Configuration of the MySQL server遇到错误 请教

[pjx_raul]

# Configuration of the MySQL server
# Define a new MySQL root password
# Assume `mysqlrootpw' is your password
mysqladmin -h localhost -u root password mysqlrootpw

这些步骤，为什么按照以上会出现
mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: NO)'

这俩个错误分别代表什么，还请指教?刚学

另外，我也看了本论坛的其他文章 也输入了指令可以进去
pengraul@pengraul-desktop:~$ mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 18
Server version: 5.0.51a-3ubuntu5.3 (Ubuntu)

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

[cxczqfrx]

登陆mysql后，看看user表里面的host内容是否存在问题