官网下载Python源码包：
tar -zxvf Python-2.7.１３.tar.xz cd Python-2.7.１３ ./configure --prefix=/usr/local/python2.7.13 make make install
添加软连接：软连接必须是绝对路径（Too many levels of symbolic links错误）
ln -s /usr/local/python2.7.13/bin/python /usr/bin/python2.7.13
安装pip包：
tar -xvf pip-9.0.1.tar.gz
cd pip-9.0.1
python2.7.13 setup.py install # pip命令会自动安装到/usr/local/python2.7.13/bin/pip
ln -s /usr/local/python2.7.13/bin/pip /usr/bin/pip.2.7.13