OS Module

Introduction

The OS module provides portable ways to interact with the operating system.

File System Operations

import os

# Paths
os.getcwd()           # Current directory
os.chdir("/path")     # Change directory
os.path.join("a", "b")  # Join paths

# File operations
os.remove("file.txt")
os.rename("old", "new")
os.mkdir("dir")
os.makedirs("a/b/c")  # Create nested dirs
os.rmdir("dir")       # Remove empty dir

# Check existence
os.path.exists("file.txt")
os.path.isfile("file.txt")
os.path.isdir("dir")

Directory Contents

import os

# List directory
os.listdir(".")

# Walk directory tree
for root, dirs, files in os.walk("."):
    print(root, dirs, files)

Environment and Process

import os

# Environment variables
os.environ["HOME"]
os.getenv("PATH")

# Process info
os.getpid()           # Current process ID
os.getuid()           # User ID
os.system("ls")       # Run shell command

Practice Problems

1. Recursively list all files
2. Find files matching pattern
3. Create directory structure
4. Get file metadata
5. Walk directory with filtering