centos安装Python3

一、安装思路
在不影响Python2的情况下安装Python3，做到以下几个步即可：
1、将Python2对应的命令改名
2、下载Python3包并且编译安装
3、在Python命令的目录下建立软链到Python3命令
4、修改yum与urlgrabber-ext-down 对应的Python头
二、实际操作
1、安装编译对应的依赖：

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

2、改名Python

    cd /usr/bin
    mv python python2.bak

3、下载并安装python3

    wget https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tar.xz
    tar -xf  Python-3.6.2.tar.xz
    cd Python-3.6.2
    ./configure prefix=/usr/local/python3
    make && make install

4、建立软链

    ln -s /usr/local/python3/bin/python3 /usr/bin/python

5、修改yum与urlgrabber-ext-down的Python头
将#! /usr/bin/python修改为#! /usr/bin/python2

vim /usr/bin/yum
vim /usr/libexec/urlgrabber-ext-down