title: Filter out rows from column A based on values in column B
body: <p>I have a CSV file that contains two columns. First column is a list of all subscribers and second column is a list of subscribers who need to be excluded from a mailing:</p>
  <pre><code>all,exclusions
  alice@example.com,charles@example.com
  bill@example.com,alice@example.com
  charles@example.com
  daisy@example.com
  esther@example.com
  </code></pre>
  <p>I need to end up with an output of all subscribers from first column who are not listed in the second column. The desired output is something like this:</p>
  <pre><code>bill@example.com
  daisy@example.com
  esther@example.com
  </code></pre>
  <p>So far all I have is this:</p>
  <p><code>awk -F, '(NR&gt;1) {if($1!=$2) {print}}' subs.csv</code></p>
  <p>This of course will only filter out the rows when there are matching values in both columns on the same row.
  Thanks for any help.</p>