How to safely shutdown Guest OS in VirtualBox using command line

Question

I have Ubuntu 10.10 and using VirtualBox 3.2. As a Guest OS I have another Ubuntu in the VirtualBox.

I am starting Guest Ubuntu automatically using following command once my Host Ubuntu boots:

VBoxHeadless -startvm Ubuntu --vrdp on

Then I can access to it with ssh or tsclient.

Now I need to shutdown automatically Guest Ubuntu once I shutdown my Host Ubuntu. Does anybody know any safe method to automatically shutdown Guest Ubuntu with a command line? I have found out two ways one can shutdown Guest OS but I am not sure whether they are safe or not. Here are they:

VBoxManage controlvm Ubuntu acpipowerbutton

or

VBoxManage controlvm Ubuntu poweroff

Answer 1

If you open up Gnome Power management preferences, you can set what actions to take when the power button. If you set it to shut down, it will shut down gracefully when you press the virtual power button with the VBoxManage controlvm Ubuntu acpipowerbutton command.

Answer 2

This

VBoxManage controlvm Ubuntu poweroff

is equivalent to pulling the power plug on a real computer. You don't want to do this!

Use the ACPI shutdown method (check the power management setting like Egil suggests) or maybe give the save state method (savestate) a try.

Answer 3

You should poweroff your virtual Ubuntu just like you do poweroff your real hardware. From a commanline on a ssh session remotely issue:

sudo poweroff

If you want to save the machine state (similar to suspend/hibernate) use the second point in @htorque's answer.