Python subprocess using import subprocess

Question

Can this be somehow overcome? Can a child process create a subprocess?

The problem is, I have a ready application which needs to call a Python script. This script on its own works perfectly, but it needs to call existing shell scripts.

Schematically the problem is in the following code:

parent.py

import subprocess
subprocess.call(['/usr/sfw/bin/python', '/usr/apps/openet/bmsystest/relAuto/variousSW/child.py','1', '2'])

child.py

import sys
import subprocess
print sys.argv[0]
print sys.argv[1]

subprocess.call(['ls -l'], shell=True)
exit

Running child.py

python child.py 1 2
  all is ok

Running parent.py

python  parent.py
Traceback (most recent call last):
  File "/usr/apps/openet/bmsystest/relAuto/variousSW/child.py", line 2, in ?
    import subprocess
ImportError: No module named subprocess

Answer 1

There should be nothing stopping you from using subprocess in both child.py and parent.py

I am able to run it perfectly fine. :)

Issue Debugging :

You are using python and /usr/sfw/bin/python .

1. Is bare python pointing to the same python?
2. Can you check by typing 'which python'?

I am sure if you did the following, it will work for you.

/usr/sfw/bin/python parent.py

Alternatively, Can you change your parent.py code to

import subprocess
subprocess.call(['python', '/usr/apps/openet/bmsystest/relAuto/variousSW/child.py','1', '2'])

Answer 2

You can try to add your python directory to sys.path in chield.py

import sys
sys.path.append('../')

Yes, it's bad way, but it can help you.

Answer 3

Using subprocess.call is not the proper way to do it. In my view, subprocess.Popen would be better.

parent.py:

1 import subprocess
2 
3 process = subprocess.Popen(['python', './child.py', 'arg1', 'arg2'],\
4         stdin=subprocess.PIPE, stdout=subprocess.PIPE,\
5         stderr=subprocess.PIPE)
6 process.wait()
7 print process.stdout.read()

child.py

1 import subprocess
2 import sys
3 
4 print sys.argv[1:]
5 
6 process = subprocess.Popen(['ls', '-a'], stdout = subprocess.PIPE)
7 
8 process.wait()
9 print process.stdout.read()

Out of program:

python parent.py 
['arg1', 'arg2']
.
..
chid.py
child.py
.child.py.swp
parent.py
.ropeproject