For those affected by the upcoming US DST change, the yest utility makes verifying the time change simple. You don't have to wait for 2:00 am, March 11th to verify your updates.
It works just like this:
$ yest +1m 3/11/2007-01:59 "%f"
Sunday, March 11th, 2007 - 03:00:00 am
Yest uses system calls to work out the new date/time so this accurately tests the system's DST update.
Obviously, if the output time is 02:00:00 am, your server won't have the correct time when DST kicks in.
The yest command line utility adds or subtracts days, hours, and/or minutes from a given date, and outputs the results in the specified format.
This utility is very useful in scripts where you must automatically determine dates and/or times such as "a week ago", "two hours ago", "tomorrow".
Yest supports most date(1) output format codes as well as a few of its own.