Shell Programming and Scripting

I'm not sure exactly how to display the day of the week when a particular date is entered. For example, if April 12 2016 is entered then the result should be Tuesday. Or if June 17 2015 is entered then the result should be Wednesday. I know you can use

Code:

$ date -d "1974-01-04" +"%A"

but I want to be able to type in any date in the terminal, and not have the date in my script. Also, what about finding all the years in which a specific date falls on for the same day of the week as that given day? Like April 5 1996 and April 5 2002 both fall on a Friday, I want to be able to calculate that as well in a separate script.

Depending on your OS, date behaves differently. GNU date, for instance, accepts many datetime formats; just try it out. It will work out of the box with your above mentioned date. FreeBSD's date needs a format string:

Code:

date -jf"%B %d %Y" "April 12 2016"
Tue Apr 12 18:04:59 CEST 2016

You'll need to make sure there's no ambiguities like in numerical day/month representations.