Open Binary File in Append Mode with Python

In Python, to open a binary file in append mode, we can use the open() function with the mode set to ab. This allows us to open an existing file or create a new one. Using the open() function with the appropriate mode enables us to work with the file as needed.

Mode 'ab'

In the mode 'ab', the 'a' stands for append mode, which allows us to add new data to the end of the file without truncating its existing content. The 'b' stands for binary mode, used when handling files containing non-text data or non-readable characters.

Binary files can include a variety of formats, such as image files like GIFs, audio files like MP3s, or binary document formats like Word or PDF.

Syntax to Open a File in 'ab' Mode

Following is the basic basic syntax to open a file in 'ab' mode

with open('filename', 'ab') as file:  
    # Write binary data to the file  
    file.write(b'binary data')

Writing Binary Data in 'ab' Mode

While working with binary data, we have to make sure that our data is in the format of Bytes. We can achieve this by using byte literals. For example, b'\x00\x01\x02\x03' represents a sequence of bytes that can be written to a binary file.

Example

The following example demonstrates how to open a binary file in append mode. Here, the 'with' statement ensures that the file is properly closed after executing its block, even if any exceptions are thrown.

# To open a binary file in append mode 
with open('example.bin', 'ab') as file:
    # Binary Data to append
    data_to_append = b'\x00\x01\x02\x03'
    file.write(data_to_append)

Output

If example.bin was empty before executing the write operation, the output will be:

b'\x00\x01\x02\x03'

Reading Binary Data in 'ab' Mode

When you want to read the contents of a binary file, you should open it in binary read mode. This allows you to retrieve data that isn't in a human-readable format, such as images, audio, or other non-text files.

Example

In this example, we will open a binary file (my_file.mp3) in append mode to potentially add data and then read the entire content from it.

with open('my_file.mp3', 'ab') as f:  
# Now, let's read the content from the same file  
with open('my_file.mp3', 'rb') as f:  
    file_content = f.read()  
    print(file_content)

Output

This output might look something like this (the actual data would be much larger and not interpretable).

b'\xff\xf3\x00\x00\x00\x00\x00\x00\x00\x00...\x00\x00\x00\x00' 

Key Aspects of Append Mode

Some of the Key aspects of append mode are as follows.