strange linking error -- can not find shared library

George2 · 07-10-2006, 05:29 AM

Hello everyone,

I am meeting with a strange linking error when linking with a shared library on Linux platform. I use goo.c to generate libgoo.so, then write an application foo.c and link it with libgoo.so. The error occurs when linking with libgoo.so. The strange point is that, the LD_LIBRARY_PATH is not working, but -L option to gcc works -- I think they should be the same, but in my case below, it seems only -L works.

Here are the source codes,

goo.c

Code:

int goo_export()
{
	return 10;
}

goo.h

Code:

int goo_export();

foo.c

Code:

#include "goo.h"

int main()
{
	goo_export();
}

Error messages,

[root@localhost shared_goo]# gcc -shared goo.c -o libgoo.so
[root@localhost shared_goo]# export LD_LIBRARY_PATH=.
[root@localhost shared_goo]# gcc -I. -lgoo foo.c
/usr/bin/ld: cannot find -lgoo
collect2: ld returned 1 exit status
[root@localhost shared_goo]# gcc -I. -L. -lgoo foo.c

thanks in advance,
George

taylor_venable · 07-10-2006, 11:24 AM

I believe LD_LIBRARY_PATH is for use at execution time, not at linking time. (To determine when to use LD_LIBRARY_PATH, call ldd on the binary. If it can't find a shared lib, you have to set LD_LIBRARY_PATH to tell the kernel where to look.)