sub two_pass {
    my @matched;
    open (my $FH, "<$file");
    while (my $rec = <$FH>) {
        if ( $rec =~ '500_000' ) {
                push @matched, $rec;
        }
        if ( $rec =~ '500_001' ) {
                push @matched, $rec;
        }
    }
    print "two pass: " . @matched;
    close $FH;
}