Re: build configuration help

[Bob Rossi]

On Thu, Apr 03, 2008 at 08:55:27AM -0600, John Calcote wrote:
> Bob Rossi wrote:
>> If I put it in the lib directory on other platforms, on startup, how
>> will the binary know where to find the .so? That's why I was asking
>> about LD_LIBRARY_PATH, and creating a script....
>>   
> Okay, let me ask a few questions to clarify your situation. First, is this 
> library being loaded by the linker at runtime, or is it dynamically loaded 
> by your application, using dlopen/dlsym/dlclose (Linux), or 
> LoadLibrary/GetProcAddress/FreeLibrary (Win32)?

I'd like the linker to load it at runtime.

> On Unix systems the "library path" is configured in your application, and 
> in the system. Libraries are searched for (in general) in the system linker 
> cache, which by default contains (at least) "/usr/local/lib:/usr/lib:/lib", 
> as well as others in most cases. If your library is being loaded by the 
> system at app init time, then it should have no trouble finding your 
> library if it's installed in one of these two places. Here's some text I 
> copied (shamelessly) from the ld man page:

Will it only work if I install with the default installation directory? 
What if I change the --prefix=/home/bob/foo. Will /home/bob/foo/bin/bar
be able to find /home/bob/foo/lib/wxwidgets.so ?

>           The linker uses the following search paths to locate required 
> shared libraries.
>
>           1.  Any directories specified by -rpath-link options.
>
>           2.  Any  directories  specified  by -rpath options.  The 
> difference between
>                -rpath and -rpath-link is that directories specified by 
> -rpath options are
>                 included in the executable and used  at  runtime,  whereas 
> the -rpath-link
>                 option is only effective at link time. It is for the native 
> linker only.

OK, I didn't know this. That's awesome. Is this something that I can
count on being portable? Meaning, will it work on all the unix systems
you know about, or is it only a feature of gnu ld?

Thanks for the great help,
Bob Rossi