subtract days from a date in bash

Question

I want to subtract \"number of days\" from a date in bash. I am trying something like this ..

echo $dataset_date #output is 2013-08-07

echo $date_diff #outp         


        

Answer 1

You are specifying the date incorrectly. Instead, say:

date --date="${dataset_date} -${date_diff} day" +%Y-%m-%d

If you need to store it in a variable, use $(...):

p_dataset_date=$(date --date="${dataset_date} -${date_diff} day" +%Y-%m-%d)