Re: Can not link to shared libraries with LD_LIBRARY_PATH.

[Helcio Wagner <hwsilva@xxxxxxxxxxxx>]

   Hi, Ian. Thanks a lot for your help.

   Actually, I don't have neither 'libncx.so' nor 'libagt.so', just 'libncx.so.2.2' and 'libagt.so.2.2'.
 
   The only way to generate the executable was to include the absolute path to those files on gcc command line:

   gcc -Wall test2.c /usr/lib/libncx.so.2.2 /usr/lib/libagt.so.2.2

   Best regards.

---------------------------------------------
HELCIO WAGNER DA SILVA


----- Mensagem original -----
De: Ian Lance Taylor <iant@xxxxxxxxxx>
Para: Helcio Wagner <hwsilva@xxxxxxxxxxxx>
Cc: "gcc-help@xxxxxxxxxxx" <gcc-help@xxxxxxxxxxx>
Enviadas: Sexta-feira, 22 de Junho de 2012 3:06
Assunto: Re: Can not link to shared libraries with LD_LIBRARY_PATH.

Helcio Wagner <hwsilva@xxxxxxxxxxxx> writes:

>    Hi, Ian.
>
>    That's the message received:
>
> helcio@jaguar: gcc -Wall test2.c
> test2.c: Na função ‘main’:
> /tmp/ccab0AHD.o: In function `main':
>
> test2.c:(.text+0xa): undefined reference to `dlq_createQue'
> collect2: ld returned 1 exit status

You didn't use a -l option to tell the linker to search the library
where the symbol is defined.

E.g.,

gcc -Wall test2.c -lncx

Note that for this to work you must have libncx.so or libncx.a in
/usr/lib.  libncx.so.2.2 is used at runtime, not link time.  Packages on
Ubuntu are often split into runtime and development variants; make sure
you have the development package installed.

Ian

> ----- Mensagem original -----
> De: Ian Lance Taylor <iant@xxxxxxxxxx>
> Para: Helcio Wagner <hwsilva@xxxxxxxxxxxx>
> Cc: "gcc-help@xxxxxxxxxxx" <gcc-help@xxxxxxxxxxx>
> Enviadas: Sexta-feira, 22 de Junho de 2012 2:49
> Assunto: Re: Can not link to shared libraries with LD_LIBRARY_PATH.
>
> Helcio Wagner <hwsilva@xxxxxxxxxxxx> writes:
>
>>    I am using gcc 4.6.3 on Ubuntu 12.04. 
>>
>>    First of all, I have no LD_LIBRARY_PATH environment variable set. Should I have it?
>>
>>    Well, I've edited '.bashrc' file to define LD_LIBRARY_PATH and pointed it to '/usr/lib' and '/usr/local/lib' directories:
>>
>> export LD_LIBRARY_PATH=/usr/lib:/usr/local/lib
>
> It is not normally necessary to add these directories to
> LD_LIBRARY_PATH.  See "man ldconfig".
>
>
>>    My executable (named 'test') needs to be linked to two shared libraries to be generated: 'libncx.so.2.2' and 'libagt.so.2.2'. Both are located on '/usr/lib' directory. However, when I type 'gcc -Wall test2.c', there is a message relating undefined references. The executable was not generated.
>
> A problem at link time is most likely not due to LD_LIBRARY_PATH.
>
> When reporting an error message, please cut and paste the exact,
> complete, error output.  Otherwise we don't know what happened.
>
> Ian