I am using several Raspberry Pi 3B's and need to understand their relationship with real-time. One just boots to Ubuntu Mate desktop 1.16.2, and when the GUI finishes installing, the clock is set correctly, presumably from its internet connection. The others (call them blind) use the same OS, but have no display, keyboard or mouse, and I load the application on startup from /etc/rc.local (with & on the command so the OS loading can continue.)
The question is this: When the application starts on the blind processors, the time appears randomly set. Is there some way to pause at the beginning of the application until the clock connection has been made and the real-time clock set?