On Ubuntu 18.04, the computer suspends when pressing the power button and no user is logged on it (this behaviour is different when a user is logged in)
I've found https://askubuntu.com/a/362931/30535 but it doesn't work in my case.
Tried also to set dconf key as https://askubuntu.com/a/892108/30535 with value 'nothing' ... but this seems to be user specific, not system wide.
How could we set that the OS to ask what to do when power button is pressed? (or at least don't do anything?)