Linux runtime linker error - c++

Question

I'm working though the First Steps tutorial on the POCO Project site, and I've successfully built the library (Debian Linux, 2.6.26, gcc 4.3.2) under my home directory
~/Development/POCO
with the shared libraries located in
~/Development/POCO/lib/Linux/x86_64/lib
My problem is that any application I build that depends on these libraries can only be run from the shared library directory.
~/Development/POCO/lib/Linux/x86_64$ ldd ~/Development/Cloud/DateTimeSample/bin/Linux/x86_64/DateTime
linux-vdso.so.1 => (0x00007fffe69fe000)
libPocoFoundation.so.6 (0x00007fa8de44f000)
libpthread.so.0 => /lib/libpthread.so.0 (0x00007fa8de233000)
libdl.so.2 => /lib/libdl.so.2 (0x00007fa8de02f000)
librt.so.1 => /lib/librt.so.1 (0x00007fa8dde26000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007fa8ddb1a000)
libm.so.6 => /lib/libm.so.6 (0x00007fa8dd897000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00007fa8dd680000)
libc.so.6 => /lib/libc.so.6 (0x00007fa8dd32d000)
/lib64/ld-linux-x86-64.so.2 (0x00007fa8de7e0000)
And running DateTime from this directory would work as you would expect. However
~/Development/Cloud/DateTimeSample/bin/Linux/x86_64$ ldd DateTime
linux-vdso.so.1 => (0x00007fff24dfe000)
libPocoFoundation.so.6 => not found
libpthread.so.0 => /lib/libpthread.so.0 (0x00007ffc1c7dd000)
libdl.so.2 => /lib/libdl.so.2 (0x00007ffc1c5d9000)
librt.so.1 => /lib/librt.so.1 (0x00007ffc1c3d0000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007ffc1c0c4000)
libm.so.6 => /lib/libm.so.6 (0x00007ffc1be41000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00007ffc1bc2a000)
libc.so.6 => /lib/libc.so.6 (0x00007ffc1b8d7000)
/lib64/ld-linux-x86-64.so.2 (0x00007ffc1c9f9000)
so running the executable from any other directory results in
error while loading shared libraries: libPocoFoundation.so.6: cannot open shared object file: No such file or directory
Looking at the output from the make process, the directory is correctly specified
g++ [blah] -L/home/npalko/Development/POCO/lib/Linux/x86_64
-lPocoFoundation
I've tried setting LD_LIBRARY_PATH to /home/npalko/Development/POCO/lib/Linux/x86_64, but it has not changed anything. Any help would be greatly appreciated!

Answer 1

If you don't want to have to deal with the LD_LIBRARY_PATH variable, you can add the linker -rpath option to the gcc command line. In your case, this would be:
gcc ... -Wl,-rpath=/home/npalko/Development/POCO/lib/Linux/x86_64
This effectively hardcodes that path in the executable, so it may or may not be suitable for your purposes.

Answer 2

This fails?
LD_LIBRARY_PATH=/home/npalko/Development/POCO/lib/Linux/x86_64 ~/Development/Cloud/DateTimeSample/bin/Linux/x86_64/DateTime
Just thought you may not be setting LD_LIBRARY_PATH properly
And this?
ls -alh /home/npalko/Development/POCO/lib/Linux/x86_64/libPocoFoundation.so
If both fail I can't see a reason.

Answer 3

You must specify to the linker the path of your library
g++ [blah] -Wl,-rpath=/home/npalko/Development/POCO/lib/Linux/x86_64
-Wl means your pass an option to the linker
-rpath is the linker option
Add a directory to the runtime library search path. This is used
when linking an ELF executable with shared objects. All -rpath
arguments are concatenated and passed to the runtime linker, which
uses them to locate shared objects at runtime. The -rpath option
is also used when locating shared objects which are needed by
shared objects explicitly included in the link;