usleep -- suspend process execution for an interval measured in microseconds
Standard C Library (libc, -lc)
The usleep() function suspends execution of the calling process until
either microseconds microseconds have elapsed or a signal is delivered to
the process and its action is to invoke a signal-catching function or to
terminate the process. System activity may lengthen the sleep by an
This function is implemented using nanosleep(2) by pausing for
microseconds microseconds or until a signal occurs. Consequently, in
this implementation, sleeping has no effect on the state of process
timers, and there is no special handling for SIGALRM.
The usleep() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
The usleep() function will fail if:
[EINTR] A signal was delivered to the process and its action
was to invoke a signal-catching function.
The usleep() function appeared in 4.3BSD.
FreeBSD 5.2.1 February 13, 1998 FreeBSD 5.2.1 [ Back ]