Centos7下python2.7升级至3.6：
1.下载python3.6：
wget https://www.python.org/ftp/python/3.6.4/Python-3.6.4.tgz
2.解压：
tar -xzf Python-3.6.4.tgz
3.安装：
cd Python-3.6.4
./configure --prefix=/usr/local/python3.6
make
make install
4.备份:
mv /usr/bin/python /usr/bin/python2.7.5
5.修改软连接:
ln -fs /usr/local/python3.6/bin/python3.6 /usr/bin/python
ln -fs /usr/local/python3.6/bin/pip3.6 /usr/bin/pip
6.验证：
python -V
pip -V
7.修改yum文件：
vi /usr/bin/yum
vi /usr/libexec/urlgrabber-ext-down
第一行改为:#!/usr/bin/python2.7
8.升级：
python -m pip install --upgrade pip
