系統環境
#head-n1/etc/issue
RedHatEnterpriseLinuxServerrelease5.5(Tikanga)
使用redhat系統在線安裝時提示ThissystemisnotregisteredwithRHN.如下：
yuminstallgcc
Loadedplugins:rhnplugin,security
ThissystemisnotregisteredwithRHN.
RHNsupportwillbedisabled.
SettingupInstallProcess
Nopackagehttpdavailable.
Nothingtodo
解決方案：
1.卸載redhat自帶的yum組件
rpm-qa|grepyum|xargsrpm-e--nodeps
2.安裝centos的yum包
cd/etc/yum.repos.d/
32bit
wgethttp://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-3.2.22-40.el5.centos.noarch.rpm
wgethttp://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm
wgethttp://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-metadata-parser-1.1.2-4.el5.i386.rpm
64bit
wgethttp://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-metadata-parser-1.1.2-4.el5.x86_64.rpm
wgethttp://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm
wgethttp://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-3.2.22-40.el5.centos.noarch.rpm
rpm-ivh*.rpm
3.下載更新源，並存放在系統目錄中
wgethttp://docs.linuxtone.org/soft/lemp/CentOS-Base.repo
4.生成緩存並進行安裝
yummakecache
yuminstallgccgcc-c++kernel-devel