Yum install mysql prompts "This system is not registered with RHN" problem. The Red Hat shows This system is not registered with RHN because RHN is not registered in the red hat. Work:( und: (assuming you have installed yum and the network is smooth) change the yum source, that is, change the/etc/yum. repos. d/rhel-debuginfo.repo file. Enter/etc/yum. repos. d/directory. Enter wget http://docs.linuxtone.org/soft/lemp/centos-base.repoin in the terminal to go to centos-Base. repo file, which is the source file of centos, you just need to rename it as a rhel-debuginfo.repo, a backup of the previous file. Installation steps: www.2cto.com yum install mysqlyum install mysql-serveryum install mysql-develchgrp-R mysql/var/lib/mysqlchmod-R 770/var/lib/mysqlservice mysqld start mysqlSET password for 'root '@' localhost' = PASSWORD ('secret _ password '); // set the password