This thread on the MySQL forum says:
By default, the OS X installation does not use a my.cnf, and MySQL just uses the default values. To set up your own my.cnf, you could just create a file straight in /etc.
OS X provides example configuration files at /usr/local/mysql/support-files/.
And if you can’t find them there, MySQLWorkbench can create them for you by:
- Opening a connection
- Selecting the ‘Options File’ under ‘INSTANCE’ in the menu.
- MySQLWorkbench will search for my.cnf and if it can’t find it, it’ll create it for you