VirtualBox is able to automatically install a guest by providing the installation medium as well as a few parameters like the name of the default user.
To perform an unattended guest installation, a VM has to be prepared. A VM can be created using the GUI as described in Section 1.7, “Creating your first virtual machine” or by using VBoxManage as described in Section 8.7, “VBoxManage createvm”. In general it's sufficient to chose the type of the guest operating system and to use the proposed defaults for that operating system. See the following sections on how to change the VM settings for certain needs.
After the VM was created, the VM has to be prepared for unattended guest execution use VBoxManage, see Section 8.42, “VBoxManage unattended”. During this step VirtualBox scans the installation medium and changes certain parameters for a seamless installation as a guest running on VirtualBox.
Once the preparation phase was successfully finished, the VM can be started either from the GUI or from VBoxManage, see Section 8.12, “VBoxManage startvm”. The VM will now perform the automatic installation. Please note that the boot order was changed during the preparation phase by giving the virtual hard disk the highest priority. As the disk is normally empty before an automatic installation is started, the VM will boot from the virtual DVD drive as next available boot medium and the installation will start. If, for some reason, the virtual hard disk contains a bootable operating system then the installation will not start unless the boot order was manually changed by pressing F12 during the BIOS splash screen.