centos7.4出现yum command not found

购买的云服务器运行yum命令出现yum command not found。

通过将云主机自带的yum和python卸载掉，并且同时需要关注/usr/bin/yum文件的首行解释。我定义其为"#!/usr/bin/python"

1.卸载python:

 rpm -qa|grep python|xargs rpm -e --allmatches --nodeps
 whereis python|xargs rm -fr

2.卸载yum:

 rpm -qa|grep yum|xargs rpm -e --allmatches --nodeps
 rm -rf /etc/yum.repos.d/*
 whereis yum|xargs rm -fr

3.创建目录python和yum用以存放rpm包：

 mkdir /usr/local/src/python
2 mkdir /usr/local/src/yum

4.使用wget分别下载python以及yum的rpm包（注意：一定要和系统的版本号对应）

（1）下载python的rpm包：

 #cd /usr/local/src/python 进入目录

 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/python-2.7.5-34.el7.x86_64.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/python-iniparse-0.4-9.el7.noarch.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/python-pycurl-7.19.0-17.el7.x86_64.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/python-devel-2.7.5-34.el7.x86_64.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/python-libs-2.7.5-34.el7.x86_64.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/python-urlgrabber-3.10-7.el7.noarch.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/rpm-python-4.11.3-17.el7.x86_64.rpm

（2）下载yum的rpm包：

 #cd /usr/local/src/yum 

 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/yum-3.4.3-132.el7.centos.0.1.noarch.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
 #wget http://vault.centos.org/7.2.1511/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-34.el7.noarch.rpm

5.安装python以及yum的rpm包

（1）安装python:

 #cd /usr/local/src/python 

 #rpm -ivh python-* rpm-python-*
   出现安装包的依赖问题，此时如下解决即可：

 #rpm -ivh python-* rpm-python-* --nodeps --force
             --nodeps --force为不考虑依赖包，强制安装。

             安装完后即可运行python:

（2）安装yum:

 #cd /usr/local/src/yum
 #rpm -ivh yum-*