How to Append to a File in Python

How to append to a file in Python? Python makes it simple, open the file in append mode, append the data, and close the file. However, In this article, we will learn different methods for appending to a file in Python, including using the write() method, redirecting the output of the print() function to a file, and using a context manager to automatically close the file.

1. Quick Examples of Appending to File

These quick examples will give a high-level overview of different ways to append to a file. We will discuss each method in more detail, later on.


# Quick Examples of Appending to File

# Append to file using the write() method
with open('file.txt', 'a') as f:
    f.write('I am appended text\n')

# Redirect the output of the print() to a file
with open('file.txt', 'a') as f:
    print('I am appended text', file=f)

# Manually closing file
file = open('file.txt', 'a')
file.write('I am appended text\n')
file.close()

2. Append to File in Python

Before appending text to a file, just make sure that the file is available, and that you have the operating system permission for appending the text. If the file is not available, python will create a new file and append the data.

Follow the following 3 steps to append data to a file in Python:

2.1 Step 1: Open the File in Append Mode

To append to a file in Python, you first need to open the file in append mode. You can do it with open() function. When opening the file, you should specify the file name and the mode in which you want to open the file. To open a file in append mode, use the 'a' mode.


# Open file in append mode
file = open("example.txt", "a")

2.2 Step 2: Write to the File

Once you open the file in append mode, you can write to the file using the write() method. This method allows you to write a string to the end of the file.


# Append text to file
file.write("Text to be appended.")

2.3 Step 3: Close the File

After you have finished appending to the file, it is important to close the file using the close() method. This will release any system resources that the file was using.


# Close the file
file.close()

3. Complete Example of Appending Text to a File

This is a complete example of how to append text to a file. As explained above, to append text to a file in Python use the following steps:

Open the file in append mode
Write text to the file
Close the file with close() function


# Open the file in append mode
file = open("example.txt", "a")

# Write to the file
file.write("Text to be appended.")

# Close the file
file.close()

4. Append to File with print() Function

Normally the print() function is used to print text to the console. However, You can also use the print() function to append to a file in Python. To do this, you simply need to specify the file parameter when calling the print() function, which tells Python to redirect the output to the specified file instead of the console.

See the below example:


# Open the file in append mode
file = open("example.txt", "a")

# Write to the file
print('Appended Text', file=file)

# Close the file
file.close()

5. “with” Context Manager

The with statement ensures that the file is closed automatically after the write operation, even if an exception is raised during the write operation. The with statement achieves this by using a context manager, which is a Python object that defines the runtime context for a block of code.


# Using with open()
with open('file.txt', 'a') as f:
    print('Hello, World!', file=f)

When the with statement is used with a file object, it automatically calls the file object’s __enter__() method to set up the context, and then calls the file object’s __exit__() method to tear down the context when the block of code is exited.

6. Example: Append at the Beginning of the File

We can use the seek() function to append at the beginning of the file. By default, the data is appended at the end of the file. The seek() function in Python is used to set the file pointer to a specific position in a file.

Syntax:


# Syntax of seek()
file.seek(offset[, whence])

The offset argument is the number of bytes to move the file pointer. The whence argument specifies the reference point from which to start the offset.

See the below example that helps you to append data at the beginning of the file.


# Open the file in read-write mode
with open('file.txt', 'a') as f:

    # Move the file pointer to the beginning of the file
    f.seek(0)

    # Write the new data to the file
    f.write('New data\n')

See more examples of the seek() function for appending data at different positions.


# Open the file in read-write mode
with open('file.txt', 'r+') as f:
    # Read the first 10 bytes of the file
    f.seek(0)
    data1 = f.read(10)

    # Move the file pointer 5 bytes from the current position
    f.seek(5, 1)

    # Write some data at the new position
    f.write('new data')

    # Move the file pointer to the end of the file
    f.seek(0, 2)

    # Write some more data at the end of the file
    f.write('more data')

7. Summary and Conclusion

In this article, We have learned to append text to a file in Python with multiple approaches. You can append at the end of a file or insert content at a specific position. The seek() function can be used to move the file pointer to a specific position in the file. Hope this article was helpful. Leave questions in the comment section.

Happy Coding!

Frequently Asked Questions on How to Append to a File in Python

How can I open a file in append mode in Python?

You can use the open() function with the mode set to 'a' to open a file in append mode.

What happens if the file doesn’t exist when opening in append mode?

If the file specified in the open() function does not exist, Python will create a new file. Subsequent writes will append content to this newly created file.

Can I append multiple lines at once?

You can append multiple lines at once by using multiple calls to the write() method or the print() function with the file parameter.

How do I ensure that the file is properly closed after appending content?

Using the with statement automatically takes care of closing the file after the indented block. This ensures that resources are released properly.

What if I want to append data to an existing file without creating a new line?

If you want to append content without adding a new line, simply omit the newline character ('\n') from the content you’re writing.