How to Walk Directory Tree in Python Using os.walk

Use the os.walk() function in Python to walk through a directory tree. It yields a tuple with the current directory path, a list of subdirectories, and a list of files, allowing you to process each folder and file step-by-step.

Syntax

The os.walk() function is used to generate the file names in a directory tree by walking either top-down or bottom-up.

• os.walk(top, topdown=True, onerror=None, followlinks=False)
• top: The root directory path to start walking from.
• topdown: If True, directories are scanned from top to bottom; if False, from bottom to top.
• onerror: Optional function called with an OSError instance if an error occurs.
• followlinks: If True, symbolic links to directories are followed.

It returns a generator yielding tuples: (dirpath, dirnames, filenames).

python

import os

for dirpath, dirnames, filenames in os.walk('path/to/start'):
    print(f'Current directory: {dirpath}')
    print(f'Subdirectories: {dirnames}')
    print(f'Files: {filenames}')
    print('---')

Example

This example walks through the current directory and prints all folders and files it finds. It shows how to access each part of the directory tree step-by-step.

python

import os

start_path = '.'  # current directory

for dirpath, dirnames, filenames in os.walk(start_path):
    print(f'Found directory: {dirpath}')
    for dirname in dirnames:
        print(f'  Subdirectory: {dirname}')
    for filename in filenames:
        print(f'  File: {filename}')

Output

Found directory: .
  Subdirectory: folder1
  Subdirectory: folder2
  File: file1.txt
  File: file2.py
Found directory: ./folder1
  File: file3.txt
Found directory: ./folder2
  Subdirectory: subfolder
Found directory: ./folder2/subfolder
  File: file4.txt

Common Pitfalls

• Not using the correct path for os.walk() can cause no output or errors.
• Modifying dirnames inside the loop affects which directories are walked.
• Forgetting that os.walk() returns a generator, so you must iterate it to get results.
• Not handling symbolic links properly can cause infinite loops if followlinks=True.

Example of filtering out hidden directories:

python

import os

start_path = '.'

for dirpath, dirnames, filenames in os.walk(start_path):
    # Remove hidden directories from traversal
    dirnames[:] = [d for d in dirnames if not d.startswith('.')]
    print(f'Walking: {dirpath}')
    print(f'Directories: {dirnames}')
    print(f'Files: {filenames}')

Quick Reference

• os.walk(path): Walk directory tree from path.
• Yields (dirpath, dirnames, filenames).
• Modify dirnames to control traversal.
• Use topdown=True to process parent folders before children.
• Set followlinks=True to follow symbolic links carefully.

Key Takeaways

Use os.walk() to recursively traverse directories and files easily.

os.walk() yields a tuple with current path, subdirectories, and files for each folder.

Modify the dirnames list inside the loop to skip or control which folders to visit.

Be careful with symbolic links to avoid infinite loops when following them.

Always provide the correct starting path to os.walk() for expected results.