The typical header should be
#!/usr/bin/env python
But I found below also works when executing the script like $python ./my_script.py
#!/usr/bin/python
#!python
What's difference between these 2 headers? What could be the problem for 2nd one? Please also discussing the case for python interpreter is in PATH or not. Thanks.
I'd suggest 3 things in the beginning of your script:
First, as already being said use environment:
#!/usr/bin/env python
Second, set your encoding:
# -*- coding: utf-8 -*-
Third, set some doc string:
"""This is a awesome
python script!"""
And for sure I would use " " (4 spaces) for ident.
Final header will look like:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""This is a awesome
python script!"""
Best wishes and happy coding.
The Python executable might be installed at a location other than /usr/bin, but env is nearly always present in that location so using /usr/bin/envis more portable.
From the manpage for env (GNU coreutils 6.10):
env - run a program in a modified environment
In theory you could use env to reset the environment (removing many of the existing environment variables) or add additional environment variables in the script header. Practically speaking, the two versions you mentioned are identical. (Though others have mentioned a good point: specifying python through env lets you abstractly specify python without knowing its path.)
Yes, there is - python may not be in /usr/bin, but for example in /usr/local/bin (BSD).
When using virtualenv, it may even be something like ~/projects/env/bin/python
The /usr/bin/env python becomes very useful when your scripts depend on environment settings for example using scripts which rely on python virtualenv. Each virtualenv has its own version of python binary which is required for adding packages installed in virtualenv to python path (without touching PYTHONPATH env).
As more and more people have started to used virtualenv for python development prefer to use /usr/bin/env python unless you don't want people to use their custom python binary.
Note: You should also understand that there are potential security issues (in multiuser environments) when you let people run your scripts in their custom environments. You can get some ideas from here.
Source: Stackoverflow.com