Linux

Dynamic Shared Objects (DSO)

Ulrich Drepper's How To Write Shared Libraries is a good resource for learning more about the ELF format, about optimizing your shared objects, and how to control the visibility of program symbols in the generated binaries.

C++

Platform detection

To detect whether code is compiled for the Linux platform you can check if __linux__ is defined.

#ifdef __linux__

(here you can find preprocessor definitions for many operating systems)