title: Is "escapeshellarg" safe enough?
body: <p>Scenario:</p>
  
  <ol>
  <li><p>user enters video url</p></li>
  <li><p>php downloads video with <code>exec( "youtube-dl " . escapeshellarg($url) );</code></p></li>
  </ol>
  
  <p>Question:</p>
  
  <p>Is it safe enough?</p>
  
  <p>Thanks!</p>