code: func ipRunIface(iface *net.Interface, cmd string, args ...interface{}) error {
  	if err := validateInterface(iface); err != nil {
  		return err
  	}
  	_, err := ipRunOutput(cmd, args...)
  	return err
  }
docs: // ipRunIface runs the Linux ip(1) command with the specified arguments, after
  // validating the given network interface name. This function should be called
  // if the interface name is included in the arguments.