Shell Programming and Scripting

#!/usr/bin/bash
clear
export NLS_LANG=AMERICAN_AMERICA.AL32UTF8



if [ $# -lt 2 ]  ; then
        echo " Incorrect Number of Arguments";
        echo " Usage : Main_Script <FROM_DATE> <TO_DATE>";
        echo " Example : Main_Script 21-JUL-2015 30-JUL-2015";
        exit;

fi;

if [ $# == 2 ]; then
      if [[ $1 == [0-3][0-9]-[A-Z][A-Z][A-Z]-[0-9][0-9][0-9][0-9] ]]; then
              if  [[ $2 == [0-3][0-9]-[A-Z][A-Z][A-Z]-[0-9][0-9][0-9][0-9] ]];
                  then
                  d1=`date -d $1 +%s`
                  d2=`date -d $2 +%s`
                echo $d1;
                echo $d2;

                                        if [[ $d2 -gt $d1 ]];
                                        then
                                        echo "correct";

                      else
                                                 echo "Start date is more than end date";

                         exit;

 fi;
                   else
                   echo "Incorrect date format";
                   echo  $2;
                                  echo "Usage : DD-MMM-YYYY";
                  echo " Example :  Main_Script 21-JUL-2015 30-JUL-2015";
                  exit;
       fi;
           else
            echo "Incorrect date format";
                echo  $1;
                 echo "Usage : DD-MMM-YYYY";
                echo " Example :  Main_Script 21-JUL-2015 30-JUL-2015";
                exit;


    fi;
fi;