title: Detecting Perforce unopened modified files
body: <p>I'm trying to figure out a way to detect files that are not opened for editing but have nevertheless been modified locally. <code>p4 fstat</code> returns a value <code>headModTime</code> for any given file, but this is the change time in the depot, which should not be equal to the filesystem's <code>stat</code> last modified time.</p>
  
  <p>I'm hoping that there exists a more lightweight operation than backing up the original file, forcing a sync of the file, and then running a diff. Ideas?</p>