Validate date format in a shell script

Question

I have to create a Shell Script wherein one of the parameters will be the date in the format dd/mm/yyyy. My question is, how can I check if the Date passed as parameter real

Answer 1

Use date

date "+%d/%m/%Y" -d "09/99/2013" > /dev/null  2>&1
 is_valid=$?

If you do not get 0 then date is in invalid format.