strncpy(udev_db_filename, udev_config_dir, sizeof(udev_db_filename));
strncat(udev_db_filename, udev_db, sizeof(udev_db_filename));
strncpy(udev_db_filename, udev_config_dir, sizeof(udev_db_filename));
strncat(udev_db_filename, udev_db, sizeof(udev_db_filename));