int pcntl_sigwaitinfo ( array $set [, array &$siginfo ] )
The pcntl_sigwaitinfo() function suspends execution of the calling script until one of the signals given in set are delivered. If one of the signal is already pending (e.g. blocked by pcntl_sigprocmask()), pcntl_sigwaitinfo() will return immediately.
On success, pcntl_sigwaitinfo() returns a signal number.