termux配置python开发环境

1.安装python
（1）安装python2并升级pip：

$ pkg install python2 -y
...
Collecting pip
Installing collected packages: setuptools, pip
Successfully installed pip-18.1 setuptools-40.6.2
$ python2 -m pip install --upgrade pip 

（2）安装python3并升级pip(不指定python版本，默认安装python3)
注意：python2在2020年元旦将停止维护，所以尽量使用python3开发。

$ pkg install python -y
……
Reading state information... Done
python is already the newest version (3.7.4-1).
0 upgraded, 0 newly installed, 0 to remove and 22 not upgraded.
$ python -m pip install --upgrade pip    
……
Successfully uninsta