1，本机python2.7升级到3.6

一般老的虚机安装时python默认时2.7版本，需要升级

]# which python
/usr/bin/python

ls -lah /usr/bin/python
lrwxrwxrwx. 1 root root 7 Apr 22 2020 /usr/bin/python -> python2

安装python3.6后：

ls -lah /usr/bin/ |grep python
lrwxrwxrwx. 1 root root 7 Apr 22 2020 python -> python2
lrwxrwxrwx. 1 root root 9 Apr 22 2020 python2 -> python2.7
-rwxr-xr-x. 1 root root 7.1K Oct 31 2018 python2.7
lrwxrwxrwx. 1 root root 9 Feb 10 16:46 python3 -> python3.6
-rwxr-xr-x. 2 root root 12K Nov 17 2020 python3.6
-rwxr-xr-x. 2 root root 12K Nov 17 2020 python3.6m

升级为python3.6过程：

 yum install epel-release
yum install python36
cd /usr/bin/
删除老软连接，创建新软连接
rm /usr/bin/python
ln -s /usr/bin/python3.6 /usr/bin/python
python --version