Environment

shebang

what is shebang: https://en.wikipedia.org/wiki/Shebang
why shebang: https://stackoverflow.com/questions/7670303/purpose-of-usr-bin-python3-shebang
difference between #!/usr/bin/python3 and #!/usr/bin/env python3: https://www.runoob.com/note/36514

conda create env

conda create -n <env> python==3.xx

conda remove env

conda remove -n <env> --all

coda change env python version

conda activate <env>
conda install python==3.xx

print python version

#! /usr/bin/bash
python -V
#! /use/bin/env python
import sys
print(sys.version)