curl \
  -k \
  -s \
  -H "Accept: application/json" \
  --user caadmin:Secret.123 \
  https://localhost.localdomain:8443/ca/rest/admin/groups | python -m json.tool
{
    "total": 14,
    "entries": [
        {
            "id": "Certificate Manager Agents",
            "GroupID": "Certificate Manager Agents",
            "Description": "Agents for Certificate Manager",
            "Link": {
                "rel": "self",
                "href": "https://localhost.localdomain:8443/ca/rest/admin/groups/Certificate+Manager+Agents",
                "type": "application/xml"
            }
        },
<snip>
    ],
    "Link": []
}