title: How to use ADB Shell when Multiple Devices are connected? Fails with "error: more than one device and emulator"
body: <pre><code>$ adb --help
  </code></pre>
  <hr />
  <pre><code>-s SERIAL  use device with given serial (overrides $ANDROID_SERIAL)
  </code></pre>
  <hr />
  <pre><code>$ adb devices
  List of devices attached 
  emulator-5554   device
  7f1c864e    device
  </code></pre>
  <hr />
  <pre><code>$ adb shell -s 7f1c864e
  error: more than one device and emulator
  </code></pre>