If you are running a VirtualBox virtualization software with a multiple virtual
machines, sometimes you may want to list available virtual machines. This is
especially useful if you are running your virtual machines in a headless mode.
To display available virtual machines the VirtualBox gives you two options to list
by using VBoxManage command:
List all available virtual machines
$ VBoxManage list vms
List all running available virtual machines
$ VBoxManage list runningvms