Start a virtual machine. More information: https://www.virtualbox.org/manual/ch08.html#vboxmanage-startvm.
VBoxManage startvm vm_name|uuid
VBoxManage startvm vm_name|uuid --type headless|gui|sdl|separate
VBoxManage startvm vm_name|uuid --password path/to/password_file
VBoxManage startvm vm_name|uuid --password-id password_id
VBoxManage startvm vm_name|uuid --put-env=name=value