# radosgw-admin user create --display-name="master test user" --uid=user1 --email=user1@domain.tld
{
    "user_id": "user1",
    "display_name": "master test user",
    "email": "user1@domain.tld",
    "suspended": 0,
    "max_buckets": 1000,
    "auid": 0,
    "subusers": [],
    "keys": [
        {
            "user": "user1",
            "access_key": "V7C1365TGKF646AVW86Q",
            "secret_key": "8OejnWD3hA5Oks+nOcnLxNbZD2xc78lO++pSUC0r"
        }
    ],
    "swift_keys": [],
    "caps": [],
    "op_mask": "read, write, delete",
    "default_placement": "",
    "placement_tags": [],
    "bucket_quota": {
        "enabled": false,
        "max_size_kb": -1,
        "max_objects": -1
    },
    "user_quota": {
        "enabled": false,
        "max_size_kb": -1,
        "max_objects": -1
    },
    "temp_url_keys": []
}

root@vs69:~# radosgw-admin user create --display-name="master test user" --uid=user2 --email=user1@domain.tld
2015-10-19 08:28:00.856045 7f83f30bd780  0 max_buckets=1000 specified=0
{
    "user_id": "user1",
    "display_name": "master test user",
    "email": "user1@domain.tld",
    "suspended": 0,
    "max_buckets": 1000,
    "auid": 0,
    "subusers": [],
    "keys": [
        {
            "user": "user1",
            "access_key": "V7C1365TGKF646AVW86Q",
            "secret_key": "8OejnWD3hA5Oks+nOcnLxNbZD2xc78lO++pSUC0r"
        }
    ],
    "swift_keys": [],
    "caps": [],
    "op_mask": "read, write, delete",
    "default_placement": "",
    "placement_tags": [],
    "bucket_quota": {
        "enabled": false,
        "max_size_kb": -1,
        "max_objects": -1
    },
    "user_quota": {
        "enabled": false,
        "max_size_kb": -1,
        "max_objects": -1
    },
    "temp_url_keys": []
}

root@vs69:~# radosgw-admin user modify --display-name="master test user" --uid=user2 --email=user2@domain.tld
could not modify user: unable to modify user, user not found