select your vm:
xe vm-list
detect id of dom of its vm:
xe vm-param-list uuid=8e2dd6ac-4883-0e6e-5cce-afbf214fa916 | grep dom-id
read vnc port by that dom_id:
xenstore-read /local/domain/18/console/vnc-port
select your vm:
xe vm-list
detect id of dom of its vm:
xe vm-param-list uuid=8e2dd6ac-4883-0e6e-5cce-afbf214fa916 | grep dom-id
read vnc port by that dom_id:
xenstore-read /local/domain/18/console/vnc-port