title: how to get unique values set from a repeating values list
body: <p>I need to parse a large log file (flat file), which contains  two column of values (column-A , column-B). </p>
  
  <p>Values in both columns are repeating. I need to find for each unique value in column-A , I need to find a set of column-B values. </p>
  
  <p>Is this can be done using unix shell command or need to write any perl or python script? What are the ways this can be done?</p>
  
  <h2>Example:</h2>
  
  <pre><code>xxxA 2
  xxxA 1
  xxxB 2
  XXXC 3
  XXXA 3
  xxxD 4
  </code></pre>
  
  <h2>output:</h2>
  
  <pre><code>xxxA - 2,1,3
  xxxB - 2
  xxxC - 3
  xxxD - 4
  </code></pre>