Running VirtualBox in Headless Mode

You can list all virtual machines that you have configured with:
# VBoxManage list vms
"TestVm" {4176c387-a851-4cca-8b2e-d6246c04c388}

To start a Virtual Machine in headless mode using VirtualBox:
# VBoxManage startvm TestVm --type headless

To Power off a Virtual Machine that is running in VirtualBox:
# VBoxManage controlvm TestVm poweroff