title: pgrep exact matching with a PID file
body: <p>I have a process ID stored in a .pid file.</p>
  
  <p>I want the <code>pgrep</code> command to find out whether that process is running or not. I tried using the flags <code>pgrep -xF file.pid</code> but I'm still getting a regex match (which is what I do not want).</p>
  
  <p>Is there any way to get an exact match?</p>
  
  <p>Thank you.</p>