awscli iam update角色调用错误,声称缺少必需的参数

This AWS page 建议以下调用:

$ aws iam update-role -–role-name ADFS-Production -–max-session-duration 14400

当我运行这个(替换正确的角色名)时,我得到

aws: error: the following arguments are required: --role-name

这很令人困惑,因为论点就在那里!

$ aws --version

在我的机器上

aws-cli/1.14.69 Python/3.6.4 Darwin/16.3.0 botocore/1.9.22

我尝试使用调试器单步执行arg解析,问题似乎是option\u string\u操作列表没有正确填充:

/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/argparse.py(2093)_parse_optional()
-> if arg_string in self._option_string_actions:
(Pdb) l
2088            # if it doesn't start with a prefix, it was meant to be positional
2089            if not arg_string[0] in self.prefix_chars:
2090                return None
2091    
2092            # if the option string is present in the parser, return the action
2093 ->         if arg_string in self._option_string_actions:
2094                action = self._option_string_actions[arg_string]
2095                return action, arg_string, None
2096    
2097            # if it's just a single character, it was meant to be positional
2098            if len(arg_string) == 1:
(Pdb) self._option_string_actions
{}

但这很复杂,所以很难确定。有什么想法吗?