title: Integer addition in shell
body: <p>Here is my simple shell code. I want the result to be 2.Shell treats everything as a string.
  How can i get this done ?</p>
  
  <pre><code>num=1
  num=$(( $num + 1 ))
  </code></pre>
  
  <p>EDIT :</p>
  
  <p>Complete code : Whats wrong in this if i want to print from 1 to 10 ?</p>
  
  <pre><code>#! /bin/bash
  
  num=1
  until test $num -eq 10
  do
      num=$(( $num + 1 ))
      echo $num
  done
  </code></pre>