undefined reference to symbol even when nm indicates that this symbol is present in the shared library

Question

What could be wrong here? I have the following simple class: ``` #include "libmnl/libmnl.h" int main() { struct mnl_socket *a = mnl_socket_open(12); } ``` And after running a simple `gcc` compile (`gcc -lmnl main.c`) I get the following errors: ``` /tmp/cch3GjuS.o: In function `main': main.c:(.text+0xe): undefined reference to `mnl_socket_open' collect2: ld returned 1 exit status ``` Running nm on the shared library shows that it's actually found: ``` aatteka@aatteka-Dell1:/tmp$ nm -D /usr/lib/libmnl.so | grep mnl_socket_open 0000000000001810 T mnl_socket_open ``` This is happening on Ubuntu 12.04. The libmnl-dev and libmnl0 packages are installed. The `strace` output of `gcc` indicates that `ld` is using exactly that *.so file: ``` [pid 10988] stat("/usr/lib/gcc/x86_64-linux-gnu/4.6/libmnl.so", 0x7fff2a39b470) = -1 ENOENT (No such file or directory) [pid 10988] open("/usr/lib/gcc/x86_64-linux-gnu/4.6/libmnl.so", O_RDONLY) = -1 ENOENT (No such file or directory) [pid 10988] stat("/usr…

Accepted Answer

Libraries must be listed after the objects that use them (more precisely, a library will be used only if it contains a symbol that satisfies an undefined reference known at the time it is encountered). Move the `-lmnl` to the end of the command.

undefined reference to symbol even when nm indicates that this symbol is present in the shared library

Solution

Problem