getting nanoseconds in linux

[Yoda]

The function is clock_gettime

Output:
strace date +%Y-%m-%dT%H:%M:%S.%N 2>&1 | grep clock
clock_gettime(CLOCK_REALTIME, {1506547158, 42515000}) = 0

URL: http://pubs.opengroup.org/onlinepubs/790...ttime.html