name : curl_perform_rb.rst perform_rb() -> response_body Perform a file transfer and return response body as a byte string. This method arranges for response body to be saved in a StringIO (Python 2) or BytesIO (Python 3) instance, then invokes :ref:`perform <perform>` to perform the file transfer, then returns the value of the StringIO/BytesIO instance which is a ``str`` instance on Python 2 and ``bytes`` instance on Python 3. Errors during transfer raise ``pycurl.error`` exceptions just like in :ref:`perform <perform>`. Use :ref:`perform_rs <perform_rs>` to retrieve response body as a string (``str`` instance on both Python 2 and 3). Raises ``pycurl.error`` exception upon failure. *Added in version 7.43.0.2.*