前提有python2，这个不要删，我们再装一个python3
首先安装依赖包
yum -y groupinstall "Development tools"
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创建Python目录
mkdir python3
cd python3/下载Python3.7.4
wget https://www.python.org/ftp/python/3.7.4/Python-3.7.4.tar.xz
然后解压压缩包，进入该目录，安装Python3
xz -d Python-3.7.4.tar.xz
tar xvf Python-3.7.4.tar
cd Python-3.7.4/
./configure --prefix=/python3（这里是之前我在/目录下创建了一个python3目录）
make && make install安装成功。创建软链
ln -s /python3/bin/python3 /usr/bin/python3
ln -s /python3/bin/pip3 /usr/bin/pip3完成
