Fish

fish is the Friendly Interactive Shell.

Installation

For setting fish as the default shell system wide, see Command Shell#Changing default shell.

A user specific installation with Home Manager looks like this

home-manager.users.myuser = {
  programs.fish.enable = true;
};

Change myuser with the username you want to configure.

You can enable the fish shell and manage fish configuration and plugins with home manager, but to enable vendor fish completions provided by Nixpkgs you will also want to enable the fish shell in /etc/nixos/configuration.nix:

  programs.fish.enable = true;

Configuration

An example configuration in Home Manager for adding plugins and changing options could look like this

home-manager.users.myuser = {
  programs.fish = {
    enable = true;
    interactiveShellInit = ''
      set fish_greeting # Disable greeting
    '';
    plugins = [
      # Enable a plugin (here grc for colorized command output) from nixpkgs
      { name = "grc"; src = pkgs.fishPlugins.grc.src; }
      # Manually packaging and enable a plugin
      {
      name = "z";
      src = pkgs.fetchFromGitHub {
        owner = "jethrokuan";
        repo = "z";
        rev = "e0e1b9dfdba362f8ab1ae8c1afc7ccf62b89f7eb";
        sha256 = "0dbnir6jbwjpjalz14snzd3cgdysgcs3raznsijd6savad3qhijc";
      };
    }
  ];

See fishPlugins package set for available plugins in nixpkgs.

Useful scripts

Show that you are in a nix-shell

Add this to the fish_prompt function (usually placed in ~/.config/fish/functions/fish_prompt.fish):

set -l nix_shell_info (
  if test -n "$IN_NIX_SHELL"
    echo -n "<nix-shell> "
  end
)

and $nix_shell_info to the echo in that function, e.g.:

echo -n -s "$nix_shell_info ~>"

Now your prompt looks like this

• outside: ~>
• inside: <nix-shell> ~>

btw. you can directly start nix-shell in fish with nix-shell --run fish, but (FIXME) the normal build functions are not available there.

Environments

Helper functions that put you in a nix-shell with the given packages installed.

You can either put these in programs.fish.functions with home-manager or in ~/.config/fish/functions/fish_prompt.fish without.

haskellEnv

function haskellEnv
  nix-shell -p "haskellPackages.ghcWithPackages (pkgs: with pkgs; [ $argv ])"
end

# Invocation: haskellEnv package1 packages2 .. packageN

pythonEnv

function pythonEnv --description 'start a nix-shell with the given python packages' --argument pythonVersion
  if set -q argv[2]
    set argv $argv[2..-1]
  end
 
  for el in $argv
    set ppkgs $ppkgs "python"$pythonVersion"Packages.$el"
  end
 
  nix-shell -p $ppkgs
end

# Invocation: pythonEnv 3 package1 package2 .. packageN
# or:         pythonEnv 2 ..

See also

• Command Shell