I want to use the cal command or the date command to display the current day, then I want it to display 3 months before the current date, then add up all the days in those 3 months up to the current day. Is there a way to do this?
So today's date is displayed as:
Fri Dec 19 13:23:36 GMT 2014
3 months ago would be:
Fri Sep 19 13:23:36 GMT 2014
I want all the days added up by Linux from September 19th to December 19th, then display the result of that calculation.