If a man runs away from home and his cell phone is not turned off, how can he know his location?

If it's a smartphone, it's easy. Send a positioning command to your mobile phone with another mobile phone, and you will receive a short message telling you the specific location, such as "West of XX base station 100 meters". You can also lock and delete personal data, such as address books. If it is not a smart machine, it will be very difficult. The public security organs have the ability to find the place, but you are not a criminal case and they will not help you.