# date
Sun Sep 11 07:59:16 IST 2012
NEW_expration_DATE = Sun Sep 21 07:59:16 IST 2012
date
Sun Sep 23 08:19:56 BST 2012
NEW_expration_DATE=$(date -d "+10 days")
echo $NEW_expration_DATE
Wed Oct 3 08:12:33 BST 2012
date -d "Sun Sep 11 07:59:16 IST 2012+10 days"
Fri Sep 21 03:29:16 BST 2012