切换到root用户，然后进入mysql 的bin目录后，
root@cps-desktop:/usr/local/mysql/bin# /etc/init.d/mysql stop
root@cps-desktop:/usr/local/mysql/bin# ./mysqld_safe --user=mysql --skip-grant-tables --skip-networking&
root@cps-desktop:/usr/local/mysql/bin# ./mysql -u root mysql
mysql> UPDATE user SET Password=PASSWORD('newpassword') where USER='root';
mysql> FLUSH PRIVILEGES;
mysql> quit;
最后重启数据库：
root@cps-desktop:/usr/local/mysql/bin# /etc/init.d/mysql restart
root@cps-desktop:/usr/local/mysql/bin# mysql -u root -p
Enter password: <输入新设的密码newpassword>
这里要注意，mysql的bin目录会不一样，我的是在/usr/bin#