I have started an instance of Ubuntu VM.

However I do not know the IP of this VM. The IP of the VM is assigned by the DHCP server. I could have logged into AirPort to find out, or just log in via the Ubuntu instance’s virtual screen.

But being a lazy bastard I would rather be able to find out this bit of information without leaving my shell (which has an active ssh session into the host PC)

Then I discover this cool feature of VirtualBox: guestcontrol

So it is what I did: