Compare two directory's content size with percentage

compare_directories.py

"""
This is a script to compare the content of two directories.
It was used to determine how complete a series of cp commands were done after the cp process was already started
"""
import os

def directory_size(path):
    total = 0
    for entry in os.scandir(path):
        if entry.is_file():
            total += entry.stat().st_size
        elif entry.is_dir():
            total += directory_size(entry.path)
    return total

if __name__ == '__main__':
    import argparse
    parser = argparse.ArgumentParser(description='Compare the size of two directories')
    parser.add_argument('-f', '--first',
                        required=True,
                        dest='first_directory',
                        help='The first directory to use as the basis for compare')
    parser.add_argument('-s', '--second',
                        required=True,
                        dest='second_directory',
                        help='The second directory to compare to the first')
    args = parser.parse_args()

    first_directory_size = directory_size(os.path.abspath(os.path.expanduser(args.first_directory)))
    second_directory_size = directory_size(os.path.abspath(os.path.expanduser(args.second_directory)))
    percentage_difference = round(100 * (second_directory_size/first_directory_size), 2)
    print('{}({})/{}({}): {}%'.format(args.second_directory, second_directory_size, args.first_directory, first_directory_size, percentage_difference))

Used in combination with the watch command to monitor the progress of cp:

sudo watch -n 1 python3 compare_directories.py -f ./source/ -s /dest/