Using python script find different pattern file from a directory and replace file name as a way we want.

file_process.py

import re
import glob, os


def file_rename(dir, pattern, titlePattern):
    for pathAndFilename in glob.iglob(os.path.join(dir, pattern)):
        title, ext = os.path.splitext(os.path.basename(pathAndFilename))
        replace_file = re.sub("[^a-zA-Z0-9_]+", "_", title)
        new_filename = (replace_file + ext ).lower()
        os.rename(pathAndFilename,
                  os.path.join(dir, titlePattern + new_filename))
                  # os.path.join(dir, new_filename))


if __name__ == '__main__':
    file_rename("/home/giasuddin/Downloads/dir_name", "*.pdf", "file_")