Compile and link (the error appears at link time or runtime depending on -z lazy ):
gcc -Wl,-u,__res_maybe_init@GLIBC_PRIVATE -o test main.c Where main.c is any valid C file. The linker will complain: undefined symbol --res-maybe-init version glibc-private
But for a , use a direct linker undefined reference : Compile and link (the error appears at link
undefined symbol: __res_maybe_init@GLIBC_PRIVATE This is not a real-world fix — it’s a reproduction of the error. The actual fix for such an error (if encountered in real code) is to avoid relying on glibc private symbols and link against the correct public resolver API (e.g., res_ninit , __res_init with appropriate feature test macros). __res_init with appropriate feature test macros).