In a code as an example below, you can only download the contents of the $ arr variable, without having to write the contents in any folder.
<!doctype html>
<html>
<head>
<meta charset="iso-8859-2">
<title>Untitled Document</title>
</head>
<body>
<? //Generate text file on the fly
header("Content-type: text/plain");
header("Content-Disposition: attachment; filename=savethis.txt");
for($i=0;$i<100;$i++){
$arr[] = "teste ".$i;
}
print "Texto de teste...\n";
print_r($arr);
?>
</body>
</html>
Thank you Marco