title: Left outer join on two files in unix
body: <p>I need to join two files on two fields. However i should retrieve all the values in file 1 even if the join fails its like a left outer join. </p>
  
  <p>File 1:</p>
  
  <pre><code>01|a|jack|d
  02|b|ron|c
  03|d|tom|e
  </code></pre>
  
  <p>File 2:</p>
  
  <pre><code>01|a|nemesis|f
  02|b|brave|d
  04|d|gorr|h
  </code></pre>
  
  <p>output:</p>
  
  <pre><code>01|a|jack|d|nemesis|f
  02|b|ron|c|brave|d
  03|d|tom|e||
  </code></pre>