title: How to stop all background processes in android?
body: <p>I hope to stop all backgroud processes. </p>
  
  <p>I got to know that <code>adb shell am kill-all</code> may do this job. I exit one application by pressing BACK, </p>
  
  <p>then I enter <code>adb shell am kill-all</code>, However, I find the process by entering <code>adb shell ps | grep packagename</code>. </p>
  
  <p>Does <code>adb shell am kill-all</code> really work?</p>