title: Evaluating variables in a string
body: <p>The last line in this script won't work as I expect:</p>
  
  <pre><code>myfile="afile.txt"
  mycmd='cat $myfile'
  eval $mycmd
  echo eval $mycmd
  </code></pre>
  
  <p>Here echo prints 'eval cat $myfile'. How can I print 'eval cat afile.txt'?</p>