i yedekleme benim tam MySQL veritabanı için bu komutu kullanıyorum ..

$backupFile = $dbname . date("Y-m-d-H-i-s") . '.sql';
$command = "mysqldump -h$hostname -u$username -p$password $dbname > $backupFile";
system($command);

I am getting blank file. And i am using XAMMP on windows. I have already used exec() but also getting blank file. And but on shell it has successfully done. Whats wrong in this code.