Option Files Read on Unix and Unix-Like Systems

File Name	Purpose
/etc/my.cnf	Global options
/etc/mysql/my.cnf	Global options
SYSCONFDIR/my.cnf	Global options
$MYSQL_HOME/my.cnf	Server-specific options (server only)
defaults-extra-file	The file specified with --defaults-extra-file, if any
~/.my.cnf	User-specific options
~/.mylogin.cnf	User-specific login path options (clients only)
DATADIR/mysqld-auto.cnf	System variables persisted with SET PERSIST or SE PERSIST_ONLY (server only)

Option Files Read on Windows Systems

File Name	Purpose
%WINDIR%\my.ini, %WINDIR%\my.cnf	Global options
C:\my.ini, C:\my.cnf	Global options
BASEDIR\my.ini, BASEDIR\my.cnf	Global options
defaults-extra-file	The file specified with --defaults-extra-file, if any
%APPDATA%\MySQL.mylogin.cnf	Login path options (clients only)
DATADIR\mysqld-auto.cnf	System variables persisted with SET PERSIST or SET PERSIST_ONLY (server only)

如果找到给定选项的多个实例，则最后一个实例优先

意思是后一个的配置文件会覆盖之前的配置