Is there an OS command I can run to determine if running inside a Xen based virtual machine

Question

Is there an OS command I can run from within a Xen based virtual machine to tell me that it is a virtual box rather than a physical box - I heard that the kernel had some self a

Answer 1

Try file /sys/hypervisor/uuid.

1. It does not exist -> Not related to XEN.
2. It does exist, and is full of 0-s -> It is a XEN Dom0
3. It does exist, and has a not-0 values -> It is a DomU

This requires of course, that /sys is mounted and populated...