title: Linux shell script Date arithmetic
body: <p>I have a shell script </p>
  
  <pre><code> #!/bin/bash
  START=$(date +%s)
  echo "  Start| $START "
  # do something
  # start your script work here
  #  
  # your logic ends here
  END=$(date +%s)
  echo "  End|  $END "
  DIFF=$(( $END-$START ))
  echo "  Diff in seconds|"  $DIFF
  </code></pre>
  
  <p>Still getting this error
    Start| 1349769151
    End|  1349769151
   ")49769151rror: invalid arithmetic operator (error token is "</p>
  
  <p>I know it is basic, so I have been searched and debug for two days already.
  But still gets nothing works on this.
  Plz help!</p>