how to run a python code from another python code

Question

I have multiple python codes in different folders which have to run in a sequence. There are similar questions asked before but, the answers do not seem to work out. i have tried the following commands:

subprocess.check_call(["Python", "D:/demo/full_alg.py"])
subprocess.check_output(["Python", "D:/demo/full_alg.py"])
os.system("D:/demo/full_alg.py")

That full_alg.py file, when executed must print out a list of files on which the code was executed and create corresponding tiff files

try by adding a `/` in front of `"D:/demo..."` like `/D:/demo/....` — Vikas Periyadath, Jan 23 '18 at 10:03
Possible duplicate of [What is the best way to call a Python script from another Python script?](https://stackoverflow.com/questions/1186789/what-is-the-best-way-to-call-a-python-script-from-another-python-script) — cyberbemon, Jan 23 '18 at 11:15
Following this method [My answer in another post](https://stackoverflow.com/questions/204017/how-do-i-execute-a-program-from-python-os-system-fails-due-to-spaces-in-path/48382727#48382727) — Benyamin Jafari, Jan 23 '18 at 11:23

sophros · Answer 1 · 2018-01-23T11:09:27.247

I am wondering why you are not trying to import full_alg.py package and based on the function calls in main consume the results of the call. How to precisely do it depends strongly on the contents of full_alg.py though.

If you insist on running a subprocess which runs another python script I suggest looking at multiprocessing module and the examples here.

The reasons why your code does not work may be Python interpreter missing from PATH. I would suggest passing the full path to both the interpreter you are using and the script. This should do in case of running a subprocess.check_call or subprocess.check_output. For the last one (os.system) I don't think it can run unless you set up python interpreter to be the default application for opening *.py files and even then it depends on the non-obvious configuration of the OS to run.

Thank you for suggesting that module but the examples define a function and then call the function in the main. I would like to know how do I call python script externally and execute it? — rao, Jan 23 '18 at 10:35

Benyamin Jafari · Accepted Answer · 2019-03-01T12:50:16.850

You can use subprocess library such as below:

import subprocess

args = ['{}/manage.py'.format('/home/<you>/<path>'), 'runserver']
subprocess.Popen(args, stdout=subprocess.PIPE)

Follow this method: My answer in another post

[UPDATE]:

This is an example with python3:

import subprocess

python_version = '3'
path_to_run = './'
py_name = '__main__.py'

# args = [f"python{python_version}", f"{path_to_run}{py_name}"]  # Available in python3
args = ["python{}".format(python_version), "{}{}".format(path_to_run, py_name)]

res = subprocess.Popen(args, stdout=subprocess.PIPE)
output, error_ = res.communicate()

if not error_:
    print(output)
else:
    print(error_)

how to run a python code from another python code

2 Answers2