module for manipulating dates

 Date::Manip is a Perl module that contains a set of routines designed to make
 any common date/time manipulation easy to do. It aims to make operations like
 comparing two times, calculating a time a given amount of time from another,
 or parsing international times simpler.
 .
 The focus of Date::Manip has been to be able to do ANY desired date or time
 operation easily, though not necessarily quickly. There are other modules
 that can do a small subset of these operations quicker, so if speed is a
 primary issue, you should look elsewhere.