The
usleep() function suspends execution of the calling process until either the number of microseconds specified by
microseconds have elapsed or a signal is delivered to the calling process and its action is to invoke a signal catching function or to terminate the process. The suspension time may be longer than requested due to the scheduling of other activity by the system.
The
microseconds argument must be less than 1,000,000. If the value of
microseconds is 0, then the call has no effect.