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Mr. T
Asked: 2022-05-06 17:16:39 +0800 CST

Python script called by udev rule unable to import modules ModuleNotFound

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I have a udev rule which triggers a python script whenever a block device (USB drive) is attached/detached from the system. The udev rule seems to be firing correctly, but the python script it calls cant start because it's missing an import. The import error I get it ModuleNotFound error. The udev script calls a bash script which calls: python3 /root/projects/script.py --arg "$1" --arg2 >> /tmp/python3.log 2>&1 &

In python3.log, I see the error: ModuleNotFoundError: No module named 'requests'

I have installed this module as root via pip3 install requests, and indeed the script works fine when manually called from the root shell, but somehow being called by udev doesn't work.

If I run from root terminal pip3 install requests I get Requirement already satisfied: requests in /usr/local/lib/python3.9/dist-packages (2.27.1)

I assume this is a pathing issue? How do I go about figuring out why python can't find this module?

python

1 Answers

  1. The problem is the way python determines it's "path". I don't know the best practice solution for this, but here's what I did. From a python console that does work (sudo python3) I do import requests then print(requests) to get the full path. This gives me <module 'requests' from '/usr/local/lib/python3.9/dist-packages/requests/__init__.py'>

    So in my script.py I add this to the top

    import os
import sys
sys.path.append(os.path.abspath("/usr/local/lib/python3.9/dist-packages"))

    And the issue is solved

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