how to change shared library path

[min yuan]

HI

I recently wrote a c program and compiled it dynamically in order to execute it with adb shell.
So I put the shared library xxx.so into /system/lib, the executable file to /system/bin, then everything works fine.

Now for some reason, I need to put the xxx.so into /system/<custom folder>/lib, the problem comes:  the executable file does not lunch anymore with error message: no such file or directory.

I think it's because the executable file can not find the shared library. So I tried to modify the environment variable LD_LIBRARY_PATH, but it does not work.

Anyone knows where to modify the shared library path?

Thanks in advance,