sudo systemctl stop virtualgps <--- This stops a running virtualgps service
sudo systemctl disable virtualgps <--- This prevents the virtualgps service from starting at boot time, but it doesn't stop an already running virtualgps service.

In case you have problems getting a fix from your GPS, then it's a good idea to put your usual home location into /etc/location.conf

That way, if you can't get a fix, then you can start the virtualgps service and use it with GPSD as normal.

To start:
sudo systemctl start virtualgps

You don't need to enable virtualgps in order to start it, that just makes it start automatically at boot time.

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