usleep - suspend execution for interval of microseconds
#include <unistd.h> void usleep(unsigned long usec));
The usleep() function suspends execution of the calling pro- cess for usec microseconds. The sleep may be lengthened slightly by any system activity or by the time spent pro- cessing the call.
setitimer(2), getitimer(2), sleep(3), alarm(2), select(2)