[mysql] 适用于mysql命令行客户端-

[mysql] applies to the mysql command line client - [mysql and client options]

[客户端] 适用于所有连接的客户端(包括mysql cli)-

[client] applies to all connecting clients (including mysql cli) - [mysql and client options]

[mysqld] 适用于mysql服务器- [服务器选项]

[mysqld] applies to the mysql server - [server options]

[mysqldump] 适用于同名的实用程序- [mysqldump选项]

[mysqldump] applies to the utility of the same name - [mysqldump options]

...等

(-)和(_)之间的区别在于使用它的上下文.

The difference between the (-) and the (_) is the context in which it is used.

(-)用于命令行参数，(_)用于选项文件参数.

(-) is used in command line parameters, where (_) is used in options file parameters.

您可以在文档中看到更多信息: http://dev.mysql.com/doc/refman/5.5/en/option- files.html

You can see more in the docs: http://dev.mysql.com/doc/refman/5.5/en/option-files.html