CODEWITHSUNDEEP
pythonpython-2.7subprocesspopen
TheCodeCache
TheCodeCache

Reputation: 962

How to fork a child process in python by passing all its dependency

I've a python file, say A.py which depends upon several other packages/folders/files let's call them B.py, C.py, D.py etc. and these are residing in some different location than A.py

A.py contents::

import B, C, D
//other codes

and I am calling A.py from another python script, let's call it 1.py

1.py contents:

child_process = subprocess.Popen("python A.py", shell=True)

And I run 1.py like this in command line: python 1.py

my question is how to pass a series of dependencies, in this case, B.py, C.py, D.py to A.py in the child process to run it successfully.

I am using python 2.7

Upvotes: 0

Views: 1287

Answers (1)

Giacomo Alzetta
Giacomo Alzetta

Reputation: 2479

You should correctly install B/C/D files in the python path. Alternatively you can use the PYTHONPATH environmental variable:

child_process = subprocess.Popen(['python', 'A.py'], env={'PYTHONPATH': '/path/to/the/directory'})

Where /path/to/the/directory is the path to the directory containing B, C and D.

Depending on what A.py does you may need to pass also some more of the environment. This can be achieved by either:

  • setting the env variable in the parent process and let the child process inherit it:

    import os
os.environ['PYTHONPATH'] = '/path/...'
Popen(['python', 'A.py'])   # by default it inherits parent env

  • or copy the parent environment:

    new_env = dict(os.environ) # make a copy
new_env['PYTHONPATH']  = '/path/...'
Popen(['python', 'A.py', env=new_env)

Note: using shell=True is a security hazard. Also it is useless and less efficient. you should avoid it and pass the command line as a list of strings.

Upvotes: 2

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