Centos7.8误删Python2.7之后，导致yum和Python命令无法使用
本文主要给出了Centos7.8安装Python3以及误删Python2.7之后导致yum和Python命令无法使用的解决办法.
Centos7.8误删Python2.7之后，导致yum和Python命令无法使用
先简单介绍下我的情况与背景:
我在昨天写一个模块，跑Python脚本报错，由于我不熟习Python2，3之间语法有差异，导致脚本一直跑步起来，后面安装了Python3， 由于我个人安装了软件新版本一般会卸载旧版本以节约空间，而yum模块采用Python2编写，导致使用yum命令会一直报错:
需要提前说明的是，如果你只是安装了Python3并没有删除Python2的话，那只需要去yum配置文件里将默认编译器指向Python2即可，后面也会给出解决方案。
情况一报错日志
若安装了Python3且没有删除Python2，那么启动yum命令会报错:
File "/usr/bin/yum", line 30
except KeyboardInterrupt, e:
^
SyntaxError: invalid syntax
情况一报错原因
这种情况的原因是yum配置文件解释器默认是/usr/bin/python，而安装Python3之后教程里一般会将这个软连接指向Python3所在的目录，也就是程序引用了错误的Python版本解释器，解决办法就将yum配置文件解释器指向原来的Python2版本:
# 需要改 /usr/bin/yum 和 /usr/libexec/urlgrabber-ext-down ,改法一样,这儿以第一个为例
vim /usr/bin/yum
#!/usr/bin/python # 修改之前
import sys
try:
import yum
except ImportError:
print >> sys.stderr, """\
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
#!/usr/bin/python2.7 # 修改之后
import sys
try:
import yum
except ImportError:
print >> sys.stderr, """\
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
当然如果你之前的Python2版本不是2.7那可以通过 whereis python查看
[root@node02 local]# whereis python
python: /usr/bin/python /usr/bin/python2.7 /usr/lib/python2.7 /usr/lib64/python2.7 /etc/python /usr/include/python2.7 /usr/share/man/man1/python.1.gz
如果你是像我一样更复杂的场景，也就是将Python2误删了，那处理起来相对来说麻烦一些
情况二报错日志
我删除Python2之后重新安装了Python2，并且根据另一个虚拟机节点建立了软连接，这次启动yum不报错，但是出现下面的信息提示:
$ yum install
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
No module named yum
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, Dec 25 2022, 22:37:27)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-44)]
If you cannot solve this problem yourself, please go to
the yum faq at:
http://yum.baseurl.org/wiki/Faq
情况二解决办法
这个方法就是根据rpm包的方式安装，需要说明的我这个方法不一定是最好的， 但是时间有限， 已经耗费了大半天时间， 且即使是这种安装方式依旧会有坑，例如网上的教程大多是去网易的镜像地址去下载对应的rpm包，我依次下载之后到本地依旧是依赖报错，解决办法如下:
在开始之前需要知道你的系统版本以及位数:
[root@node02 local]# lsb_release -a # 没安装这个包,我在另一个节点 yum install redhat-lsb -y查看
LSB Version: :core-4.1-amd64:core-4.1-noarch:cxx-4.1-amd64:cxx-4.1-noarch:desktop-4.1-amd64:desktop-4.1-noarch:languages-4.1-amd64:languages-4.1-noarch:printing-4.1-amd64:printing-4.1-n
oarchDistributor ID: CentOS
Description: CentOS Linux release 7.8.2003 (Core)
Release: 7.8.2003
Codename: Core
[root@node02 local]# getconf LONG_BIT
64
7.8.2003 在下面的路径中会用到，x86_64是指指令集，后面的包名依据系统版本不同会有所不同，可以复制名称去
https://vault.centos.org/7.8.2003/os/x86_64/Packages/ 下查找最相近的，新建文件夹后需要下载的详细清单如下，如果你的系统版本以及位数正好与我相同，可以点击点击下载
mkdir py_rpm # 创建文件夹
cd py_rpm # 进入文件夹
# 复制下面的命令去命令行执行
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/lvm2-python-libs-2.02.186-7.el7.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/libxml2-python-2.9.1-6.el7.4.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-libs-2.7.5-88.el7.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-ipaddress-1.0.16-2.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-backports-1.0-8.el7.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-backports-ssl_match_hostname-3.5.0.1-1.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-2.7.5-88.el7.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-iniparse-0.4-9.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-pycurl-7.19.0-19.el7.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-urlgrabber-3.10-10.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-setuptools-0.9.8-7.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-kitchen-1.1.1-5.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/python-chardet-2.2.1-3.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/rpm-python-4.11.3-43.el7.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/yum-utils-1.1.31-53.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/yum-3.4.3-167.el7.centos.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/yum-plugin-aliases-1.1.31-53.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/yum-plugin-protectbase-1.1.31-53.el7.noarch.rpm
wget https://vault.centos.org/7.8.2003/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-53.el7.noarch.rpm
执行下面的命令安装:
rpm -Uvh --replacepkgs lvm2-python-libs*.rpm --nodeps --force
rpm -Uvh --replacepkgs libxml2-python*.rpm --nodeps --force
rpm -Uvh --replacepkgs python*.rpm --nodeps --force
rpm -Uvh --replacepkgs rpm-python*.rpm yum*.rpm --nodeps --force
$ rpm -Uvh --replacepkgs rpm-python*.rpm yum*.rpm --nodeps --force
准备中... ################################# [100%]
正在升级/安装...
1:yum-metadata-parser-1.1.4-10.el7 ################################# [ 14%]
2:rpm-python-4.11.3-43.el7 ################################# [ 29%]
3:yum-plugin-fastestmirror-1.1.31-5################################# [ 43%]
4:yum-3.4.3-167.el7.centos ################################# [ 57%]
5:yum-utils-1.1.31-53.el7 ################################# [ 71%]
6:yum-plugin-aliases-1.1.31-53.el7 ################################# [ 86%]
7:yum-plugin-protectbase-1.1.31-53.################################# [100%]
检验
$ python
Python 2.7.5 (default, Apr 2 2020, 13:16:51)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
$ yum install redhat-lsb -y
大功告成 !
