virtualbox.org

I would like to keep a VM on a USB device, and be able to run it without touching the host
hard disk. How can I do this? Are there command line flags I can pass to VirtualBox
to tell it where the .vdi and .xml are? Linux host, Linux guest. Thanks.

If the whole config is on the stick, so it includes VirtualBox.xml, then you can start VB using the environmental variable before starting it. E.g. launch it with VBOX_USER_HOME=/media/disk/vm VirtualBox. You have to make sure the paths in the XML file are correct before staring VB, else the VMs will be inaccessible.