NAME

       nanosleep — high resolution sleep

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <time.h>

       int
       clock_nanosleep(clockid_t clock_id, int flags, const struct timespec *rqtp, struct timespec *rmtp);

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

DESCRIPTION

       If  the TIMER_ABSTIME flag is not set in the flags argument, then clock_nanosleep() suspends execution of
       the calling thread 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 clock used to measure the time is specified by the clock_id argument.

       If  the TIMER_ABSTIME flag is set in the flags argument, then clock_nanosleep() suspends execution of the
       calling thread until either the value of the  clock  specified  by  the  clock_id  argument  reaches  the
       absolute  time  specified  by  the rqtp argument, or a signal is delivered to the calling process and its
       action is to invoke a signal-catching function or to terminate the process.  If, at the time of the call,
       the time value specified by rqtp is less than or equal to the time value of  the  specified  clock,  then
       clock_nanosleep() returns immediately and the calling thread is not suspended.

       The  suspension  time may be longer than requested due to the scheduling of other activity by the system.
       An unmasked signal will terminate the sleep early, regardless of the SA_RESTART value on the interrupting
       signal.  The rqtp and rmtp arguments can point to the same object.

       The following clock_id values are supported:

             CLOCK_MONOTONIC
             CLOCK_MONOTONIC_FAST
             CLOCK_MONOTONIC_PRECISE
             CLOCK_REALTIME
             CLOCK_REALTIME_FAST
             CLOCK_REALTIME_PRECISE
             CLOCK_SECOND
             CLOCK_UPTIME
             CLOCK_UPTIME_FAST
             CLOCK_UPTIME_PRECISE

       The nanosleep() function behaves like clock_nanosleep() with a clock_id argument  of  CLOCK_REALTIME  and
       without the TIMER_ABSTIME flag in the flags argument.

RETURN VALUES

       These functions return zero when the requested time has elapsed.

       If  these  functions  return  for any other reason, then clock_nanosleep() will directly return the error
       number, and nanosleep() will return -1 with the global variable errno set to indicate the  error.   If  a
       relative  sleep  is interrupted by a signal and rmtp is non-NULL, the timespec structure it references is
       updated to contain the unslept amount (the request time minus the time actually slept).

ERRORS

       These functions can fail with the following errors.

       [EFAULT]           Either rqtp or rmtp points to memory that is not a valid part of the  process  address
                          space.

       [EINTR]            The function was interrupted by the delivery of a signal.

       [EINVAL]           The rqtp argument specified a nanosecond value less than zero or greater than or equal
                          to 1000 million.

       [EINVAL]           The flags argument contained an invalid flag.

       [EINVAL]           The clock_id argument was CLOCK_THREAD_CPUTIME_ID or an unrecognized value.

       [ENOTSUP]          The  clock_id  argument  was  valid  but  not  supported  by  this  implementation  of
                          clock_nanosleep().

SEE ALSO

       clock_gettime(2), sigaction(2), sleep(3)

STANDARDS

       These functions conform to IEEE Std 1003.1-2008 (“POSIX.1”).

Debian                                           March 17, 2017                                     NANOSLEEP(2)