my $url1 = $cgi->param('url1');
my $url2 = $cgi->param('url2');

if (<DATA>) {
    while (<DATA>) {
      # blah
    }
}
else {
    open (my $fh, '>>', $0) or die "Unable to open $0: $!";
    print $fh "Data start\n$url1\n$url2\n";
    close $fh;

    exec $0
}

__DATA__