gistfile1.txt

let
  commitRev = "cb2cdab71368885ce6408b3ad7cfcf544a8c38a0"; # 19.09 on 2019-09-12

  nixpkgs = builtins.fetchTarball {
    url = "https://github.com/NixOS/nixpkgs/archive/${commitRev}.tar.gz";
    sha256 = "02vyx2ccrfqxz7ndlfww1ivqbq1qlmglq5690r6nvmylcm976dqw";
  };

  pkgs = import nixpkgs { config = {}; };

in

pkgs.mkShell {

  buildInputs = [ pkgs.nixops ];

  shellHook = ''
    export NIX_PATH="nixpkgs=${nixpkgs}"
    export NIXOPS_DEPLOYMENT="mail"
  '';

}