LD_LIBRARY_PATH does not work in ld.

It seems man ld(1) says that LD_LIBRARY_PATH is used for search-path of shared libraries. But it seems LD_LIBRARY_PATH does not work in ld.
In fact the explanation in man page doesn't mean like that. If a linked shared library uses another one, LD_LIBRARY_PATH is used. Do not confuse these difference :) "-rpath-link" option can be used for the same purpose. "-rpath-link" has higher priority.

Example

main.c uses libtest1.so
libtest1.so uses libtest2.so

1. In case there is dependency from libtest1 to libtest2.



$ gcc -shared -fPIC test2.c -o libtest2.so

$ gcc -shared -fPIC test1.c -o libtest1.so -ltest2 -L.

$ ldd libtest1.so

        linux-vdso.so.1 =>  (0x00007fff4bfff000)

        libtest2.so => /home/user/hoge/libtest2.so (0x00007f96de0f3000)

        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f96ddd42000)

        /lib64/ld-linux-x86-64.so.2 (0x00007f96de4f9000)

$ gcc -c main.c -o main.o

$ gcc main.o -ltest1 -L .

/usr/bin/ld: warning: libtest2.so, needed by /home/user/hoge/libtest1.so, not found (try using -rpath or -rpath-link)

/home/user/hoge/libtest1.so: undefined reference to `func_in_litest2'

$ export LD_LIBRARY_PATH=`pwd`

$ gcc main.o -ltest1 -L .

$

2. In case there is no dependency information written in libtest1.so. It is required to specify -ltest2 explicitly.



$ gcc -shared -fPIC test2.c -o libtest2.so

$ gcc -shared -fPIC test1.c -o libtest1.so

$ ldd libtest1.so

        linux-vdso.so.1 =>  (0x00007fff4bfff000)

        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f96ddd42000)

        /lib64/ld-linux-x86-64.so.2 (0x00007f96de4f9000)

$ gcc -c main.c -o main.o

$ export LD_LIBRARY_PATH=`pwd`

$ gcc main.o -ltest1 -L .

./libtest1.so: undefined reference to `func_in_libtest2'

$ gcc main.o -ltest1 -ltest2 -L.

$

When gcc is used for link, LIBRARY_PATH (not LD_LIBRARY_PATH) can be used instead of "-L" option.



$ gcc -shared -fPIC test.c -o libtest.so

$ export LIBRARY_PATH=`pwd`

$ gcc main.c -ltest