centos7 默認安裝 python2.7
1.先安裝python36和對應pip
yum install python-pip #安裝python2的pip yum install python36 yum install python36-pip
2.修改軟鏈接
（1）軟鏈接由python2變成python3
ln -snf python3 python
（2）pip默認成python3的
mv pip pip.bak ln -snf pip3 pip
3.修改#！文件
yum和urlgrabber-ext-down 需要依賴Python2
vim /usr/bin/yum vim /usr/libexec/urlgrabber-ext-down
都改成 #! /usr/bin/python2.7
手動安裝的軟件一般在此目錄下
/usr/local