Check If A File is Writable in Python

When it comes to Python programming it is essential to work with files. One important aspect is making sure that a file can be written before you try to make any changes. In this article, we will see how we can check if a file is writable in Python.

Check If a File Is Writable in Python

Below are some of the ways by which we can check if a file is writable in Python:

• Using os.access() Function
• Verifying Writability
• Using the file object’s writable() method

Using the os.access() Function

This method is more useful to check if the given file is writable, and whether the matter file exists or not. It uses the os.access() function that inquires about the permissions of the specified file, from the operating system.

Python3

import os

# Replace with the actual file path
file_path = "C:/Users/Pankaj Kumar Bind/Downloads/Test.txt"

try:
    # Check if the file is writable using os.access()
    if os.access(file_path, os.W_OK):
        print(f"File '{file_path}' is writable.")
    else:
        print(f"File '{file_path}' is not writable.")

except FileNotFoundError:
    print(f"File '{file_path}' does not exist.")
except PermissionError:
    print(f"You don't have permission to access or write to '{file_path}'.")

Output:

Verifying Writability

This approach follows Python conventions and this is more succinct especially when working with existing files. It tries to open the file in mode (“w”) and verifies if a PermissionError exception occurs.

Python3

import os

# Replace with the actual file path
filepath = "C:/Users/Pankaj Kumar Bind/Desktop/test.txt"

def isFileWritable(filepath):
    """Checks if a file is writable by attempting to open it in write mode.

    Args:
        filepath (str): The path to the file.

    Returns:
        bool: True if the file is writable, False otherwise.
    """

    try:
        with open(filepath, "w") as f:
            # Write something to verify writability
            f.write("Test")
            return True
    except PermissionError:
        return False

if isFileWritable(filepath):
    print(f"{filepath} is writable.")
else:
    print(f"{filepath} is not writable.")

Output:

Using writable() Method

This method is the most efficient approach if you’ve already opened the file in write mode (“w”). To determine if a file is writable it simply invokes the writable() method, on the file object.

Python3

def isFileWritable(file_object):
    """Checks if an already opened file is writable.

    Args:
        file_object: The opened file object.

    Returns:
        bool: True if the file is writable, False otherwise.
    """

    return file_object.writable()

# Provide the file path here
filepath = "example3.py"

# Open the file in write mode
with open(filepath, "w") as f:
    # Check if the opened file is writable
    if isFileWritable(f):
        print(f"The file {filepath} is writable.")
    else:
        print(f"The file {filepath} is not writable.")

Output: