title: How to perform an action when a remote (Http) file changed?
body: <p>I want to create a script that checks an URL and perform an action (download + unzip) when the "Last-Modified" header of the remote file changed. I thought about fetching the header with curl but then I have to store it somewhere for each file and perform a date comparison. </p>
  
  <p>Does anyone have a different idea using (mostly) standard unix tools?</p>
  
  <p>thanks</p>