I created a curve with curve sop. Then I generated a rib file. But the curve command does not exist in that rib file. Can any one tell me why?
How can I use renderman to render curves by using Houdini?

Three things.

Make sure the curve is a polygon.
Make sure it has a width attribute.
By default the curve will render as linear. If you want a smooth curve change the “RiCurve Basis” type to “cubic” in the “Specific Tab” of the RenderMan Rop.

jim.