Processs ID file $PIDFILE=/var/run/mysql/mysqld.pid

Ensuring mariadb is stopped...
Shutting down MySQL
. * 
Show there's no PID file: 
ls: cannot access /var/run/mysql/mysqld.pid: No such file or directory

Start mariadb service...
Starting MySQL
.. * 
The process id field exists, but it is not readable by an arbitrary user:
-rw-rw---- 1 mysql mysql 6 Mar 24 07:05 /var/run/mysql/mysqld.pid

Running 'service mariadb status' as root works:
 * MySQL running (17369)

But running it as other user fails:
/etc/init.d/mariadb: 375: /etc/init.d/mariadb: cannot open /var/run/mysql/mysqld.pid: Permission denied
 * MySQL is not running, but PID file exists

Manually fix the permissions...
-rw-rw-r-- 1 mysql mysql 6 Mar 24 07:05 /var/run/mysql/mysqld.pid

Can read the file, but 'service mariadb status' still fails...
 * MySQL is not running, but PID file exists

Process ID in /var/run/mysql/mysqld.pid: 17369
Try using the 'kill -0 17369' command used by the the status option:
./show_mariadb_bug: 34: kill: Operation not permitted