Add to ~/.tmux.conf this line

set-window-option -g mode-keys vi

To start a machine headless (without the VirtualBox windows around) use

$ VBoxManage startvm centos1 –type headless

where centos1 is the name of my virtual machine. To list all the virtual machines use

$ VBoxManage list vms

This works on Windows with cmd too, but you have to move to the VirtualBox directory at first, like this

cd C:\Program Files\Oracle\VirtualBox

VBoxManage modifyhd “C:\Users\Chris\VirtualBox VMs\Windows 7\Windows 7.vdi” –resize 81920