On MSWindows the mtxrun.lua script is called with mtxrun.exe. On Unix you can either rename mtxrun.lua to mtxrun, or use a symlink. You can create additional stubs, like copy mtxrun.exe luatools.exe copy mtxrun.exe texexec.exe copy mtxrun.exe context.exe copy mtxrun.exe mtx-server.exe The mtxrun.exe program is rather dump and only intercepts mtxrun, luatools and texmfstart (for old times sake) and passes the buck to mtxrun.lua which happens to know enough of mkii to deal with kpse based lookups and therefore acts like texmfstart but when used with mkiv it behaves more clever and looks for more.