Question

I am experiencing an odd problem that I’m not quite sure how to tackle. I have a Python-selenium script that uses relative paths to log results to a text-file.

Here is the part of the script which sets up the log-file:

log_file = './demo-logfiles/log_file_template.txt'
sys.stdout = open('log_file_template.txt', 'a',)

As you can see, it uses a relative path to a folder. If I run this script as:
python demo.py firefox MAC, it runs flawlessly and the logfile gets sent to the proper folder.

If I run this exact Python script from within a larger shell-script, it returns an error that the './demo-logfiles/log_file_template.txt' doesn’t exist.

I have found that if I change the script to '../demo-logfiles/log_file_template.txt' it works in the larger shell script, but stops working if I run it normally.

It either works in one, or the other. What is the reason for the relative directories being interpreted in different ways? I would not like to have two separate scripts for running in Python/shell.

The original python script is in the directory /blah/blah/DEMO/demo.py, and the the shell script that runs it is in /blah/blah/DEMO/demo-autotest/autotest_logger.sh

I have confirmed that this problem occurs for any script I try to run. I shouldn’t have to change the original Python code to make it work with the shell script. I already accounted for it in the shell script, and it successfully runs the file.

Thanks.

Answer 1

You should never use a “.” (or any relative path) in a directory path in a script unless you really mean you want to refer to the directory that the user is running the script from. If you want to refer to a location relative to the script that’s running, you can do the following:

import os
import sys
directory = os.path.dirname(os.path.abspath(__file__))
sys.stdout = open(os.path.join(directory, "demo-logfiles", "log_file_template.txt"), "a")

Best practices side note: you should probably use the logging module rather than reassigning sys.stdout.