閒來無事，一不小心，卸載了python，發現yum也就掛了。
乾脆一不做二不休，把他們都卸載乾淨，重頭裝過，可是死活沒法裝成功。
一直卡着我的奔潰問題如下：
[root@izuf6eu0p527rbj9f5lqnhz tmp]# yum
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
/usr/lib64/python2.7/site-packages/rpm/_rpm.so: undefined symbol: rpmpkgVerifySigs
Please install a package which provides this module, or
verify that the module is installed correctly.
It's possible that the above module doesn't match the
current version of Python, which is:
2.7.5 (default, Apr 2 2020, 13:16:51)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)]
If you cannot solve this problem yourself, please go to
the yum faq at:
http://yum.baseurl.org/wiki/Faq
折騰半天，google、百度大半天，都沒成功解決，最後看到一篇博客提到是rpm包沒有全部下載完的問題。然後，反反覆覆多次嘗試，終於，最後一次被我折騰成功了，那個累啊。
這兒記錄下，重裝yum和python，需要下載的rpm包和一些操作步驟，下次少踩點坑。
rpm常用參數
-i: --install，安裝包
-U: --update，更新包
-e: --erase，刪除包
卸載python
rpm -qa| grep python| xargs rpm -ev --allmatches --nodeps
whereis python |xargs rm -frv
卸載yum
rpm -qa|grep yum|xargs rpm -ev --allmatches --nodeps
whereis yum |xargs rm -frv
下載rpm包
我這裏通過163的鏡像倉庫下載，注意需要根據自己的系統大版本號去下載對應的rpm包。倉庫地址
查看系統版本可以用下面的命令
[root@izuf6eu0p527rbj9f5lqnhz tmp]# cat /etc/redhat-release
CentOS Linux release 7.3.1611 (Core)
wget http://mirrors.ustc.edu.cn/centos/7/os/x86_64/Packages/libxml2-python-2.9.1-6.el7_2.3.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/libxml2-python-2.9.1-6.el7.4.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-4.11.3-43.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-build-4.11.3-43.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-build-libs-4.11.3-43.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-libs-4.11.3-43.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-sign-4.11.3-43.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-python-4.11.3-43.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-2.7.5-88.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/dbus-python-devel-1.1.1-9.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-libs-2.7.5-88.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-pycurl-7.19.0-19.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-setuptools-0.9.8-7.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-urlgrabber-3.10-10.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-iniparse-0.4-9.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-backports-1.0-8.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-backports-ssl_match_hostname-3.5.0.1-1.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-chardet-2.2.1-3.el7.noarch.r
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-ipaddress-1.0.16-2.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-kitchen-1.1.1-5.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/python-virtualenv-15.1.0-2.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-167.el7.centos.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-utils-1.1.31-53.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-53.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-protectbase-1.1.31-53.el7.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-aliases-1.1.31-53.el7.noarch.rpm
安裝更新rpm包
rpm -Uvh --force --nodeps --replacepkgs *.rpm
檢查
輸入python和yum命令進行測試，沒有異常，安裝完成。
