title: how to judge android phone is shutdown by adb tools?
body: <p>When I turn off my android phone, and then I run the &quot;adb devices&quot; command, it lists all connected devices.
  When I did not turn off the phone and then ran the same command, it returned the same result as before.
  So now I want to know if there is a way to determine whether the phone is turned off.</p>