CODEWITHSUNDEEP
pythonlinux
Nathan
Nathan

Reputation: 78439

Getting return information from another python script

I'm on linux, and I have one python script that I want to call from another python script. I don't want to import it as a module (for a layer of security, and now for an academic exercise because I want to figure this out), I want to actually have one script call the other with os.system() or another function like that, and have the other script return a list of tuples to the first script.

I know this might not be the optimal way to do it, but I'd like to try it out, and learn some stuff in the process.

Upvotes: 4

Views: 3218

Answers (5)

Avid Coder
Avid Coder

Reputation: 18387

It's very simple.

import popen2
fout, fin = popen2.popen2('python your_python_script.py')
data = fout.readline().strip()
if data <> '':
    # you have your `data`, so do something with it

Upvotes: 0

jfs
jfs

Reputation: 414149

Importing a module is different from executing it as a script. If you don't trust the child Python script; you shouldn't run any code from it.

A regular way to use some code from another Python module:

import another_module

result = another_module.some_function(args)

If you want to execute it instead of importing:

namespace = {'args': [1,2,3]} # define __name__, __file__ if necessary
execfile('some_script.py', namespace)
result = namespace['result']

execfile() is used very rarely in Python. It might be useful in a debugger, a profiler, or to run setup.py in tools such as pip, easy_install.

See also runpy module.

If another script is executed in a different process; you could use many IPC methods. The simplest way is just pipe serialized (Python objects converted to a bytestring) input args into subprocess' stdin and read the result back from its stdout as suggested by @kirelagin:

import json
import sys
from subprocess import Popen, PIPE

marshal, unmarshal = json.dumps, json.loads

p = Popen([sys.executable, 'some_script.py'], stdin=PIPE, stdout=PIPE)
result = unmarshal(p.communicate(marshal(args))[0])

where some_script.py could be:

#!/usr/bin/env python
import json
import sys

args = json.load(sys.stdin)   # read input data from stdin
result = [x*x for x in args]  # compute result
json.dump(result, sys.stdout) # write result to stdout

Upvotes: 3

ScotchAndSoda
ScotchAndSoda

Reputation: 4171

You know, ZMQ is very useful for inter proces communication. You can well use it with json objects.

Here is the python binding

Upvotes: 1

kirelagin
kirelagin

Reputation: 13616

You will need some kind of serialization to return a list. I'd suggest pickle or JSON.

Your other script will print it to stdout and the calling script will read it back and deserialize.

Upvotes: 2

Simeon Visser
Simeon Visser

Reputation: 122336

You can use subprocess:

subprocess.call(["python", "myscript.py"])

This will also return the process return value (such as 0 or 1).

Upvotes: 4

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