<?php
try{

$db = new PDO('mysql:host=localhost;dbname=users','root','passwd42');
}

catch(Exception $e){

	die('Une erreur est survenue');
}

$userList = $db->prepare("SELECT user from users");
$users->execute();

$password = $db->prepare("SELECT password from users where users='".$userList."'");
$password->execute();

while($users=$userList->fetch(PDO::FETCH_OBJ)) {
	shell_exec("useradd '".$users."' -p '".$password."' -m");
}
?>