Improve --help output, set defaults for input files

main.py

@@ -13,27 +13,35 @@ from typing import Any
 def main():
     parser = argparse.ArgumentParser(
         description="Convert a passwd/group/shadow file to a directory of systemd JSON user records.",
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
     )
     parser.add_argument(
-        "passwd_file",
+        "-p",
+        "--passwd_file",
         type=Path,
         help="Path to the passwd file.",
-        metavar="PASSWD_FILE",
+        metavar="PATH",
+        default="/etc/passwd",
     )
     parser.add_argument(
-        "group_file",
+        "-g",
+        "--group_file",
         type=Path,
         help="Path to the group file.",
-        metavar="GROUP_FILE",
+        metavar="PATH",
+        default="/etc/group",
     )
     parser.add_argument(
-        "shadow_file",
+        "-s",
+        "--shadow_file",
         type=Path,
         help="Path to the shadow file.",
-        metavar="SHADOW_FILE",
+        metavar="PATH",
+        default="/etc/shadow",
     )
 
     parser.add_argument(
+        "-o",
         "--output_dir",
         type=Path,
         help="Path to a directory to store json user records.",
@@ -42,22 +50,28 @@ def main():
     )
 
     parser.add_argument(
+        "-e",
         "--email-domain",
         type=str,
+        help="Email domain to construct email addresses for users (i.e. <username>@DOMAIN).",
         required=False,
         metavar="DOMAIN",
     )
 
     parser.add_argument(
+        "-iu",
         "--ignore-user-file",
         type=Path,
+        help="A file containing usernames to ignore (one username per line).",
         required=False,
-        metavar="IGNORE_USER_FILE",
+        metavar="PATH",
     )
 
     parser.add_argument(
+        "-ig",
         "--ignore-group-file",
         type=Path,
+        help="A file containing group names to ignore (one group name per line).",
         required=False,
         metavar="IGNORE_GROUP_FILE",
     )