nanosleep(2)                                                   nanosleep(2)




 NAME    [Toc]    [Back]
      nanosleep() - high resolution sleep

 SYNOPSIS    [Toc]    [Back]
      #include <time.h>

      int nanosleep(
           const struct timespec *rqtp,
           struct timespec *rmtp
      );

 DESCRIPTION    [Toc]    [Back]
      The nanosleep() function causes the current process 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 process
      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.  But, except for 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    [Toc]    [Back]
      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    [Toc]    [Back]
      If any of the following conditions occur, the nanosleep() function
      returns -1 and sets errno (see errno(2)) to the corresponding value:

           [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.





 Hewlett-Packard Company            - 1 -   HP-UX 11i Version 2: August 2003






 nanosleep(2)                                                   nanosleep(2)




           [ENOSYS]    The function nanosleep() is not supported by this
                       implementation.

           [EFAULT]    The rqtp or rmtp arguments specify an invalid
                       address.

 EXAMPLES    [Toc]    [Back]
      Suspend execution of the current process 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    [Toc]    [Back]
      nanosleep was derived from the proposed IEEE POSIX P1003.4 Standard,
      Draft 14.

 SEE ALSO    [Toc]    [Back]
      clocks(2), timers(2), sleep(3C).

 STANDARDS CONFORMANCE    [Toc]    [Back]
      nanosleep(): POSIX.4


 Hewlett-Packard Company            - 2 -   HP-UX 11i Version 2: August 2003