Check if a variable is integer
==============================

Public domain
********************************************************************************

    #!/bin/bash
    VAR="2000"
    if [ $(echo "$VAR" | grep -E "^[0-9]+$") ]; then
      echo $VAR IS a valid integer.
    else
      echo $VAR is NOT a valid integer.
    fi
********************************************************************************
_BY: Pejman Moghadam_  
_TAG: bash-script, bash_  
_DATE: 2011-08-23 15:00:25_