unistd.h's chdir gives undefined reference to symbol 'chdir@@GLIBC_2.2.5' on linux

Question

When linking some object files together using ld, an error occurs:

undefined reference to symbol 'chdir@@GLIBC_2.2.5'

undefined reference to symbol 'setlocale@@GLIBC_2.2.5'

Do I need to link a library for this function? The manpage does not say anything about linking.

Answer 1

C and C++ share a notion of what a standard library is: it is a bunch of libraries that are always available in the C (or C++) build tool.

The problem is that ld is a far more generic tool: it can be used to link C, C++, Fortran, assembly language, etc. The compilers know how to pass specific options to the loader to ask it to find the relevant libraries, but when you directly use ld, you have to pass them explicitely.

Alternatively, avoid using ld and always use c++ (or g++ or whatever name your compiler is called) even for simply linking.