[svlug] modify default directory search order for GCC

[tony yu]

Thanks! Roland,
LD_PRELOAD works! I will look at how i can add -rpath to the gcc option, i
believe it's xlinker
but i have to chcek.

-tony

On 8/8/06, Roland Krause <rokrau at yahoo.com> wrote:
>
> In case you really need a specific version of libz for your
> application, you can always link statically. This has some advantages
> and some obvious disadvantages but it gets rid of your problem.
>
> Another option is to specify -rpath when linking. This adds a directory
> to the runtime library search path. Refer to the manpage for details
> but for quick reference I included the following excerpt:
>
> Begin of man:ld excerpt.
>
> 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.
>
> End of man:ld excerpt.
>
> Additionally you can specify LD_PRELOAD and explicitly load the shared
> library. Example
>
> LD_PRELOAD=/home/you/libz.so myprogram.exe
>
> Further, LD_LIBRARY_PATH has become problematic in recent distributions
> (e.g. FC5), if specified in /etc/profile.d scripts it is overwritten
> somewhere during the startup sequence.
>
> Finally - "Hi Ken, long time no hear :-)"
> Roland
>
>
> --- Fabrizio Bertocci <fabriziobertocci at gmail.com> wrote:
>
> > > i read man ld before, and it does say that LD_LIBRARY_PATH is
> > before /lib
> > > and /usr/lib, however,
> > > if it already has /usr/lib/libz.so from ldd output, it should pick
> > up that
> > > first, am i right?
> > >
> >
> >
> > I think I got the problem: ldd is not just looking at libz.so, but is
> > looking also at a particular library version.
> > So, for the example you sent, at first I only copied libz.so (cp
> > /usr/lib/libz.so .) in my local directory, and after setting
> > LD_LIBRARY_PATH
> > to my local dir, ldd still reported libz from /usr/lib.
> > Then I copied ALL the files (cp -a /usr/lib/libz.so.* .), including
> > the
> > symlinks. After this ldd correctly reported libz from my local dir.
> >
> > Fabrizio
> > > _______________________________________________
> > svlug mailing list
> > svlug at lists.svlug.org
> > http://lists.svlug.org/lists/listinfo/svlug
> >
>
>
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