--- a/m209/main.py	Sun Jun 09 14:18:24 2013 -0500
+++ b/m209/main.py	Tue Jun 11 19:53:07 2013 -0500
@@ -0,0 +1,63 @@
+# Copyright (C) 2013 by Brian Neal.
+# This file is part of m209, the M-209 simulation.
+# m209 is released under the MIT License (see LICENSE.txt).
+
+"""This module contains the main() entry point for the command-line m209
+utility.
+
+"""
+import argparse
+
+
+DESC = "M-209 simulator and utility program"
+DEFAULT_KEY_LIST = 'm209keys.cfg'
+
+
+def encrypt(args):
+    """Encrypt subcommand processor"""
+    print('Encrypting!', args)
+
+
+def decrypt(args):
+    """Decrypt subcommand processor"""
+    print('Decrypting!', args)
+
+
+def main(argv=None):
+    """Entry point for the m209 command-line utility."""
+
+    # create the top-level parser
+    parser = argparse.ArgumentParser(description=DESC)
+    subparsers = parser.add_subparsers(title='list of commands',
+        description='type %(prog)s {command} -h for help on {command}')
+
+    # create the parser for encrypt
+    enc_parser = subparsers.add_parser('encrypt', aliases=['en'],
+        help='encrypt text')
+    enc_parser.add_argument('-k', '--keylist', default=DEFAULT_KEY_LIST,
+        help='path to key list file [default: %(default)s]')
+    enc_parser.add_argument('-i', '--keylist-indicator',
+        help='2 letter key list indicator')
+    enc_parser.add_argument('-p', '--plaintext',
+        help='plaintext string to encrypt; prompted if omitted')
+    enc_parser.add_argument('-e', '--ext-msg-ind',
+        help='6 letter external message indicator; if omitted a random one is used')
+    enc_parser.add_argument('-s', '--sys-ind',
+        help='1 letter system indicator; if omitted a random one is used')
+    enc_parser.set_defaults(subcommand=encrypt)
+
+    # create the parser for decrypt
+    enc_parser = subparsers.add_parser('decrypt', aliases=['de'],
+        help='decrypt text')
+    enc_parser.add_argument('-k', '--keylist', default=DEFAULT_KEY_LIST,
+        help='path to key list file [default: %(default)s]')
+    enc_parser.add_argument('-c', '--ciphertext',
+        help='ciphertext string to decrypt; prompted if omitted')
+    enc_parser.set_defaults(subcommand=decrypt)
+
+    args = parser.parse_args(args=argv)
+    args.subcommand(args)
+
+
+if __name__ == '__main__':
+    main()