Use these binaries only if you need backward compatibility with
older udev versions. The use of /etc/dev.d/ is no longer recommended
Use explicit udev rules with RUN keys to hook into the processing.

  /etc/dev.d/ + /etc/hotplug.d/ directory multiplexing is completely
  removed from udev itself and must be emulated by calling small
  helper binaries provided by these helpers:
      make EXTRAS=extras/run_directory/
    will build udev_run_devd and udev_run_hotplugd, which can be called
    from a rule if needed:
      RUN+="/sbin/udev_run_hotplugd"
    The recommended way to handle this is to convert all the calls from
    the directories to explicit udev rules and get completely rid of the
    multiplexing. (To catch a ttyUSB event, you now no longer need to
    fork and exit 300 tty script instances you are not interested in, it
    is just one rule that matches exactly the device.)