gistfile1.pl

#!/usr/bin/perl

use DateTime;
use Date::Parse;

my $e1 = str2time($ARGV[0]);
my $e2 = str2time($ARGV[1]);

$d1 = DateTime->from_epoch( epoch => $e1 )->set_time_zone('floating');;
$d2 = DateTime->from_epoch( epoch => $e2 )->set_time_zone('floating');;
my $months = ($d2 - $d1)->in_units('months');

print "Months $months\n";

# ./months_apart.pl 2012-04-01 2012-05-01
# Months 0
#
# ./months_apart.pl 2012-04-01 2012-05-02
# Months 1