BigShell

Bring your shell of choice to mkShell with a simple wrapper

Basic Example

Edit flake.nix

{
  inputs = {
    utils.url = "github:numtide/flake-utils";
    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
    bigShell.url = "github:chaoky/bigShell";
  };
  outputs =
    {
      utils,
      nixpkgs,
      bigShell,
      ...
    }:
    utils.lib.eachDefaultSystem (
      system:
      let
        pkgs = import nixpkgs { inherit system; };
      in
      {
        devShell = bigShell.mkShell {
          inherit pkgs;
          # supports bash, zsh and fish
          # use "auto" to impure read from $SHELL
          shell = "fish";
          shellHook = ''
            echo "using $SHELL_NAME"
          };
        };
      }
    );
}

Enter the shell

nix develop --impure

Advanced Example

...
{
  devShell = bigShell.mkShell {
    inherit pkgs;
    shell = "fish";
    buildInputs = with pkgs; [ fnm ];
    shellHook = ''
      echo "using $SHELL_NAME"
    '';
    bashHook = ''
      eval "$(fnm env --use-on-cd --shell bash)"
    '';
    zshHook = ''
      eval "$(fnm env --use-on-cd --shell zsh)"
    '';
    fishHook = ''
      fnm env --use-on-cd --shell fish | source
    '';
  };
}

why not use flake from direnv

direnv only exports and clears environment variables, it'll not work for more advanced shell features like in the example above, I still use direnv to manage my secrets and environment variables

auto enter shell

Add something similar to this zsh script to your shell init file to automatically enter the development environment

# auto nix develop
nix_flake_cd() {
  if [[ -f "flake.nix" && -z "$NIX_SHELL_LEVEL" ]]; then
    export NIX_SHELL_LEVEL=1
    nix develop --impure
    export NIX_SHELL_LEVEL=
  fi
}

autoload -U add-zsh-hook
add-zsh-hook chpwd nix_flake_cd && nix_flake_cd

todo

• support more sheels
• add shell hooks for popular packages
• introduce an auto shell enter similar to dirven