title: uevent sent from kernel to user space (udev)
body: <p>I knew that udev plays on the linux system and it receives uevents sent from the kernel through netlink socket.</p>
  
  <p>However, my questions are:</p>
  
  <ol>
  <li><p>How kernel sends out the event ? It must be something triggered by adding/removing device and then sends out events to udev. How does kernel do this? (Is there any code example I can find? )</p></li>
  <li><p>udev receives these uevents only through netlink socket. This is the only way that udev does it. Is this correct?</p></li>
  <li><p>When uevent is sent out from the kernel, I knew it can do broadcast. However, Can it do unicast?</p></li>
  </ol>
  
  <p>Thanks for any feedback.</p>