title: What does -f mean in bash
body: <p>I was looking at how to use <a href="http://gunicorn-docs.readthedocs.org/en/latest/deploy.html#runit" rel="noreferrer">runit to run gunicorn</a>. I was looking at the bash file and I don't know what <code>-f $PID</code> does in</p>
  
  <pre><code>#!/bin/sh
  
  GUNICORN=/usr/local/bin/gunicorn
  ROOT=/path/to/project
  PID=/var/run/gunicorn.pid
  
  APP=main:application
  
  if [ -f $PID ]; then rm $PID; fi
  
  cd $ROOT
  exec $GUNICORN -c $ROOT/gunicorn.conf.py --pid=$PID $APP
  </code></pre>
  
  <p>Google is useless in this case because searching for flags is useless</p>