basic nix-shell that imports env variables from a separate file

env.sh

# comment
MY_VAR_1=aaa
MY_VAR_2=bbb

shell.nix

{ pkgs ? import <nixpkgs> {} }:

pkgs.mkShell {
  buildInputs = with pkgs; [
    nodejs-18_x
  ];

  shellHook = ''
    # Mark variables which are modified or created for export.
    set -a
    #source env.sh
    # or to make it relative to the directory of this shell.nix file
    source ${toString ./env.sh}
    set +a
  '';

}