title: Convert GMT datetime string to utc epoch in 1000s of large csv files
body: <p>I have 1000s of csv files that consist of millions of rows that have integers, floats, nullable integers, and 2 types of GMT datetime string formats. Below is an example of such a row in one of the files:</p>
  
  <p><code>2/20/2016 3:25,3,,87,340.3456,5/18/2013,5/19/2014,4,6</code></p>
  
  <p>I'm interested in the quickest way to convert (in place) both types of GMT datetime formatted strings into UTC epochs.</p>
  
  <p>For example, the above row would be converted into:</p>
  
  <p><code>1455938740,3,,87,340.3456,1368835200,1400457600,4,6</code></p>
  
  <p>Suppose the files are isolated, so all can be gathered by <code>*.csv</code></p>
  
  <p>Is there a way I could do this with linux commands? If not, what would you suggest then?</p>