Bugfix: child process PID is not being passed properly and child process prints failu...

Bugfix: child process PID is not being passed properly and child process prints failure message on terminate signal.

The child process PID was not being assigned because the wrong variable was being passed.

The child processes should not present error messages on exit when termination signal is received.
Make sure that when the child process exists and the main thread is disabled, exit with F_signal.