📁 Section 13: Working Directories

📁 Learn how to manipulate directories in Python using the os module. This includes getting and changing the current working directory, creating, renaming, and deleting directories, listing files, and traversing directory trees.

This section will help you interact with your file system in a cross-platform way — ideal for automation scripts, data processing, and file management tasks.

🧠 What You'll Learn

• 📍 How to get and change the current working directory
• 🔗 Use os.path.join() and os.path.split() for cross-platform path handling
• 📂 Check if a path is a valid directory
• ➕ Create new directories safely
• 🔄 Rename directories
• 🗑️ Delete empty directories
• 🔍 Traverse directory contents recursively using os.walk()
• 📋 List all files (or specific types) from a directory and its subdirectories
• 💡 Hidden tips and best practices for working with directories in Python

📍 Get Current Working Directory

Use os.getcwd() to find out where your script is currently running.

🔹 Example:

import os

cwd = os.getcwd()
print(f"Current Working Directory: {cwd}")

🔸 This is useful when working with relative paths or debugging file access issues.

🔄 Change Working Directory

Use os.chdir(path) to switch to a different directory.

🔹 Example:

os.chdir('/script')
print(os.getcwd())  # Output: /script

⚠️ If the target directory doesn’t exist, it raises a FileNotFoundError.

🔗 Join and Split Paths

Use os.path.join() to build paths that work across Windows, macOS, and Linux.

🔹 Join Example:

import os

path = os.path.join('data', 'files', 'input.txt')
print(path)
# Output: data/files/input.txt (Linux/macOS) or data\files\input.txt (Windows)

🔹 Split Example:

parts = os.path.split(path)
print(parts)  # ('data/files', 'input.txt') or ('data\\files', 'input.txt')

💡 Always use these functions instead of hardcoding slashes (/ or \) to ensure compatibility.

🔍 Test If a Path Is a Directory

Use os.path.exists() and os.path.isdir() to check if a path exists and is a directory.

🔹 Example:

dir_path = os.path.join("C:\\", "temp")

if os.path.exists(dir_path) and os.path.isdir(dir_path):
    print(f"{dir_path} is a valid directory.")
else:
    print(f"{dir_path} is not a valid directory.")

🔸 These checks prevent errors when trying to access non-existent or invalid paths.

➕ Create a New Directory

Use os.mkdir() to create a new directory.

🔹 Best Practice – Only create if it doesn't exist:

dir = os.path.join("C:\\", "temp", "python")
if not os.path.exists(dir):
    os.mkdir(dir)
    print(f"Directory '{dir}' created.")

🔸 To create nested directories at once, use os.makedirs():

os.makedirs(os.path.join("project", "data", "raw"), exist_ok=True)

🔄 Rename a Directory

Use os.rename(old_path, new_path) to rename or move a directory.

🔹 Example:

old_dir = os.path.join("C:\\", "temp", "python")
new_dir = os.path.join("C:\\", "temp", "python3")

if os.path.exists(old_dir) and not os.path.exists(new_dir):
    os.rename(old_dir, new_dir)
    print(f"'{old_dir}' was renamed to '{new_dir}'")

⚠️ If the new name already exists, it raises a FileExistsError.

🗑️ Delete a Directory

Use os.rmdir(path) to delete an empty directory.

🔹 Example:

dir = os.path.join("C:\\", "temp", "python")
if os.path.exists(dir):
    os.rmdir(dir)
    print(f"{dir} has been removed.")

🔸 To delete a directory and all its contents, use shutil.rmtree():

import shutil

shutil.rmtree(dir)  # Removes directory even if not empty

🔍 Traverse a Directory Tree Recursively

Use os.walk() to traverse directories and list files/subdirectories.

🔹 Example – Print all files and folders:

for root, dirs, files in os.walk("c:\\temp"):
    print(f"{root} has {len(files)} files")

🔸 This function is essential for recursive file operations like searching, copying, or batch processing.

📋 List Files from a Directory

✅ Basic File Listing

for root, _, files in os.walk("D:\\web"):
    for file in files:
        print(file)

✅ Filter by Extension

html_files = []

for root, _, files in os.walk("D:\\web"):
    for file in files:
        if file.endswith(".html"):
            html_files.append(os.path.join(root, file))

for f in html_files:
    print(f)

🧩 Reusable Function – List Files by Extension

def list_files(path, extensions=None):
    """List files in path. If extensions provided, filter by them."""
    for root, _, files in os.walk(path):
        for file in files:
            if extensions is None:
                yield os.path.join(root, file)
            else:
                for ext in extensions:
                    if file.endswith(ext):
                        yield os.path.join(root, file)

# Usage
for f in list_files(r"D:\web", (".html", ".css")):
    print(f)

🔸 Using a generator (yield) makes this function memory-efficient for large directories.

🧪 Real-World Examples

✅ Example: Backup All .txt Files

import shutil

backup_dir = "D:\\backup"
os.makedirs(backup_dir, exist_ok=True)

for src_file in list_files("D:\\documents", [".txt"]):
    dst_file = os.path.join(backup_dir, os.path.basename(src_file))
    shutil.copy2(src_file, dst_file)
    print(f"Copied {src_file} to {dst_file}")

💡 Hidden Tips & Notes

• 🧩 Use exist_ok=True with os.makedirs() to avoid exceptions if the directory already exists.
• 🧵 Prefer generators over lists for large file sets.
• 📁 Avoid hardcoded paths — always use os.path functions for portability.
• 🚫 os.rmdir() only works on empty directories.
• 📦 Use shutil for advanced operations like copy, move, or remove entire directory trees.
• 🧪 Wrap file/directory operations in try...except blocks to handle permission errors gracefully.

📌 Summary

Task	Code
Get current directory	os.getcwd()
Change directory	os.chdir('new/path')
Join paths	os.path.join('folder', 'file.txt')
Split path	os.path.split(path)
Check if path is dir	os.path.isdir(path)
Create directory	os.mkdir(path)
Create nested directories	os.makedirs(path, exist_ok=True)
Rename directory	os.rename(old, new)
Delete empty directory	os.rmdir(path)
Traverse directory tree	os.walk(path)
List files by extension	Custom function using os.walk() and str.endswith()

🎉 Congratulations! You now have a solid understanding of how to manipulate directories and files in Python, including how to list, create, rename, and delete directories, and how to search and process files recursively.

Next up: 💬 Section 14: Strings – learn about raw strings, escape characters, and how to work with special characters.