open Unix

let () =
  let now = gettimeofday () in
  Printf.printf "%f\n" now;

  (* Get seconds since Unix epoch *)
  let seconds = int_of_float now in
  Printf.printf "%d\n" seconds;

  (* Get milliseconds since Unix epoch *)
  let milliseconds = int_of_float (now *. 1000.) in
  Printf.printf "%d\n" milliseconds;

  (* Get nanoseconds since Unix epoch *)
  let nanoseconds = int_of_float (now *. 1e9) in
  Printf.printf "%d\n" nanoseconds;

  (* Convert seconds back to time *)
  let time_from_seconds = localtime (float_of_int seconds) in
  Printf.printf "%s\n" (string_of_tm time_from_seconds);

  (* Convert nanoseconds back to time *)
  let time_from_nanos = localtime (float_of_int seconds) in
  Printf.printf "%s\n" (string_of_tm time_from_nanos)