This assumes you have already configured the aws command line tool. If not, check out my article on Getting Started with the AWS CLI.

• IAM (Identity and Access Management) Roles contains one or more IAM Policies - Often, a Role will have two Policies.
  • Trust Relationship
  • Permission Policy
• An IAM Policy is JSON that is used to list the principals (users / groups / service accounts) that are allowed or denied to do something (such as listing) on certain resources (such as S3 Buckets).

The aws iam list-users command can be used to list the IAM users that have been created.

~]$ aws iam list-users
{
    "Users": [
        {
            "Path": "/",
            "UserName": "john.doe",
            "UserId": "AIDAABCDL76GLUA6B21234",
            "Arn": "arn:aws:iam::123456789012:user/john.doe",
            "CreateDate": "2022-09-13T11:13:03+00:00"
        }
    ]
}

And here is an example of how to limit the output using the --query option.

aws iam list-users --query 'Users[?UserName==`john.doe`]'