redhat系统在线安装时提示This system is not registered with RHN问题   1、卸载redhat的yum组件  www.2cto.com   [root@localhost ~]# rpm -qa | grep yum | xargs rpm -e --nodeps   2、下载centos的yum组件   [root@localhost ~]# wget  http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-metadata-parser-1.1.2-3.el5.centos.i386.rpm [root@localhost ~]# wget  http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-fastestmirror-1.1.16-16.el5.centos.noarch.rpm [root@localhost ~]# wget  http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-3.2.22-37.el5.centos.noarch.rpm   3、安装centos的yum组件 [root@localhost ~]# rpm -ivh *.rpm   4、备份/etc/yum.repos.d/下面的Redhat源 [root@localhost ~]#mv rhel-debuginfo.repo rhel-debuginfo.repo.bak [root@localhost ~]#mv rhel-source.repo rhel-source.repo.bak   5、下载更新源，并存放在系统目录中 [root@localhost ~]# wget http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo 放在目录 /etc/yum.repos.d/ 下面   6、生成缓存并进行安装 [root@localhost ~]# yum makecache