power_button
if (power_button == NULL) {
power_button = mevent_add(SIGTERM, EVF_SIGNAL,
if (power_button != NULL) {
mevent_delete(power_button);
power_button = NULL;
static struct mevent *power_button;
TYPE_EXACT, ILEVEL_0, power_button,
static int power_button(di_minor_t minor, di_node_t node);