Shell Programming and Scripting

I want to create shell script check input startdate befor enddate.

Code :

echo "Enter StartDate (ddMM20YY) :"
read startdate
echo "Enter EndDate (ddMM20YY) :"
read enddate
Sdd=`expr substr "$startdate" 1 2`
Smm=`expr substr "$startdate" 3 2`
Syyyy=`expr substr "$startdate" 5 4`
echo "$Sdd $Smm $Syyyy"

echo "Enter EndDate (ddMM20YY) :"
read enddate
Edd=`expr substr "$enddate" 1 2`
Emm=`expr substr "$enddate" 3 2`
Eyyyy=`expr substr "$enddate" 5 4`
echo "$Edd $Emm $Eyyyy"

....
......

#expect output#

#Enter StartDate (ddMM20YY) :
#20052009
#Enter EndDate (ddMM20YY) :
#11052009

#Incorectly,Please Try again.


(How to check about startdate before enddate )
Help suggestion please.. Thank You

if it is possible to use the date in YYYYMMDD format then you can just do a simple numerical comparison.

alternatively, you can also convert the dates in YYYYMMDD form just for comparison inside your script.

there might be other ways also.