title: Add milliseconds to timestamp (bash, unix)
body: <p>EDIT: This is apparently not possible, see Barmars answer below.</p>
  
  <p>I use the command below a lot to create a timestamp for archiving purposes. I'd like to add milliseconds to the string. Is that possible? I use this script on both osx and linux, so a solution that works on both would be nice. Are seconds ever rounded up or down with or without milliseconds? (Are minutes rounded up or down?) </p>
  
  <pre><code>date -n +%Y%m%d%H%M%S
  </code></pre>