Ho trovato questa funzione su php.net che sembrerebbe fare al caso mio:

function recur_mkdirs($path, $mode = 0777) //creates directory tree recursively
{
//$GLOBALS["dirseparator"]
$dirs = explode($GLOBALS["dirseparator"],$path);
$pos = strrpos($path, ".");
if ($pos === false) { // note: three equal signs
// not found, means path ends in a dir not file
$subamount=0;
}
else {
$subamount=1;
}

for ($c=0;$c < count($dirs) - $subamount; $c++) {
$thispath="";
for ($cc=0; $cc <= $c; $cc++) {
$thispath.=$dirs[$cc].$GLOBALS["dirseparator"];
}
if (!file_exists($thispath)) {
//print "$thispath
";
mkdir($thispath,$mode);
}


}

}

recur_mkdirs($new_url);


Mi genera questo errore:

Notice: Undefined index: dirseparator
Warning: explode(): Empty delimiter.

cosa vuol dire??

cos'e' la variabile globale: $GLOBALS["dirseparator"] ??