

- The official Gitter channel

- The official mailing list at fish-users@lists.sourceforge.net

If you have an improvement for fish, you can submit it via the GitHub page.

## Other help pages

- Introduction
- Frequently asked questions
- Interactive use
- The fish language
- Commands
- Fish for bash users
- Tutorial
- Writing your own completions
- Design
- Release notes
- License