title: Extract Value of CSV Column to Add Attribute
body: <p>I'm working with some CSVs in NiFi and my pipeline is producing some duplicates. As a result, I'd like to use the <code>DetectDuplicate</code> processor, but in order to do this I need to have some attribute that it can compare against to detect duplication. I have an ExtractText processor, and I'd like to use regex to get the value in the <code>SHA1_BASE16</code> column. </p>
  
  <p>I tried the following regex string (suggested by a friend, I don't totally understand it) on the CSV below but highlighted the incorrect fields and some extraneous stuff. How can I get it to capture <em>only</em> the <code>SHA1_BASE16</code> value? </p>
  
  <p><strong>RegEx</strong></p>
  
  <pre><code>^[^,]*,[^,]*,[^,]*,[^,]*,[^,]*,([^,]*),[^,]*,[^,]*,[^,]*,[^,]*,[^,]*,([^,]*),[^,]*,[^,]*,([^,]*)\S*
  </code></pre>
  
  <p><strong>CSV</strong></p>
  
  <pre><code>"USER_JID","CREATED_AT","UPLOAD_TIME","SHA1_BASE32","SHA1_BASE16","HASH_SOURCE","MESSAGE_TYPE","IPV4"
  "dreynolds","1932/04/01 20:23:35 UTC","2016/12/28 20:23:11 UTC","72F20077A79A0D4D90F4C0669FB6EA4BC5953293","FB1D928B83DEBCD2B2E53DF4C8D4C2AF99EB81E0","HOLLYWOOD","TWITTER","123.123.123.123"
  </code></pre>
  
  <p><strong>Actual Output</strong></p>
  
  <pre><code>Match 1
  Full match  0-291   "USER_JID","CREATED_AT","UPLOAD_TIME","SHA1_BASE32","SHA1_BASE16","HASH_SOURCE","MESSAGE_TYPE","IPV4...
  Group 1.    66-79   "HASH_SOURCE"
  Group 2.    209-251 "FB1D928B83DEBCD2B2E53DF4C8D4C2AF99EB81E0"
  Group 3.    274-291 "123.123.123.123"
  </code></pre>
  
  <p><strong>Expected Output</strong></p>
  
  <pre><code>Match 1
  Full match  0-291   "USER_JID","CREATED_AT","UPLOAD_TIME","SHA1_BASE32","SHA1_BASE16","HASH_SOURCE","MESSAGE_TYPE","IPV4...
  Group 1.    209-251 "FB1D928B83DEBCD2B2E53DF4C8D4C2AF99EB81E0"
  </code></pre>