 [det]fork_exec(+Command)Fork (as fork/1) and exec (using exec/1) 
the child immediately. This behaves as the code below, but bypasses the 
check for the existence of other threads because this is a safe 
scenario.
[det]fork_exec(+Command)Fork (as fork/1) and exec (using exec/1) 
the child immediately. This behaves as the code below, but bypasses the 
check for the existence of other threads because this is a safe 
scenario.
fork_exec(Command) :-
      (   fork(child)
      ->  exec(Command)
      ;   true
      ).