title: what does it means in awk script? `awk -F "|" '{!a[$1]++}{printf RS $1}{print FS $2}' input.txt`
body: <p>I need meaning of below code in unix, and help me go forward..</p>
  
  <pre><code>`awk -F "|" '{!a[$1]++}{printf RS $1}{print FS $2}' input.txt`
  </code></pre>
  
  <p>My sample i/p file is like below </p>
  
  <pre><code>1|Balaji 1|Kumar 3|India 3|China 3|Australia 1|Dinesh
  </code></pre>
  
  <p>I need o/p like below </p>
  
  <pre><code>1|Balaji|Kumar|Dinesh 3|India|China|Australia
  </code></pre>