nanosleep.2 (2010 09)

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nanosleep(2) nanosleep(2)
NAME
nanosleep() - high resolution sleep
SYNOPSIS
#include <time.h>
int nanosleep(
const struct timespec *rqtp,
struct timespec *rmtp
);
DESCRIPTION
The nanosleep() function causes the current thread to be suspended from execution until either the
time interval specified by the rqtp
argument has elapsed, or a signal is delivered to the calling thread
and its action is to invoke a signal-catching function or to terminate the process. The suspension time
may be longer than that requested because the argument value is rounded up to an integer multiple of
the sleep resolution or because of the scheduling of other activity by the system. However, with the
exception of the case of being interrupted by a signal, the suspension time will not be less than the time
specified by
rqtp, as measured by the system clock,
CLOCK_REALTIME
.
The use of the
nanosleep() function has no effect on the action or blockage of any signal.
RETURN VALUE
If the
nanosleep() function returns because the requested time has elapsed, its return value is zero.
If the
nanosleep() function returns because it has been interrupted by a signal, the function returns a
value of − 1 and sets errno to indicate the interruption. If the
rmtp argument is non-NULL, the
timespec structure referenced by it is updated to contain the amount of time remaining in the interval
(the requested time minus the time actually slept). If the
rmtp argument is NULL, the remaining time is
not returned.
If
nanosleep() fails, it returns a value of −1 and sets errno to indicate the error.
ERRORS
If any of the following conditions occur, the
nanosleep() function returns −1 and sets errno (see
errno (2)) to the corresponding value:
[EFAULT] The
rqtp or rmtp arguments specify an invalid address.
[EINTR]
nanosleep() was interrupted by a signal.
[EINVAL] The
rqtp argument specified a nanosecond value less than zero or greater than or
equal to 1000 million.
[ENOSYS] The function
nanosleep() is not supported by this implementation.
EXAMPLES
Suspend execution of the current thread for half a second:
#include <time.h>
#include <errno.h>
struct timespec interval, remainder;
interval.tv_sec = 0;
interval.tv_nsec = 500000000;
if (nanosleep(&interval, &remainder) == -1) {
if (errno == EINTR) {
(void)printf("nanosleep interrupted\n");
(void)printf("Remaining secs: %d\n", remainder.tv_sec);
(void)printf("Remaining nsecs: %d\n", remainder.tv_nsec);
}
else perror("nanosleep");
}
AUTHOR
nanosleep was derived from the proposed IEEE POSIX P1003.4 Standard, Draft 14.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1