my %list;
my $list = "refer.dbm";
my $file = "refer.txt";

print header, start_html;

tie %list, 'SDBM_File', $list, O_CREAT | O_RDWR, 0644;
if ( !tied %list ) {
    print "database unsuccessful $!.\n";
}

my $ip       = $ENV{REMOTE_ADDR};
my $location = $ENV{HTTP_REFERER};

if ( exists $list{$location} ) {
    my $value = $list{$location};
    $value++;

    $list{$location} = $value;
}
elsif ( $list{$location} eq "" ) {
    if ( exists $list{Unknown} ) {
        my $value = $list{Unknown};
        $value++;
        $list{Unknown} = $value;
    }
    else {
        $list{Unknown} = "1";
    }
    } else {
        $list{$location} = "1";
    }