Recently i encounter an uprising among PHP Developers that , they must write a script additionally checking the strength of MySQL user password at creation time.
So, just for note that there is ready to use plugin in MySQL named: validate_password.so

The file location is default in plugin_dir in Linux:

mysql> select @@plugin_dir;
+--------------------------+
| @@plugin_dir             |
+--------------------------+
| /usr/lib64/mysql/plugin/ |
+--------------------------+
1 row in set (0,00 sec)

List this directory:

[root@linuxsrv3 plugin]# ls
adt_null.so     auth_test_plugin.so  innodb_engine.so      mypluglib.so          qa_auth_server.so   validate_password.so
auth.so         daemon_example.ini   libdaemon_example.so  qa_auth_client.so     semisync_master.so
auth_socket.so  debug                libmemcached.so       qa_auth_interface.so  semisync_slave.so

As you see there is a …