mariadb/debian/mysql-common.README.Debian.in

[passwords]
If you change the password of the root user (which is strongly recommended)
you have to create a personal mysql config file in order to let cron run
the /etc/cron.daily script without asking you for the password.
The /root/.my.cnf file should be chmod 0600 (-rw------- root root .my.cnf)
and have the following content:
[mysqladmin]
user            = root
password        = <secret>

[more than one process]
Note that the shutdown script cannot use the pid number stored in
/var/run, since it is for the first mysqld thread, but we need to kill
the most recent thread to shutdown the server. The upstream developers
are aware of this bug. When maintaining your database, you should use
mysqladmin with your password to shutdown and reload the server rather
than /etc/init.d/mysql.

Scott Hanson               and          Christian Hammers
<shanson@debian.org>                    <ch@debian.org>