Need an Introduction to Tiny Core? Or peruse Core Concepts.
By the way, based on the instructions contained in http://www.rubyrep.org/installation.html, I simply extracted the files and folders from the zip file
By simply isueing the "rubyrep" executable file in the commandline, seemingly the sh command is rather being called.
chmod +x rubyrep
./rubyrep generate myrubyrep.conf