VirtualBox

You're doing it wrong, use LXC instead.

List your VMs:

vboxmanage list vms
vboxmanage list runningvms

Start a box from the command line.

vboxmanage startvm <vmname> --type headless

Crap, what IP is it running on? And other questions:

vboxmanage guestproperty enumerate <vmname>

Stop it:

vboxmanage controlvm <vmname> acpipowerbutton

You can use the UUID of the VM instead of the name, above.