Returns the current time (in seconds and nanoseconds) for the
    specified clock.

    This function is supported on OpenVMS Integrity servers and
    Alpha only.

    Format

      #include  <time.h>

      int clock_gettime  (clockid_t clock_id, struct timespec *tp);

1 - Arguments

 clock_id

    The clock type used to obtain the time for the clock that is
    set. The CLOCK_REALTIME clock is supported and represents the
    TIME-OF-DAY clock for the system.

 tp

    A pointer to a timespec data structure.

2 - Description

    The clock_gettime function returns the current tp value for the
    specified clock, clock_id.

    On success, the function returns 0.

    On failure, the function returns -1 and sets errno to indicate
    the error.

    See also clock_getres, clock_settime, time, and ctime.

3 - Return Values

    0                  Indicates success.
    -1                 Indicates failure; errno is set to the
                       following value:

                       o  EINVAL - The clock_id argument does not
                          specify a known clock, or the tp argument
                          specifies a nanosecond value less than 0 or
                          greater than or equal to 1 billion.