注意：文章最后结果是python3.x与系统原有python2.x共存，因为有系统命令依赖于python2.x
一、安装python3.x所需要的依赖包
yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel
二、创建安装目录
mkdir -p /usr/local/python3
cd /usr/local/python3
三、下载Python3.6.8(下载过程可能略慢)
wget https://www.python.org/ftp/python/3.6.8/Python-3.6.8.tar.xz
四、解压编译安装
tar -xvf Python-3.6.8.tar.xz
cd Python-3.6.8/
./configure --prefix=/usr/local/python3
make &&make instal
五、创建软连接;注意不要覆盖原有的python命令
ln -s /usr/local/python3/bin/python3 /usr/bin/python3
ln -s /usr/local/python3/bin/pip3 /usr/bin/pip3
废话重复一遍: 不建议覆盖原有python，然后去修改如环境变量或yum命令的python，可能会有莫名其妙的问题
