[root@www.woai.it ~]# service mysql stop

[root@www.woai.it ~]# mysqld_safe --skip-grant-tables &

[root@www.woai.it ~]# mysqld_safe --skip-grant-tables --skip-networking &

[root@www.woai.it ~]# mysql -p

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

mysql> flush privileges;
mysql> quit;

[root@localhost ~]# service mysql restart

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

mysql> set password for 'root'@'localhost'=password('123');

[root@bright ~]# cat /root/.mysql_secret
# Password set for user 'root@localhost' at 2015-03-27 23:12:10
:Jj+FTiqvyrF
[root@bright ~]# cd /usr/local/mysql/bin/
[root@bright bin]# ./mysqladmin -u root -h localhost password '123456' -p

mysqladmin: [Warning] Using a password on the command line interface can be insecure.
Warning: Since password will be sent to server in plain text, use ssl connection to ensure password safety.

shell>mysql -uroot -p'password' #password即.mysql_secret里的密码
mysql>SET PASSWORD = PASSWORD('newpasswd');

shell>service mysqld stop #停止mysql服务
shell>mysqld_safe --skip-grant-tables & #以不启用grant-tables模式启动mysql
shell>mysql -uroot -p #输入命令回车进入，出现输入密码提示直接回车。
mysql>use mysql;
mysql>update user set password=PASSWORD("123456")where user="root"; #更改密码为 newpassord
mysql>flush privileges; #更新权限
mysql>quit #退出

shell>service mysqld stop #停止mysql服务
shell>mysqld_safe --skip-grant-tables & #以不启用grant-tables模式启动mysql
shell>mysql -uroot -p #输入命令回车进入，出现输入密码提示直接回车。
mysql > set password for root@localhost = password('mysqlroot');

shell>/path/mysqladmin -u UserName -h Host password 'new_password' -p