Re: Unable to link to library version of my choice

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

On 29 February 2012 08:05, Marc Glisse wrote:
> On Tue, 28 Feb 2012, Marco Ricci wrote:
>
>> I built gtk locally on my computer and the build went fine, but when I
>> wrote a small test program and tried to link it to the library that I built,
>> it compiled fine, but behind the scenes, it actually linked to the file in
>> /usr/lib.
>
>
> I guess you checked that with ldd on your program, not strace on the build?
>
>
>> I've tried everything, -L option, compiling with the full path of the
>> library file and even googling for the answer. I see that others have had
>> the same problem but there are no satisfactory responses. I tried -nostdlib
>> option with gcc but then it started complaining about other libraries.
>
>
> There are 2 operations called linking. One is when you create the binary
> file. Another one is when you run it. -L tells where to look for libraries
> during the first one. -rpath (it is a linker option, so you want -Wl, in
> front) tells where to look during the second one.

As an alternative to using -rpath you can set the LD_LIBRARY_PATH
environment variable so that the executable looks in that path for the
libraries it needs.

gcc -L /foo/bar -lgtk -o prog source.c
./prog  # uses /usr/lib/libgtk.so
export LD_LIBRARY_PATH=/foo/bar
./prog  # uses /foo/bar/libgtk.so

Some people prefer to use -rpath to set the path at link-time, some
prefer to use LD_LIBRARY_PATH to provide the path at run-time.  You
can decide which solution is right for you based on how you want to
use the libraries and the executable.