Most server administrators know that the MySQL relational data base management system (RDBMS) is a highly flexible piece of software and comes with a wide range of startup options that can be used to modify its behavior. What most don’t know, however, is that the standard MySQL client comes with an equally large number of startup options, some of which are extremely useful in daily MySQL interaction. While these options are not “secret” per se, they remain largely unused, even though they can significantly ease the process of server interaction.

Source: 10 secret MySQL client startup options you should know