Command to use in order to see the default values for a mysql/mariadb server.
On RHEL and RHEL-inspired distributions, right up to Fedora 19:
/usr/libexec/mysqld --verbose --help
It’s all pretty much listed there for you. Very helpful for deciding what to clutter your /etc/my.cnf with and as a sanity check against suggestions found in various places on the web.
Do this and you’ve got yourself a quick-reference guide:
/usr/libexec/mysqld --verbose --help >mysql-manual.txt