Can I specify where g++looks for libs at runtime?

[Marc Glisse]

On Mon, 29 Jun 2009, Dr. David Kirkby wrote:

> --with-libiconv-prefix=/usr/lib/iconv

What's that for? Either you use GNU libiconv or you use libc, 
/usr/lib/iconv is just some private libc data.

> I find the C compiler works ok. But the C++ compiler can't find its own 
> library files.

Not the C++ compiler, executables created by said compiler.

> kirkby@t2:[~] $ gcc hello_world.c
> kirkby@t2:[~] $ ./a.out
> hello world
> kirkby@t2:[~] $ g++ test.cpp
> kirkby@t2:[~] $ ./a.out
> ld.so.1: a.out: fatal: libstdc++.so.6: open failed: No such file or directory
> Killed
>
> I'm using the Sun linker, not the GNU one, so it's possible g++ is sending 
> stuff to the linker to indicate where the libraries are, but the linker is 
> ignoring them.
>
> Ideally I'd like to send something to the Sun linker to day "look in 
> /usr/local/gcc-4.4.0-sun-linker/lib for libraries too"

You can use the specs file to change the flags passed by gcc to the 
linker. gcc -dumpspecs shows the default values and truss will show you 
where gcc expects to find a specs file overriding these values. You could 
add some -R/my/path in there (depending on m64/m32), which I think is what 
Sun currently does in Solaris, although it means LD_RUN_PATH will be 
ignored (I think Sun's compiler actually parses this variable to simulate 
its effect, but that's too much work for gcc). You could instead add -c 
my.config to make the program use an alternate ld.config (created with 
crle) which hardcodes a different standard search path for libraries.

-- 
Marc Glisse