USLEEP(3) Linux Programmer's Manual USLEEP(3)
usleep - suspend execution for interval of microseconds
#include <unistd.h> void usleep(unsigned long usec);
The usleep() function suspends execution of the calling process for usec microseconds. The sleep may be length- ened slightly by any system activity or by the time spent processing the call.
BSD 4.3
setitimer(2), getitimer(2), sleep(3), alarm(2), select(2) July 4, 1993 1