Question

I’m writing a (somewhat) modular application in Python 3 and I’d like to run arbitrary programs from it, said program being specified at runtime and not necessarily a python script.

So I use for example,

subprocess.call([spam, "-i", eggs, "-o", ham])

If spam is a python script, with shebang to python3 and executable rights, I get

OSError: [Errno 8] Exec format error

if I

subprocess.call(["python3", spam, "-i", eggs, "-o", ham])

it works fine.

Do you know why? How can I run spam without specifying python3?

Answer 1

You need to use shell=True, and you need your array to be turned into a command string, like this:

subprocess.call(' '.join([spam, "-i", eggs, "-o", ham]), shell=True)

This will invoke the shell instead of the direct command, and the shell should be able to handle the shebang.