killall -TERM mysqld。

mysqld_safe --skip-grant-tables &

update mysql.user set authentication_string=password('123qwe') where user='root' and Host = 'localhost';

mysql> flush privileges;
mysql> quit;

killall -TERM mysqld。
mysqld_safe &

alter user 'root'@'localhost' identified by '123';

set password for 'root'@'localhost'=password('123');
cp mysql.server /etc/init.d/mysql
chmod +x /etc/init.d/mysql
chkconfig --add mysql