Hello,
I’m familiar with OpenHAB 1.x where you can go to the start.sh and execute there, and you can see what OpenHAB is doing and see MQTT events change item states.
I just did an install using apt-get, and use systemctl to start. Where can I see a stream of OpenHAB events and errors?
Thanks!
I’m assuming you mean in openHAB 2?
For bootup errors, it’s best to check the systemctl journal:
sudo journalctl -u openhab2 -b
For errors that happen after openHAB has started you can check the logs at /var/log/openhab2 events such as the item changing states will be in events.log everything else goes in openhab2.log.
You may want to have a look into the Karaf console. Read first the documentation, then use it and learn to love it. I have always two sessions opened one with the console and one where I edit the files. 
And then use
log:tail