./app: error while loading shared libraries: libfg.so: cannot open shared object file

x_gaurav · 06-27-2009, 02:10 AM

Hi,

I am using Ubuntu 8.10
I wrote a simple program using shared library. this is what I did.

gcc -c -fPIC s1.c
gcc -c -fPIC s2.c
gcc -shared -fPIC -o libfg.so s1.o s2.o
gcc -c app.c
gcc -o app app.o -L. -lfg
./app

Ouput

./app: error while loading shared libraries: libfg.so: cannot open shared object file: Error 40

Why am I getting this error? What is error 40?
The program works if i make libfg a static library instead of a shared one.

fpmurphy · 06-27-2009, 08:39 AM

Have you told the loader where to find the shared library using LD_LIBRARY_PATH?

Alternatively you could use ld's rpath option, which specifies the runtime library search path of that particular program being compiled. In gcc, you can configure the rpath option by specifying it this way:

Code:

 -Wl,-rpath,$(DEFAULT_LIB_INSTALL_PATH)

x_gaurav · 06-27-2009, 12:32 PM

Thanks. This worked. just a simple question though. The shared library libfg.so was in a local directory. When trying earlier i had made symbolic links to it in /lib,/usr/lib and /usr/local/lib.

Shouldn't that have worked earlier? can't the Loader simply follow the symbolic links.