10 * * * * /usr/sbin/ntpdate pool.ntp.org >/dev/null 2>&1
The idea is to sync time every 10 minutes.
However im waiting now for 15 minutes and
still returns empty.
Is this cron running?, if yes where can i find prove?
You told it to run every hour at the 10th minute, not every 10 minutes.
Change '10' to '*/10' to get the behavior you are asking for. Or, you could expand it into '0,10,20,30,40,50'
That said, do not do this. Jumping your clock can cause all kinds of nastyness. Set up ntpd properly, which actually alters the lengths of seconds to bring your clock into line without the issues associated with just changing the clock.
What you really want is
This is a broken way to set your time. Do it right and just set up ntpd.
Running ntpdate manually via cron like causes the clock to jump around and this could possibly cause issues for time-sensitive applications. By running ntpd, you avoid this as ntpd gradually slews the system time around to correct it.