USLEEP(3) OpenBSD Programmer's Manual USLEEP(3)NAMEusleep - suspend execution for interval of microseconds
SYNOPSIS
#include <unistd.h>
int
usleep(useconds_t microseconds);
DESCRIPTION
The usleep() function suspends execution of the calling process for
microseconds microseconds of time. System activity or time spent in
processing the call may lengthen the sleep slightly.
This routine is implemented using nanosleep(2); it requires one system
call each time it is invoked. A similar but less compatible function can
be obtained with a single select(2); such a function would not restart
after signals, and also does not interfere with other uses of
setitimer(2) (not that usleep() interferes with interval timers anymore).
RETURN VALUES
If the usleep() function returns because the requested time has elapsed,
the value returned will be zero.
If the usleep() function returns due to the delivery of a signal, the
value returned will be -1, and the global variable errno will be set to
indicate the interruption.
ERRORS
If any of the following conditions occur, the usleep() function shall
return -1 and set errno to the corresponding value.
[EINTR] usleep() was interrupted by the delivery of a signal.
[EINVAL] microseconds specified a value of 1,000,000 or more
microseconds.
NOTES
A microsecond is 0.000001 seconds.
SEE ALSOsleep(1), getitimer(2), nanosleep(2), setitimer(2), alarm(3),
sigpause(3), sleep(3), ualarm(3)STANDARDS
The usleep() function conforms to X/Open Portability Guide Issue 4.2
(``XPG4.2'').
HISTORY
The usleep() function appeared in 4.3BSD.
OpenBSD 4.9 October 24, 2008 OpenBSD 4.9
