This is not possible. When you register a C function in Lua, its visibility is limited to a single interpreter instance obtained with LuaNew(). Different instances are independent and not "know" of each other. One could try to share interpreter instance between processes, but it will crash and burn. The most elegant way is in fact exposing this function as an ARexx command. Alternatively, it foo() may be isolated from defining application, you can place it in a module, which can be later require()-d by any script.

[ Edited by Krashan 26.10.2014 - 09:30 ]