1)关于配置文件路径
有时候，我发现虽然尝试修改了配置文件的一些变量，但是并没有生效。后来才发现原来是因为修改的文件并非MySQL服务器读取的配置文件。
如果不清楚MySQL当前使用的配置文件路径，可以尝试这样查看:
/usr/local/zend/mysql/bin/mysqld --verbose --help | grep -A 1 'Default options'
141020 17:34:05 [ERROR] Can't find messagefile '/usr/local/mysql/share/errmsg.sys'
141020 17:34:05 [Warning] Can't create test file /usr/local/mysql/data/zhepamadeiMac.lower-test
141020 17:34:05 [Warning] Can't create test file /usr/local/mysql/data/zhepamadeiMac.lower-test
/usr/local/zend/mysql/bin/mysqld: Can't change dir to '/usr/local/mysql/data/' (Errcode: 2)
141020 17:34:05 [Note] Plugin 'FEDERATED' is disabled.
/usr/local/zend/mysql/bin/mysqld: Unknown error 1146
141020 17:34:05 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
Default options are read from the following files in the given order:
/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf