title: AWK - request for clarification example
body: <p>I have 3 examples of using gsub:</p>
  
  <p><strong>1.</strong></p>
  
  <pre><code>echo -e "A A\nB B\nC C" | awk '{gsub($(!/B/),"",$1); print $1 "\t" $2}' 
      A
  B   B
      C
  </code></pre>
  
  <p><strong>2.</strong></p>
  
  <pre><code>$ echo -e "A A\nB B\nC C" | awk '{gsub($(!/B/),"",$2); print $1 "\t" $2}'
  A   
  B   B
  C   
  </code></pre>
  
  <p><strong>3.</strong></p>
  
  <pre><code>$ echo -e "A A\nB B\nC C" | awk '{gsub($(!/B/),"",$0); print $1 "\t" $2}'
  
  
  
  .
  </code></pre>
  
  <p>Why in the 3 example awk nothing printed? Does awk should not print?:</p>
  
  <pre><code>B   B
  </code></pre>
  
  <p>Please explain 3 examples.</p>
  
  <p>Thank you for your help.</p>