This can be used to reset forgotten root passwords in paravirtualised VM’s running on the Xen hypervisor.
1. Identify target VM name.
virsh list --all
2. Shutdown the target VM.
virsh shutdown vm-name-goes-here
3. Start the VM back up again in console mode.
xm create -c vm-name-goes-here
4. Quickly stop the boot process on the grub menu and hit the a key on the default kernel. Once the kernel parameters appear, append the number 1 to the end of the line. Then hit enter to continue with the VM boot.
5. You should then be dropped into a single user mode console, allowing you to reset the password as you would on a physical host.
6. Enter this command to change the root password, you have to enter the new password twice when prompted onscreen.