title: How to use adb shell controll android app?
body: <p>I am trying to develop an android demo.I want to use command in adb shell to make the demo do what I want.I may need an shell file.</p>
  
  <p>The result I want like this.</p>
  
  <pre><code>root@device:/ # &lt;shell&gt; log "hello world" 
  </code></pre>
  
  <p>then my app console "hello world" at logcat.</p>
  
  <p>but I don't know how to connect them.</p>