环境：CentOS7下MySQL5.7
启动 systemctl start mysqld
停止 systemctl stop mysqld
查看 ps -ef | grep mysql
修改密码执行这一条命令即可
set password for root@localhost = password('fSmJ3y$2Bd!83H2@H');
mysql -uroot -pfSmJ3y$2Bd!83H2@H
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'fSmJ3y$2Bd!83H2@H' WITH GRANT OPTION;