i am looking for a way to calculate with dates.
I need something that i can say go 4 days in the past
and give me the date.
go from 02/3/1980 four days back and give me the date.
I have done experiments with 'date' but i do not know if
it is capable of doing what i want.
I thought about converting the date in
seconds since `00:00:00 1970-01-01 UTC' and then just
adding the amounts of seconds i need. But i did not found
a tool for reversion and the seconds extension is a GNU