[root@luozhonghua ~]# /usr/bin/mysqladmin -u root password 'aaaaaa'
/usr/bin/mysqladmin: connect to server at 'localhost' failed
error: 'can't connect to local mysql server through socket '/var/lib/mysql/mysql.sock' (2)'
check that mysqld is running and that the socket: '/var/lib/mysql/mysql.sock' exists!
解决：
1》/etc/rc.d/init.d/mysqld status 看看mysql是否已经启动
2》service mysqld start