export DDL=/tmp/DB.ddl
export DB_USER=user
export DB_PASS=pass
export DB_NAME=name
export DB_HOST=localhost
> $DDL
echo "show tables;" | mysql -u $DB_USER -p$DB_PASS -h $DB_HOST $DB_NAME | grep -v "Tables_in" | while read line ; do 
   echo "=== $line ===" >> $DDL
   echo "describe $line;" | mysql -u $DB_USER -p$DB_PASS -h $DB_HOST $DB_NAME >> $DDL
done
echo "===============" >> $DDL
unset DB_USER
unset DB_PASS
unset DB_NAME
unset DB_HOST