Python - File and Directory Access

File and Directory Access in Python

Python provides extensive capabilities for working with files and directories. These features are essential for reading, writing, modifying files, and navigating directory structures. With built-in modules like os, shutil, and pathlib, Python makes file and directory access both powerful and user-friendly. In this guide, we will explore all the fundamental and advanced operations related to file and directory access in Python.

1. Introduction to File Handling

1.1 What is File Handling?

File handling refers to the process of creating, reading, writing, and deleting files from a filesystem using a programming language. Python makes this process simple using built-in functions and libraries.

1.2 Modes of File Access

• 'r' – Read (default)
• 'w' – Write (overwrites file)
• 'a' – Append (adds to file)
• 'x' – Create (fails if file exists)
• 'b' – Binary mode
• 't' – Text mode (default)

# Example: opening a file for reading
file = open("example.txt", "r")

2. Reading from Files

2.1 Using read() 

with open("example.txt", "r") as file:
    content = file.read()
    print(content)

2.2 Using readline() and readlines()

with open("example.txt", "r") as file:
    line = file.readline()
    print("First Line:", line)

    file.seek(0)  # Go back to start
    lines = file.readlines()
    print("All Lines:", lines)

3. Writing to Files

3.1 Using write()

with open("output.txt", "w") as file:
    file.write("Hello, World!\n")
    file.write("This is Python file writing.")

3.2 Using writelines()

lines = ["Line 1\n", "Line 2\n", "Line 3\n"]
with open("lines.txt", "w") as file:
    file.writelines(lines)

4. Appending to Files

with open("output.txt", "a") as file:
    file.write("\nAppended line.")

5. File Existence and Deletion

5.1 Checking File Existence

import os

if os.path.exists("example.txt"):
    print("File exists.")
else:
    print("File not found.")

5.2 Deleting a File

import os

if os.path.exists("delete_me.txt"):
    os.remove("delete_me.txt")

6. Working with Directories

6.1 Creating Directories

import os

os.mkdir("my_folder")

6.2 Creating Nested Directories

os.makedirs("parent_folder/child_folder")

6.3 Listing Directory Contents

files = os.listdir(".")
print("Current Directory Contents:", files)

6.4 Changing the Working Directory

os.chdir("my_folder")
print("Now in:", os.getcwd())

6.5 Deleting Directories

os.rmdir("my_folder")  # Only works if folder is empty

# For non-empty directories:
import shutil
shutil.rmtree("parent_folder")

7. Path Manipulation

7.1 Using os.path

import os

path = "myfile.txt"
print("Absolute path:", os.path.abspath(path))
print("Exists?", os.path.exists(path))
print("Directory name:", os.path.dirname(path))
print("Base name:", os.path.basename(path))
print("Join path:", os.path.join("folder", "file.txt"))

7.2 Splitting and Getting File Extension

filename = "report.pdf"
name, ext = os.path.splitext(filename)
print("Name:", name)
print("Extension:", ext)

8. Using pathlib for Object-Oriented File Access

8.1 Creating Path Objects

from pathlib import Path

path = Path("example.txt")
print(path.exists())

8.2 Path Operations

from pathlib import Path

file = Path("documents") / "file.txt"
print("Full Path:", file)
print("Parent:", file.parent)
print("Suffix:", file.suffix)

8.3 Reading and Writing

file = Path("data.txt")
file.write_text("Hello with pathlib!")
print(file.read_text())

9. File Handling with Exception Handling

try:
    with open("data.txt", "r") as file:
        content = file.read()
        print(content)
except FileNotFoundError:
    print("File not found.")
except IOError:
    print("Input/output error occurred.")

10. Binary File Access

10.1 Reading and Writing in Binary Mode

with open("image.jpg", "rb") as img_file:
    data = img_file.read()

with open("copy.jpg", "wb") as copy_file:
    copy_file.write(data)

11. File Object Methods and Attributes

11.1 Attributes

• file.name
• file.mode
• file.closed

11.2 Example

with open("sample.txt", "r") as file:
    print("Name:", file.name)
    print("Mode:", file.mode)
    print("Closed?", file.closed)

print("Closed outside context?", file.closed)

12. Context Manager and with Statement

12.1 Benefits of Using with

• Automatically closes file after operation
• Prevents file leaks and resource errors

with open("file.txt", "w") as f:
    f.write("Auto-closed when done.")

13. Temporary Files and Directories

13.1 Using tempfile

import tempfile

with tempfile.NamedTemporaryFile(delete=False) as tmp:
    tmp.write(b"Temporary data")
    print("Temp file path:", tmp.name)

14. Working Recursively with os.walk()

for root, dirs, files in os.walk("."):
    print("Directory:", root)
    for file in files:
        print("File:", file)

Python provides powerful, flexible, and easy-to-use modules for working with files and directories. Whether you are reading or writing text and binary files, navigating file paths, creating and removing directories, or handling exceptions and temporary data, Python has you covered. Modules such as os, shutil, and pathlib form the backbone of file system interaction in Python.

• Use with for safe file operations
• Use os for compatibility with operating systems
• Prefer pathlib for an object-oriented approach
• Always check if files and directories exist before acting

By mastering file and directory access in Python, developers can automate data processing, create configuration and log files, parse datasets, and build robust applications with effective data storage and retrieval mechanisms.