WaitAndFork stalls the invoking process and forks child processes when signals are sent to it from an external source. Forked child processes will provide a return value ofEWaitAndForkResult::Child, while the parent process will not return until IsEngineExitRequested() is true (EWaitAndForkResult::Parent) or there was an error (EWaitAndForkResult::Error) The signal the parent process expects is platform-specific (i.e. SIGRTMIN+1 on Linux).