title: awk - if column = null
body: <p>Using awk, how would you assign 'null' a value to read?</p>
  
  <p>I'm sure there's a set character for this, I just can't find it.</p>
  
  <p>For example,</p>
  
  <p>I've got a string of awk like this:</p>
  
  <pre><code>awk '
  $3==24{print "stuff"}
  $3==23{print "stuff"}
  '
  </code></pre>
  
  <p>I need to know how to account for blank colums using the same format so that if $3 = blank {print "stuff"}</p>
  
  <p>Thanks!</p>