Diff between file inside two specified folder

#!/usr/bin/python
# -*- coding: utf-8 -*-

import os
import glob
import optparse
import sys
import pprint


def main():
    # Get the terminal option
    parser = optparse.OptionParser(
        "Using : python compare_filelist.py -a <dir> -b <dir>")
    parser.add_option('-a',
                      dest='dname1',
                      type='string',
                      help='specify folder')
    parser.add_option('-b',
                      dest='dname2',
                      type='string',
                      help='specify folder')
    (options, args) = parser.parse_args()

    if (options.dname1 is None):
        print(parser.usage)
        sys.exit()
    elif (options.dname2 is None):
        print(parser.usage)
        sys.exit()
    else:
        dname1 = options.dname1
        dname2 = options.dname2

    # Get the file list of the given extension in the specified folder
    list1 = glob.glob(os.path.join(dname1, '*.*'))
    list2 = glob.glob(os.path.join(dname2, '*.*'))

    l11 = [os.path.basename(x) for x in list1]
    l22 = [os.path.basename(y) for y in list2]


    # Get the diff between of the list
    list_file_manquants = [f2 for f2 in l22 if f2 not in l11]
    l = str()

    # Return only the file name without the file path
    for file in list_file_manquants:
        try:
            path, filename = os.path.split(file)
            l += filename + '\n'
        except:
            pass

    print(l)

    # Write the file result into a file inside the second specified folder
    with open(os.path.join(dname2, 'fichiers_manquants.txt'), 'w', encoding='utf8') as f:
        f.write(l)

if __name__ == '__main__':
    main()