how to render file sequence using file-output without composite node.

Hi, how can i set frame range to render inside the compositing ? I can only set the range in the global ‘render’ tab , but this only works if also set the output path in this render tab. If i don’t set the path (make it empty , because i don’t want to render final comp, i just want to render out some intermmediate render using file output nodes ) , then the frame range has no effect. it only render the first frame , even if i use ‘render animation’ . is something broken ?