1.查看一下python2在哪个目录

whereis python
cd /usr/bin
ll python*

2.安装python3所需要的依赖包

yum install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gcc make libffi-devel

3.安装pip

yum -y install epel-release 
yum install python-pip

4.下载python3源码包

wget https://www.python.org/ftp/python/3.7.0/Python-3.7.0.tgz

###5.解压缩

tar -zxvf Python-3.7.0.tgz

6.切换至解压后的目录，编译安装源码包

./configure prefix=/usr/local/python3 
make && make install

7.添加python3的软链接及pip3 的软链接

ln -s /usr/local/python3/bin/python3.7 /usr/bin/python3.7 
ln -s /usr/local/python3/bin/pip3.7 /usr/bin/pip3.7

###8.测试是否安装成功了

python -V

9.更改yum配置，因为其要用到python2才能执行，否则会导致yum不能正常使用

vi /usr/bin/yum 
把 #! /usr/bin/python 修改为 #! /usr/bin/python2 
vi /usr/libexec/urlgrabber-ext-down 
把 #! /usr/bin/python 修改为 #! /usr/bin/python2