snippet from bluetooth-killswitch.c

void
bluetooth_killswitch_set_state (BluetoothKillswitch *killswitch,
                KillswitchState state)
{
    BluetoothKillswitchPrivate *priv = BLUETOOTH_KILLSWITCH_GET_PRIVATE (killswitch);
    struct rfkill_event event;
    ssize_t len;

    g_return_if_fail (state != KILLSWITCH_STATE_HARD_BLOCKED);

    memset (&event, 0, sizeof(event));
    event.op = RFKILL_OP_CHANGE_ALL;
    event.type = RFKILL_TYPE_BLUETOOTH;
    if (state == KILLSWITCH_STATE_SOFT_BLOCKED)
        event.soft = 1;
    else if (state == KILLSWITCH_STATE_UNBLOCKED)
        event.soft = 0;
    else
        g_assert_not_reached ();

    len = write (priv->fd, &event, sizeof(event));
    if (len < 0)
        g_warning ("Failed to change RFKILL state: %s",
               g_strerror (errno));
}