Because rayshade provides a default camera description, surface properties, and a default light source, it is easy to construct short input files that allow you to experiment with objects, textures, and transformations. If you haven't already run rayshade on one of the example input files, you might want to try producing an image using the following input:
sphere 2 0 0 0
If you are running rayshade on a UNIX-like machine, the command:
echo "sphere 2 0 0 0" | rayshade > sphere.rleshould produce an image of a sphere.