mysql系列一：查看mysql服务配置文件的位置
which mysqld
/usr/sbin/mysqld --verbose --help | grep -A 1 'Default options'
Default options are read from the following files in the given order:
/etc/my.cnf /etc/mysql/my.cnf /usr/etc/my.cnf ~/.my.cnf
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默认配置选项会按一下文件的顺序读取：
/etc/my.cnf
/etc/mysql/my.cnf
/usr/etc/my.cnf
~/.my.cnf