How to Use os.walk in Python: Syntax and Examples

Use os.walk(path) to generate file names in a directory tree by walking either top-down or bottom-up. It returns a tuple with the current directory path, a list of directories, and a list of files for each directory it visits.

Syntax

The os.walk() function is called with a directory path and returns an iterator that yields tuples. Each tuple contains three parts:

• root: the current directory path being scanned
• dirs: a list of subdirectories in root
• files: a list of files in root

You can loop over this iterator to access all files and folders in the directory tree.

python

import os

for root, dirs, files in os.walk('your_directory_path'):
    print(f'Current directory: {root}')
    print(f'Subdirectories: {dirs}')
    print(f'Files: {files}')
    print('---')

Example

This example shows how to use os.walk to print all files with their full paths inside a directory and its subdirectories.

python

import os

def list_all_files(directory):
    for root, dirs, files in os.walk(directory):
        for file in files:
            full_path = os.path.join(root, file)
            print(full_path)

# Replace 'test_folder' with your folder path
list_all_files('test_folder')

Output

test_folder/file1.txt
test_folder/subfolder/file2.txt
test_folder/subfolder/file3.txt

Common Pitfalls

Some common mistakes when using os.walk include:

• Not joining root and file names to get full file paths.
• Modifying the dirs list inside the loop incorrectly, which can affect traversal.
• Assuming the order of files or directories is sorted; os.walk does not guarantee order.

Always use os.path.join(root, file) to get the correct full path.

python

import os

# Wrong way: printing file names without full path
for root, dirs, files in os.walk('test_folder'):
    for file in files:
        print(file)  # This prints only file names, not full paths

# Right way: join root and file
for root, dirs, files in os.walk('test_folder'):
    for file in files:
        print(os.path.join(root, file))

Quick Reference

Key points to remember when using os.walk:

• Returns tuples: (root, dirs, files)
• Walks directory tree top-down by default
• Modify dirs list to control traversal
• Use os.path.join(root, name) to get full paths

Key Takeaways

Use os.walk to iterate over directories and files recursively.

Each iteration returns the current directory path, subdirectories, and files.

Always join root and file names to get full file paths.

Modify the dirs list carefully to control which subdirectories are visited.

os.walk does not guarantee sorted order of files or directories.