title: How can we use UpdateAttribute processor for assigning variable of FlowFile content in Apache Nifi
body: <p>I need some help in UpdateAttribute processor:
  I have a CSV file which contains hostnames. I need to separate each hostname in the FlowFile and pass it as a variable to the REST API.<br />
  My REST API part is working fine when passing data manually. However, I didn't get how to pass a variable value as hostname in it.</p>
  <p>Sharing sample file:</p>
  <pre><code>SRHAPP001,SRHWEBAPP002,SRHDB006,SRHUATAPP4,ARHUATDB98
  </code></pre>