{ pkgs, lib, ... }:
{
  # https://nixos.wiki/wiki/Fish#Setting_fish_as_your_shell
  # Login shells stay bash but immediately `exec fish` so fish is the effective shell
  # without breaking scripts that hardcode #!/bin/bash.
  programs.fish.enable = true;
  programs.bash = {
    interactiveShellInit = ''
      if [[ $(${pkgs.procps}/bin/ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
      then
        shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=""
        exec ${lib.getExe pkgs.fish} $LOGIN_OPTION
      fi
    '';
  };
}