Python provides powerful tools for file handling and managing standard output (STDOUT) using the print() function.

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🔹 File Handling in Python

Python allows us to read, write, and manipulate files using the built-in open() function.

📌 Syntax of open()

file = open("filename", mode)

Mode	Description
'r'	Read (default), raises an error if the file doesn’t exist
'w'	Write (creates a new file or overwrites an existing file)
'a'	Append (adds content at the end of the file)
'x'	Create (creates a new file, fails if the file exists)
'b'	Binary mode (e.g., images, videos: 'rb', 'wb')

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🔹 Writing to a File

# Open the file in write mode ('w')
file = open("example.txt", "w")

# Write to the file
file.write("Hello, this is a test file.\n")
file.write("Python file handling is easy!\n")

# Close the file
file.close()

🔹 Note: 'w' mode overwrites the file if it already exists.

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🔹 Reading from a File

file = open("example.txt", "r")  # Open in read mode
content = file.read()  # Read the entire file
print(content)  # Output file content to STDOUT
file.close()

🔹 Alternative Methods to Read:

• read(n): Reads the first n characters.
• readline(): Reads one line at a time.
• readlines(): Reads all lines as a list.

with open("example.txt", "r") as file:
    for line in file:
        print(line.strip())  # Print each line without extra newlines

🔹 Using with open() automatically closes the file after use.

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🔹 Appending to a File

with open("example.txt", "a") as file:
    file.write("This is an additional line.\n")

🔹 Appending does not overwrite existing content.

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🔹 Checking if a File Exists

import os

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

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🔹 Sending Output to STDOUT using print()

By default, print() outputs to Standard Output (STDOUT), which is the console.

print("Hello, World!")  # Output: Hello, World!

📌 Redirecting Output to a File

We can redirect print() output to a file instead of the console.

with open("output.txt", "w") as file:
    print("This will be written to the file.", file=file)

🔹 Now, the message is saved in output.txt instead of printing to the screen.

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🔹 Writing Output to Both STDOUT and a File

import sys

# Open file for writing
file = open("log.txt", "w")

# Print to both STDOUT and file
print("Logging information...", file=file)  # To file
print("Logging information...", file=sys.stdout)  # To STDOUT

file.close()

🔹 sys.stdout ensures output still appears on the screen.

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🔹 Redirecting STDOUT to a File

If you want to redirect all print statements to a file:

import sys

# Open a file for writing
sys.stdout = open("output.log", "w")

print("This message goes to the file, not the console!")
sys.stdout.close()

🔹 After running this, the output will be in output.log instead of the console.

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🎯 Summary

Feature	Example
Write to file	file.write("Hello")
Read from file	file.read()
Append to file	file.write("More content")
Print to STDOUT	print("Hello, World!")
Redirect print() to file	print("Message", file=open("file.txt", "w"))
Redirect all STDOUT to file	sys.stdout = open("log.txt", "w")

Would you like a real-world example, like logging errors to a file? 🚀