Question

I was wondering how I would redirect the output of a program I would run with subprocess.Popen to the program I am using. For example, if I’m executing a script from Python ImageProcessing.py in.jpeg out.jpeg, I would like to instead do some extra processing in the higher level script; meaning that I would like the python code to replace out.jpeg with a pipe or some other sort of communication. (Also, yes I know it would be better to import in most cases, in this case I rather not).

Thank you in advance!

Answer 1

You can use the stdout=subprocess.PIPE argument to Popen. The stdout of the subprocess is a normal file. Example:

import subprocess

p = subprocess.Popen(["/bin/cat", "hello.txt"], stdout=subprocess.PIPE)

for line in p.stdout:
    print("PIPE OUT [%s]" % line)