Run python script from another directory

Question

I feel a little foolish that I don't know this, but I tried to do it today and was surprised when it didn't work....

I have a directory C:\\test with a demo script, lets call it demo.py

1. If i am in C:\\test then I can just do python demo.py . Easy
2. I could also use a relative path, so from C:\\ , it's python test\\demo.py

What if C:\\test is on the path?

I was expecting to be able to now do python demo.py from anywhere however...

python: can't open file 'demo.py': [Errno 2] No such file or directory

I feel foolish because I thought this was straightforward, but I have searched around and have not found a solution. Am I fundamentally misunderstanding something here about how the Python interpreter finds scripts to run? I don't think this is anything to do with PYTHONPATH, as I understood that to relate to loading of modules inside scripts.

This is on Windows 7, by the way.

Answer 1

The PATH is only used to search for commands. A first way is that a Python script can be used directly as a command and in that case the PATH will be used: just use demo.py instead of python demo.py .

It will rely on OS specific ways. On Windows, file type (given by the extension - here .py) can be given default application to process them, while on Unix-like, the first line of a script can declare the program that will process it.

Alternatively, python allows to launch a module that will be searched in the PYTHONPATH ( not PATH) by using python -m module or for Windows py -m module .