How to get a day before current time in Bash

In Bash, use the -d option to display yesterday’s date or an earlier date, as shown below. Display yesterday’s date

[tum@ezylinux ~]$ date -d yesterday
Wed Mar 12 14:53:56 ICT 2014

or

[tum@ezylinux ~]$ date -d "1 day ago"
Wed Mar 12 14:53:56 ICT 2014

Display the date three days ago

[tum@ezylinux ~]$ date -d "3 day ago"
Mon Mar 10 14:56:34 ICT 2014

[tum@ezylinux ~]$ date +%Y-%m-%d -d "3 day ago"
2014-03-10