[me ~]$ perl datefail.pl --startday='-15 days' --endday='-14 days'
Start with Today
20151120T22:51-0700
Fix timezone
20151120T21:51-0800
Set the right day
20151105T21:51-0800
Strip the hours
20151105T00:51-0800
Strip the minutes
20151105T00:00-0800
[me ~]$ perl datefail.pl --startday='-19 days' --endday='-18 days'
Start with Today
20151120T22:51-0700
Fix timezone
20151120T21:51-0800
Set the right day
20151101T21:51-0800
Strip the hours
20151101T01:51-0700
Strip the minutes
20151101T01:00-0700