Question

I found this post on stackoverflow which was exactly what I wanted to integrate into a larger script I am writing: Find the newest folder in a directory in Python

I want to check for the newest file or folder so modified the script for testing as follows:

#!/usr/bin/env python3.1

import os

def allFilesIn(b='.'):
    result = []
    for d in os.listdir(b):
        bd = os.path.join(b, d)
    result.append(bd)
    return result

latest_subdir = max(allFilesIn('/tmp/testforlatest'), key=os.path.getmtime)

print(latest_subdir)

However I get results as follows:

> touch /tmp/testforlatest/file1
> ls -t -1 /tmp/testforlatest/ | head -1
file1
> /tmp/testfornewestfile.py 
/tmp/testforlatest/file1
> touch /tmp/testforlatest/file2
> ls -t -1 /tmp/testforlatest/ | head -1
file2
> /tmp/testfornewestfile.py 
/tmp/testforlatest/file1
> mkdir /tmp/testforlatest/folder1
> ls -t -1 /tmp/testforlatest/ | head -1
folder1/
> /tmp/testfornewestfile.py 
/tmp/testforlatest/folder1
> mkdir /tmp/testforlatest/folder2
> ls -t -1 /tmp/testforlatest/ | head -1
folder2/
> /tmp/testfornewestfile.py 
/tmp/testforlatest/folder1
> touch /tmp/testforlatest/file3
> ls -t -1 /tmp/testforlatest/ | head -1
file3
> /tmp/testfornewestfile.py 
/tmp/testforlatest/folder1

Would someone mind explaining why this is happening and what I’m doing wrong.

other information which may be of use:

> python3.1 --version
Python 3.1.3
> cat /etc/debian_version 
6.0.2

Answer 1

Your function allFilesIn only returns the last file returned by os.listdir because you append the results outside of the for loop. You probably meant this:

def allFilesIn(b='.'):
    result = []
    for d in os.listdir(b):
        bd = os.path.join(b, d)
        result.append(bd)
    return result

As an aside it’s preferable to use lowercase and underscores for function names per PEP8. You could also condense the function into a list comprehension pretty easily:

def all_files_in(path='.'):
    return [os.path.join(path, f) for f in os.listdir(path)]