Linux-Debian: How to solve “[Errno 13] – Permission denied“ when starting Python-script through rc.local?

Question

For finishing my school’s final assignment, I currently am trying to automatically run the following .py-file (createTXT.py) on my Linux Debian 11 after reboot:

import os
from os import listdir
from os.path import isfile, join

#dateiPfad = os.getcwd()
dateiPfad = "/test_csv/"

filenames = [f for f in listdir(dateiPfad) if isfile(join(dateiPfad, f))]

i = 0

for file in range(len(filenames)):

    i = i + 1

with open('text'+str(i)+'.txt', 'w') as f:
    f.write('Create a new text file!')

The code I want to run works perfectly fine when being executed via “python3 createTXT.py”.

I created /etc/rc.local, made it executable etc. This is what it looks like:

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

sleep 10 && sudo -H -u myuser /usr/bin/python3 /python_skript/createTXT.py

exit 0

When I try to run it using “Sudo systemctl start rc-local” the following error regarding a permission denied pops up:

$ sudo systemctl status rc-local
● rc-local.service - /etc/rc.local Compatibility
 Loaded: loaded (/lib/systemd/system/rc-    local.service; enabled-runtime; vendor preset: enabled)
Drop-In: /usr/lib/systemd/system/rc-local.service.d
         └─debian.conf
 Active: failed (Result: exit-code) since Tue 2022-    01-25 09:17:38 CET; 4s ago
   Docs: man:systemd-rc-local-generator(8)
Process: 9426 ExecStart=/etc/rc.local start (code=exited, status=1/FAILURE)
    CPU: 52ms

Jan 25 09:17:38 UP-debian sudo[9467]:     root : PWD=/ ; USER=myuser ; COMMAND=/usr/bin/python3 /python_skript/createTXT.py
Jan 25 09:17:38 UP-debian sudo[9467]: pam_unix(sudo:session): session opened for user myuser(uid=1000) by (uid=0)
Jan 25 09:17:38 UP-debian rc.local[9468]: Traceback (most recent call last):
Jan 25 09:17:38 UP-debian rc.local[9468]:   File "/python_skript/createTXT.py", line 19, in <module>
Jan 25 09:17:38 UP-debian rc.local[9468]:     with open('text'+str(i)+'.txt', 'w') as f:
Jan 25 09:17:38 UP-debian rc.local[9468]: PermissionError: [Errno 13] Permission denied: 'text16.txt'
Jan 25 09:17:38 UP-debian sudo[9467]: pam_unix(sudo:session): session closed for user myuser
Jan 25 09:17:38 UP-debian systemd[1]: rc-local.service: Control process exited, code=exited, status=1/FAILURE
Jan 25 09:17:38 UP-debian systemd[1]: rc-local.service: Failed with result 'exit-code'.
Jan 25 09:17:38 UP-debian systemd[1]: Failed to start /etc/rc.local Compatibility.

This is what I tried so far:

1. Ran “sudo chmod 777 /test_csv” (the path the py-script is located)
2. Changed user to : sudo chown -R myuser:myuser /test_csv
3. Changed user back to root: sudo chown -R root:root /test_csv
4. Made „#!/usr/src“ the first line in the .py-script
5. Made #! /usr/bin/env python3“ the first line in the .py-script
6. Added „sleep 10 &&“ --> sleep 10 && sudo -H -u myuser /usr/bin/python3 /python_skript/createTXT.py
7. Ran “sudo chmod 755 /test_csv”

Unfortunately, nothing helped. I also tried using cronetab before but this didn’t work either.

Do you have any further ideas what could solve my problem?