if sudo virsh list | grep instack; then
instack_mac=$(sudo virsh domiflist instack | grep default | \
grep -Eo "[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:[0-9a-f]+")
if sudo virsh list | grep instack; then
instack_mac=$(sudo virsh domiflist instack | grep default | \
grep -Eo "[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:[0-9a-f]+")