title: How to find the timestamp of the latest modified file in a directory (recursively)?
body: <p>I'm working on a process that needs to be restarted upon any change to any file in a specified directory, recursively.</p>
  
  <p>I want to avoid using anything heavy, like <a href="http://man7.org/linux/man-pages/man7/inotify.7.html" rel="noreferrer"><code>inotify</code></a>. I don't need to know which files were updated, but rather only whether or not files were updated at all. Moreover, I don't need to be notified of every change, but rather only to know if any changes have happened at a specific interval, dynamically determined by the process.</p>
  
  <p>There has to be a way to do this with a fairly simple bash command. I don't mind having to execute the command multiple times; performance is not my primary concern for this use case. However, it would be preferable for the command to be as fast as possible.</p>
  
  <p>The only output I need is the timestamp of the last change, so I can compare it to the timestamp that I have stored in memory.</p>
  
  <p>I'm also open to better solutions.</p>