default.nix

let 
  pkgs = import <nixpkgs> {};

  d = {stdenv}:
    stdenv.mkDerivation {
      name = import (pkgs.runCommand "hello-output" {} ''
        ${pkgs.hello}/bin/hello -g '"d-name"'> $out
      '');
      buildCommand = "touch $out";
    };

in pkgs.callPackage d {}