场景
想要安装python3，于是乎将linux自带的python卸载了
接着发现yum命令就不能用了
解决
下面是删除python和查看是否删除干净的命令
rpm -qa|grep python|xargs rpm -ev --allmatches --nodeps
查看是否删干净了
whereis python|xargs rm -frv
没有删干净的话将其删除干净
再继续下一步
我的系统是7.6的，你只需要在centos下找到对应你系统文件夹下的软件即可
或者执行下面语句进行下载，使用wge或者wget
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-backports-1.0-8.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-2.7.5-76.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/libxml2-python-2.9.1-6.el7_2.3.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-backports-ssl_match_hostname-3.5.0.1-1.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-chardet-2.2.1-1.el7_1.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-devel-2.7.5-76.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-iniparse-0.4-9.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-ipaddress-1.0.16-2.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-kitchen-1.1.1-5.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-libs-2.7.5-76.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-pycurl-7.19.0-19.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-setuptools-0.9.8-7.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-urlgrabber-3.10-9.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/python-virtualenv-15.1.0-2.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/rpm-4.11.3-35.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/rpm-build-4.11.3-35.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/rpm-build-libs-4.11.3-35.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/rpm-libs-4.11.3-35.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/rpm-python-4.11.3-35.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/rpm-sign-4.11.3-35.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/yum-3.4.3-161.el7.centos.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/yum-plugin-aliases-1.1.31-50.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-50.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/yum-plugin-protectbase-1.1.31-50.el7.noarch.rpm
wge http://vault.centos.org/7.6.1810/os/x86_64/Packages/yum-utils-1.1.31-50.el7.noarch.rpm
等待上面语句执行难完毕，所需的软件下完成后，
再执行如下语句，进行安装即可
rpm -ivh --replacepkgs *.rpm --nodeps --force
yum makecache
到这里就已经修复完成了