403 Forbidden

#!/usr/bin/perl
use strict;
use warnings;
use IO::File;
use Carp;

my $user;
my @whitelist_files = ( '/etc/kill_dbwhitelist', '/etc/killwhitelist' );
if (@ARGV) {
    $user = shift;
    foreach (@whitelist_files) {
        my $whitelist_lines = IO::File->new( $_, O_RDONLY | O_CREAT );
        if ( !defined $whitelist_lines || !$whitelist_lines->opened() ) {
            carp("Error opening $_\n");
        }
        chomp( my @whitelist_lines = $whitelist_lines->getlines() );
        $whitelist_lines->close();
        my $match;
        foreach (@whitelist_lines) {
            if ( $_ =~ /^$user$/smx ) {
                $match++;
                last;
            }
        }
        unless ($match) {
            my $whitelist_lines = IO::File->new( $_, O_WRONLY | O_APPEND );
            if ( !defined $whitelist_lines || !$whitelist_lines->opened() ) {
                carp("Error opening $_\n");
            }
            $whitelist_lines->write("$user\n");
            $whitelist_lines->close();
        }
    }
}