Backup a file in python

backup.py

'''A simple function to create a backup of a file with a date stamp and backup extension'''
import datetime
import shutil
import os

def create_backup_file(file_name, backup_extension=".bak", date=str(datetime.date.today())):
    '''Create a backup of a file using the given backup extension'''
    backup_file_name = os.path.join(file_name, backup_extension)
    try:
        shutil.copyfile(file_name, backup_file_name)
        os.chmod(backup_file_name, 600)
    except OSError:
        print("Could not create backup file: %s\n", backup_file_name)