-command_ret_t do_env_print(cmd_tbl_t *, uint_fast8_t, int, char * const []);
-command_ret_t do_env_default(cmd_tbl_t *, uint_fast8_t, int, char * const []);
-command_ret_t do_env_set(cmd_tbl_t *, uint_fast8_t, int, char * const []);
-command_ret_t do_env_save(cmd_tbl_t *, uint_fast8_t, int, char * const []);