title: fflush on pipe not working in awk
body: <p>Consider the following commands:  </p>
  
  <pre><code>bash$ seq 1 3 | awk '{print $0 | "cat"; print "0"}'
  0
  0
  0
  1
  2
  3
  bash$ seq 1 3 | awk '{print $0 | "cat"; fflush("cat"); print "0"}'
  0
  0
  0
  1
  2
  3
  bash$ seq 1 3 | awk '{print $0 | "cat"; close("cat"); print "0"}'
  1
  0
  2
  0
  3
  0
  </code></pre>
  
  <p>Why does not the <code>fflush</code> command work here, whereas <code>close</code> works. That is: produces the expected output.</p>