title: Why does the "at" command always warn me that commands will be executed via sh?
body: <p>Every time I use the "at" command, I get this message:</p>
  
  <pre><code>warning: commands will be executed using /bin/sh
  </code></pre>
  
  <p>What is it trying to warn me about? More importantly, how do I turn the warning off?</p>