You shouldnt have to select the database table, ASSUMING the username you are using is only has access to the database you want the script to truncate. Saying that I would NOT use a master login with access to all your databases.
$somevar wil contain what mysql returned when the sql was run.
your contab woud be something like:
Code:
0 0 * * * /bin/sh /path/to/your/script >> /path/to/some/log
