let run () =
  print_string Common.header;
  Common.meat_print "PREPARING RITUAL GROUND..";
  let ( >>= ) = Result.bind in
  let ( >|= ) = Fun.flip Result.map in
  let tmpdir = Filename.temp_dir "meat-chew" "" in
  let meats = Unix.getenv "MEATS" in
  let hostname = Unix.gethostname () in
  let nix_conf_target =
    meats ^ "/entry.nix -A nixosConfigurations." ^ hostname
    ^ {|'.config.environment.etc."nix/nix.conf"'|}
  in
  let build_target =
    meats ^ "/entry.nix -A nixosConfigurations." ^ hostname
    ^ ".config.system.build.toplevel"
  in
  ( Common.do_cmd ~args:false
    @@ "nix-build --log-format internal-json -v --out-link " ^ tmpdir
    ^ "/nix.conf " ^ nix_conf_target ^ " |& nom --json"
  >>= fun () ->
    Common.meat_print "CONSUMING MEATS..";
    Common.do_cmd ~args:false
    @@ "NIX_USER_CONF_FILES=" ^ tmpdir
    ^ "/nix.conf nix-build --log-format internal-json -v --out-link " ^ tmpdir
    ^ "/build " ^ build_target ^ " |& nom --json"
  >>= fun () ->
    Common.do_cmd ~args:false @@ "dix /nix/var/nix/profiles/system " ^ tmpdir
    ^ "/build"
  >>= fun () ->
    Common.do_cmd ~args:false
    @@ "sudo nix-env --set -p /nix/var/nix/profiles/system " ^ tmpdir
    ^ "/build && " ^ tmpdir ^ "/build/bin/switch-to-configuration switch"
  >|= fun () ->
    Unix.unlink @@ tmpdir ^ "/nix-conf";
    Unix.unlink @@ tmpdir ^ "/build" )
  |> ( function
  | Error _ -> print_string "FAILED TO CONSUME MEATS."
  | _ -> () );
  print_string Common.footer