#!usr/bin/perl
use say;
use strict;
use warnings;
use DateTime;

my $time_now = DateTime
    ->now( time_zone => 'local' );

say $time_now->strftime("%Y, %m, %d");

my $one_month_ago = DateTime
    ->now( time_zone => 'local' )
    ->subtract( days => 30 );

say $one_month_ago->strftime("%Y, %m, %d");

__END__

$ perl test.pl
2017, 06, 23
2017, 05, 24