title: How can I iterately process all files under one directory using mrjob
body: <p>I am using mrjob to process a batch of files and get some statistics. I know I can run mapreduce job on a single file, like</p>
  
  <pre><code>python count.py &lt; some_input_file &gt; output
  </code></pre>
  
  <p>But how can I feed a directory of files to the script? The file directory structure is like this <code>folder/subfolders/files</code>, is there any suggestion?</p>