redhat默认自带的yum源需要注册，才能更新，报错：

This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.

可替换为centos对应的源。 操作如下：

1、删除redhat原有的yum

rpm -aq|grep yum|xargs rpm -e –nodeps

2、下载yum安装文件

wget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-3.2.29-81.el6.centos.noarch.rpm
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.30-40.el6.noarch.rpm
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/python-iniparse-0.3.1-2.1.el6.noarch.rpm

3、安装组件

rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm
rpm -ivh yum-metadata-parser-1.1.2-16.el6.x86_64.rpm

下面安装失败了

# rpm -ivh yum-3.2.29-81.el6.centos.noarch.rpm yum-plugin-fastestmirror-1.1.30-37.el6.noarch.rpm
warning: yum-3.2.29-81.el6.centos.noarch.rpm:Header V3 RSA/SHA1Signature, key ID c105b9de: NOKEY
error: Failed dependencies:
python-urlgrabber >= 3.9.1-10 is needed byyum-3.2.29-81.el6.centos.noarch

少python-urlgrabber 组件，下载：

http://mirrors.163.com/centos/6/os/x86_64/Packages/python-urlgrabber-3.9.1-11.el6.noarch.rpm


# rpm -Uvh python-urlgrabber-3.9.1-11.el6.noarch.rpm
warning:python-urlgrabber-3.9.1-11.el6.noarch.rpm: Header V3 RSA/SHA1 Signature, key IDc105b9de: NOKEY
Preparing... ########################################### [100%]
file /usr/lib/python2.6/site-packages/urlgrabber/grabber.py from installof python-urlgrabber-3.9.1-11.el6.noarch conflicts with file from packagepython-urlgrabber-3.9.1-9.el6.noarch
file /usr/lib/python2.6/site-packages/urlgrabber/grabber.pyc frominstall of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file frompackage python-urlgrabber-3.9.1-9.el6.noarch
file /usr/lib/python2.6/site-packages/urlgrabber/grabber.pyo frominstall of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file frompackage python-urlgrabber-3.9.1-9.el6.noarch
file /usr/lib/python2.6/site-packages/urlgrabber/progress.pyc frominstall of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file frompackage python-urlgrabber-3.9.1-9.el6.noarch
file /usr/lib/python2.6/site-packages/urlgrabber/progress.pyo frominstall of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file frompackage python-urlgrabber-3.9.1-9.el6.noarch

安装源

http://mirrors.163.com/.help/CentOS7-Base-163.repo

把文件里面的$releasever全部替换为版本号：6