[Perl] Query FTP by Net::FTP

sub query_ftp()
{
    use Net::FTP;
    
    my $ftp_host = q/ftp_host/;
    my $username = q/username/;
    my $password = q/password/;
    
    my $ftp = Net::FTP->new($ftp_host, Debug => 0) 
        or die "Cannot connect to $ftp_host: $@";
    $ftp->login($username, $password) 
        or die "Cannot login ", $ftp->message;

    my $dir = q{A/B/C};
    $ftp->cwd($dir) or die "Cannot cwd to $dir\n";
    
    my @ls = $ftp->ls();

    my $ts;
    foreach my $ls_detail ($ftp->ls('-lR')) {
        $ts = substr($ls_detail, 46, 12) if ($ls_detail =~ /$ls[-1]/);
    }
    
    printf "%20s%30s\n", $ls[-1], $ts;

    $ftp->cwd() or die "Cannot cwd to root\n";
}