title: counting duplicates in a sorted sequence using command line tools
body: <p>I have a command (cmd1) that greps through a log file to filter out a set of numbers. The numbers are 
  in random order, so I use sort -gr to get a reverse sorted list of numbers. There may be duplicates within 
  this sorted list. I need to find the count for each unique number in that list. </p>
  
  <p>For e.g. if the output of cmd1 is:</p>
  
  <pre><code>100 
  100 
  100 
  99 
  99 
  26 
  25 
  24 
  24
  </code></pre>
  
  <p>I need another command that I can pipe the above output to, so that, I get:</p>
  
  <pre><code>100     3
  99      2
  26      1
  25      1
  24      2
  </code></pre>