os.getenv returns None instead correct value

Question

I have a complex piece of software I am not able to post, nor do I have a concrete working example. I will try to explain the problem, maybe someone encountered this before.

On the Linux shell I have defined an environment variable:

> export MY_TEST_ENV=4711
> echo $MY_TEST_ENV
> 4711

Within the complex code I want to obtain this variable with

print os.getenv('MY_TEST_ENV')

which always returns None. If I create a test-script to test this behavior, even with classes in different files, I always get the desired behavior, e.g., os.getenv('MY_TEST_ENV') returns the correct value 4711.

The code is started with sudo.

Any ideas what could be the reason?

Answer 1

Most likely the way you invoke the Python process makes you lose the environment. If you export the variable within a running shell and, directly after that, invoke the Python process in question in the same shell, this environment variable should definitely be available to this Python process. To help you debugging this issue: instead of the code in question (print os.getenv('my...')), print the whole environment via print os.environ. From the result you should be able to infer what happened to your environment.