title: how do I count numbers from command line?
body: <pre><code>1
  1
  1
  2
  2
  2
  3
  3
  </code></pre>
  
  <p>Let's say I have a file contains these numbers, I want to count those numbers like this</p>
  
  <p>(num):(occurence)</p>
  
  <pre><code>1:3
  2:3
  3:2
  </code></pre>
  
  <p>How do I do this in shell script?</p>