mysql_secure_installation

le minimum syndical.

Switch to unix_socket authentication [Y/n] n
Remove anonymous users? [Y/n] y
Disallow root login remotely? [Y/n] y
Remove test database and access to it? [Y/n] y
Reload privilege tables now? [Y/n] y

SHOW {DATABASES | SCHEMAS}
    [LIKE 'pattern' | WHERE expr]

SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| test               |
+--------------------+

SHOW DATABASES LIKE 'm%';
+---------------+
| Database (m%) |
+---------------+
| mysql         |
+---------------+