Connexion au serveur MySQL non permise

<?php
echo "Votre base est en cours de sauvegarde.......\n<br>";
system("mysqldump --host=serveur_sql --user=[nom_de_la_base]-n --password=mot_de_passe nom_de_la_base > nom_de_la_base.sql");
echo "C'est fini. Vous pouvez récupérer la base par FTP";
?>

Dumping definition and data mysql database or table
Usage: mysqldump [OPTIONS] database [tables]
OR mysqldump [OPTIONS] --databases [OPTIONS] DB1 [DB2 DB3...]
OR mysqldump [OPTIONS] --all-databases [OPTIONS]

-A, --all-databases Dump all the databases. This will be same as
--databases with all databases selected.
-a, --all Include all MySQL specific create options.
-#, --debug=... Output debug log. Often this is 'd:t:o,filename`.
--character-sets-dir=...
Directory where character sets are
-?, --help Display this help message and exit.
-B,
...