Create a new file and write content to it

In the previous article, we explored how to interact with the operating system using Python—covering fundamental command-line operations and system-level programming. In this article, we’ll dive deeper into file operations in Python, equipping you with efficient techniques for managing and processing files—laying a solid foundation for upcoming debugging practices.

Basic File Operations

File operations typically include creating, reading, writing, deleting, and modifying files. We’ll walk through each of these core operations, illustrated with practical code examples.

Creating a File

In Python, we use the built-in open() function to create files. Its first argument is the filename; the second is the mode. The mode 'w' stands for write, and if the file doesn’t exist, it will be created automatically.

# Create a new file and write content to it
file_path = 'example.txt'

# Open the file (creating it if it doesn’t exist)
with open(file_path, 'w') as file:
    file.write('Hello, World!\n')
    file.write('This is a test file.\n')

Reading a File

Reading a file also uses the open() function—but with mode 'r' (read).

# Read the file content
with open(file_path, 'r') as file:
    content = file.read()
    print(content)

File Writing Modes

Beyond 'w', Python supports several other write-related modes:

• 'a': Append mode — adds content to the end of an existing file (creates the file if it doesn’t exist).
• 'x': Exclusive creation mode — raises an exception if the file already exists.

# Append content to the file
with open(file_path, 'a') as file:
    file.write('Appending a new line to the file.\n')

Deleting a File

To delete a file, use the os module’s remove() function. Ensure the file is closed before deletion.

import os

# Delete the file
os.remove(file_path)

Modifying a File

To modify file content, read it first, make changes in memory, then overwrite or rewrite the file:

# Modify file content
with open(file_path, 'r') as file:
    lines = file.readlines()

lines[0] = 'This line has been modified.\n'

with open(file_path, 'w') as file:
    file.writelines(lines)

Exception Handling in File Operations

File operations often raise exceptions—for example, FileNotFoundError when a file doesn’t exist, or PermissionError due to insufficient access rights. Use try/except blocks to handle them gracefully.

try:
    with open('non_existent_file.txt', 'r') as file:
        content = file.read()
except FileNotFoundError:
    print("File not found. Please check the filename.")
except IOError:
    print("An error occurred while reading the file.")

Advanced Operation: Batch File Processing

In real-world automation, you’ll frequently need to process multiple files. The os module provides utilities like listdir() and path.join() to help iterate over and manage files in bulk.

import os

# Read all files in a specified directory
directory = './my_directory'

for filename in os.listdir(directory):
    if filename.endswith('.txt'):  # Process only .txt files
        file_path = os.path.join(directory, filename)
        with open(file_path, 'r') as file:
            print(f'Content from {filename}:')
            print(file.read())

Summary

In this article, we covered essential file operations in Python—including creating, reading, writing, deleting, and modifying files. Mastering these operations empowers you to manage files flexibly and efficiently, significantly enhancing your automation capabilities. We also emphasized robust exception handling to ensure stability and resilience during file I/O.

Next, we’ll explore practical debugging techniques—equipping you to effectively identify, diagnose, and resolve issues that arise during automation tasks. Through hands-on examples and clear code walkthroughs, you’ll gain confidence applying these concepts right away!