return value from one python script to another

Question

I have two files: script1.py and script2.py. I need to invoke script2.py from script1.py and return the value from script2.py back to script1.py. But the catch is script1.py actually runs script2.py through os.

script1.py:

import os
print(os.system("script2.py 34"))

script2.py

import sys
def main():
    x="Hello World"+str(sys.argv[1])
    return x

if __name__ == "__main__":
    x= main()

As you can see, I am able to get the value into script2, but not back to script1. How can I do that? NOTE: script2.py HAS to be called as if its a commandline execution. Thats why I am using os.

What should be returned from script2.py? Is return code sufficient? — Łukasz Rogalski
– Łukasz Rogalski, Commented Jun 5, 2015 at 10:33
I want the value x to be returned. In this case script2 should return "Hello World 34" — codingsplash
– codingsplash, Commented Jun 5, 2015 at 10:35

Łukasz Rogalski · Accepted Answer · 2015-06-05 11:28:39Z

20

Ok, if I understand you correctly you want to:

pass an argument to another script
retrieve an output from another script to original caller

I'll recommend using subprocess module. Easiest way would be to use check_output() function.

Run command with arguments and return its output as a byte string.

Sample solution:

script1.py

import sys
import subprocess
s2_out = subprocess.check_output([sys.executable, "script2.py", "34"])
print s2_out

script2.py:

import sys
def main(arg):
    print("Hello World"+arg)

if __name__ == "__main__":
    main(sys.argv[1])

edited Jun 5, 2015 at 11:28

answered Jun 5, 2015 at 10:40

Łukasz Rogalski

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3 Comments

codingsplash Over a year ago

Thanks! But I get an TypeError: argument of type 'int' is not iterable error. Is it because of the python version? I am using 3.4

Łukasz Rogalski Over a year ago

@user567 sorry, you have to pass 34 as string. I'll edit an answer.

Thu Ra Over a year ago

@Łukasz Rogalski, how can I validate the s2_out if print(1) in script2.py?

Community · Accepted Answer · 2017-05-23 10:30:11Z

12

The recommended way to return a value from one python "script" to another is to import the script as a Python module and call the functions directly:

import another_module

value = another_module.get_value(34)

where another_module.py is:

#!/usr/bin/env python
def get_value(*args):
    return "Hello World " + ":".join(map(str, args))

def main(argv):
    print(get_value(*argv[1:]))

if __name__ == "__main__":
    import sys
    main(sys.argv)

You could both import another_module and run it as a script from the command-line. If you don't need to run it as a command-line script then you could remove main() function and if __name__ == "__main__" block.

See also, Call python script with input with in a python script using subprocess.

edited May 23, 2017 at 10:30

CommunityBot

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answered Jun 5, 2015 at 12:02

jfs

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