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I have Python function that takes 1 arguments

def build_ibs(Nthreads,LibCfg):  # Nthreads is int,LibCfg as string
      import os  # module os must be imported
      import subprocess
      import sys

I use following in cmd.exe(on Win7) to call it

C:>cd C:\SVN\Python Code
C:\SVN\Python Code>C:\Python27\python.exe build_libs(4,'Release')

that throws error
enter image description here using following 

 C:>cd C:\SVN\Python Code
 C:\SVN\Python Code>C:\Python27\python.exe 4 'Release' # dosn't work
 C:\SVN\Python Code>C:\Python27\python.exe 4 Release   # dosn't work

does nothing, and no error is displayed even.

What is the correct way to call it both in cmd.exe or even Python shell command line?
Thanks

sedy

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2 Answers 2

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You can't just call a function from the command line - it must be inside a file. When you type python filename.py at the command line, what it does is feed the contents of filename.py into the Python interpreter with the namespace set to __main__.

So when you type Python.exe 4 'Release' it tries to find a file named 4. Since this file does not exist, Windows returns an Errno 2 - File not found.

Instead, put your code into a file - lets say test.py:

test.py:

def build_libs(Nthreads,LibCfg):  # Nthreads is int,LibCfg as string
      import os  # module os must be imported
      import subprocess
      import sys
      # ...

if __name__=='__main__':
    numthreads = sys.argv[1] # first argument to script - 4
    libconfig = sys.argv[2] # second argument
    # call build_libs however you planned
    build_libs(numthreads, libconfig)

Then run from the command line: C:\Python27\python.exe test.py 4 Release In the directory that test.py is saved in.

Update: If you need to use build_libs in multiple files, it's best to define it in a module, and then import it. For example:

mod_libs/__init__.py - empty file

mod_libs/core.py:

def build_libs(...):
    ....
    # function definition goes here

test.py:

import sys
import mod_libs
if __name__ == '__main__':
    mod_libs.build_libs(sys.argv[1], sys.argv[2])
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2 Comments

Thanks Aaron, it works and I also got the idea.However, if there were many files that needed to use build_libs then, calling it from within other files would be better than rewriting function definition again and again? in such case, assuming build_libs is put into a package and imported, would function call remain same as you have shown above?
Yeah, you can put it into a Python module. I edited the answer to show how you might do that.
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  1. If you want to use Python code as in your first attempt, you need to start the Python interpreter.
  2. If you want to call a Python function from your OS's command line as in your second attempt, you need to use the proper modules (like sys.argv or argparse).

For example:

C:\SVN\Python Code> py
Python 3.4.2 (v3.4.2:ab2c023a9432, Oct  6 2014, 22:16:31) [MSC v.1600 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import build_libs
>>> build_libs.build_libs(4, 'Release')

Or, in your build_libs.py, import the sys module at the top of the script, and then run the function based on its arguments at the end of the script:

import sys

...

print(build_libs(int(sys.argv[1]), sys.argv[2]))

Then at your OS's command line:

C:\SVN\Python Code> py build_libs 4 Release
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1 Comment

Tigerhawk,I tried this but did not work. I have updated question too.

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