centos7: python2 和 python 3 并存

centos7 本身自带的是python2，但是因为系统本身有许多依赖于python2，现在直接装一个python3

首先安装依赖包

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

接下来与python官网下载python3

wget https://www.python.org/ftp/python/3.6.5/Python-3.6.5.tar.xz

然后解压缩

tar xvf Python-3.6.5.tar.xz

开始安装

cd Python-3.6.5.tar.xz
./configure --prefix=/usr/local/python3  (这里指安装到/usr/local目录下，创建一个为python3的安装目录)
make && make install

创建软连接

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

接下来在命令行中输入python3，即可。