usleep - suspend execution for microsecond intervals
int usleep(unsigned long usec); /* SUSv2 */
The usleep() function suspends execution of the
calling process for usec microseconds. The sleep may
be lengthened slightly by any system activity or by the time
spent processing the call.
None (BSD). Or: 0 on success, -1 on error
Interrupted by a signal.
usec is not smaller than 1000000. (On systems where
that is considered an error.)
BSD 4.3. The SUSv2 version returns int, and this is also the
prototype used by glibc 2.2.2. Only the EINVAL error return
is documented by SUSv2.
The interaction of this function with SIGALRM and other
timer functions such as sleep(), alarm(),
setitimer(), nanosleep() is unspecified. This
function is obsolete. Use nanosleep(2) or
alarm(2), getitimer(2), nanosleep(2),