If you would like to run virtual machines from terminal, this is what you will need to type in, assuming that your virtual machine has been already set up.
** For Linux, use vboxmanage **
** For Mac OS X, use vBoxManage **
To find out what virtual machines you have, type
$ vBoxManage list vms
To start the virtual machine, type
$ vBoxManage startvm "name_of_virtual_machine"
If you are actually running a server that does not have GUI interface, then you might want to add the option --type headless at the end of the aforementioned command.
To view the status of the virtual machine, type
$ vBoxManage showvminfo "name_of_virtual_machine"
You may want to add | less at the end.
Also, below command will let you pause, resume, reset, power off, or save state the virtual machine:
$ vBoxManage controlvm "name_of_virtual_machine" control_option
where control_option will be one of the following: pause, resume, reset, poweroff, or savestate.
For more info, please refer to https://www.virtualbox.org/manual/ch08.html