title: Store a string in a shared place, accessible to a set of applications only
body: <p>Imagine these applications:</p>
  
  <ol>
  <li><code>com.example</code></li>
  <li><code>com.example.app1</code></li>
  <li><code>com.example.app2</code></li>
  </ol>
  
  <p>One solution is to use <code>android:sharedUserId='com.example'</code> in both <code>app1</code> and <code>app2</code> and use the same <strong>certificate</strong> to sign all packages, so that all of them can access the shared preferences of the <code>com.example</code>.</p>
  
  <p>However, this has a drawback. <code>app1</code> and <code>app2</code> can share something only and if only <code>com.example</code> is installed first.</p>
  
  <p>Is there a way around this, so that applications <code>app1</code> to <code>appN</code> can access a shared place, only limited to them, without the need for a central useless package to be used only as a shared Linux username?</p>