Not any of them!
U mus run the shell scripts with the same name of the *.exe files e.g. icms for icms.exe.
icms is the environment for design entry and simulation.
icfb is for front to back design flow i.e. design entry, simulation, layout, extraction and verification.
look in the document ...install_path/doc/dfIIconfig.pdf at page 11. there is an overview about the several script you can execute and the tools you can use if you start a certain script.
there are very many cadence documents and it is hard to get an overview, but if you have some keydocuments it can help a lot. so i took me time to open each cadence document and made me a short notice of the content and sorted all documents according the importance to me.
Ok i got the idea, the only problem now is that the NCSU has replaced the default parts browser and I cant add components in my designs as the browser only goes down one level (library) where as the orginal goes down 3 levels (library/component type/component). Can I disable the NCSU brower??