網上看到有同學yum不能使用的消息，出現了下面的結果
無賴的使用了網上的很多方法，還是不行。
於是我卸載了python和yum，覺得自己重新安裝python和yum。
步驟1：卸載python
rpm -qa|grep python|xargs rpm -e --allmatches --nodeps whereis python|xargs rm -fr
步驟2：卸載yum
rpm -qa|grep yum|xargs rpm -e --allmatches --nodeps rm -rf /etc/yum.repos.d/* whereis yum|xargs rm -fr
步驟3：安裝python
在任何一個鏡像站中找到你系統對應版本的python rpm包（我的是centos 6.9的64位系統，使用的鏡像是http://mirrors.163.com/centos/6.9/os/x86_64/Packages/）
mkdir /usr/local/src/python wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/python-2.6.6-66.el6_8.x86_64.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/python-iniparse-0.3.1-2.1.el6.noarch.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/python-pycurl-7.19.0-9.el6.x86_64.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/python-devel-2.6.6-66.el6_8.x86_64.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/python-libs-2.6.6-66.el6_8.x86_64.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/python-urlgrabber-3.9.1-11.el6.noarch.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/rpm-python-4.8.0-55.el6.x86_64.rpm
切換到/usr/local/src/python路徑下
rpm -ivh python-* rpm-python-*
如果中間過程出現了類似下面的代碼，這是包與包之間的依賴關系，只需要卸載已經安裝的包（rpm -e 包名（沒有.rpm后綴）），然后先安裝依賴包
如：
rpm -e yum-metadata-parser-1.1.2-16.el6.x86_64 rpm -ivh /yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
步驟4：安裝yum
mkdir /usr/local/src/yum wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/yum-3.2.29-81.el6.centos.noarch.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/yum-metadata-parser-1.1.2-16.el6.x86_64.rpm wget http://mirrors.163.com/centos/6.9/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.30-40.el6.noarch.rpm
切換到/usr/local/src/python路徑下
rpm -ivh yum-*
步驟5：測試
運行
yum
（成功）
