How to sync time on RPi?

[mbyrne29]

Potential issue:

• If the Raspberry Pi is off for a while, the clock drifts
• The system date/time (see via date command) syncs via the internet -> if hotspot doesn't have internet connections, the time won't be right
• This shouldn't be a major problem on its own, but it could be really annoying if the Pi gets connected to the internet in the middle of a sniffer recording

Potential solutions:

• Use relative time to sync between GPS and BLE data -> this may mean having to calculate the relative time for the GPS (tshark does this automatically)
• Use GPS time to sync Raspberry Pi time -> a little shell script that takes the first reading and uses it to set the time via the date -s command?
• Something else?