#!/usr/bin/perl

use strict;
use warnings 'all';

use Date::Manip;

my $month = UnixDate ParseDate ("today"), "%B %Y";
my $date  = ParseDate "3rd tuesday in $month";
if ($date lt ParseDate ("now")) {
    my $month = UnixDate ParseDate ("next month"), "%B %Y";
       $date  = ParseDate "3rd tuesday in $month";
}
print UnixDate $date => "%F\n";
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The documentation of the module comes with lots of examples (not only the ones in the Examples section). The routines are discussed into detail in the Routines section, taking most of the 41 page documentation....

Abigail