title: How to insert a variable inside bash -c command
body: <p>I can do the following:</p>
  
  <pre><code>$ FOO="text"
  $ echo $FOO
  $ text
  </code></pre>
  
  <p>But how can I wrap it inside <code>bash -c</code> construct? I tried this but failed:</p>
  
  <pre><code>$ FOO="text"
  $ bash -c 'echo $FOO'
  $ # return nothing
  </code></pre>
  
  <p>The reason I ask this because I need to execute another 3rd party code that need to be wrapped inside <code>bash -c</code></p>