error while loading shared libraries

Question

Thank you guys answering my previous problem on undefined reference to function. As you suggested, the reason under the problem is not linking the libraries. Now I have generated the executable file with: (the version of my g++ and gcc is 4.4.5. I am using Ubuntu 10.10.)

g++ -o ex_addinst  ./ex_addinst.o -L/home/li/work/tools/lindo/lindoapi/bin/linux64 -m64 -llindo64  -lmosek64 -lconsub3 -lc -ldl -lm -lguide -lpthread -lsvml -limf -lirc

But there comes another problem, when I run the executable file with

./ex_addinst

errors appear: (I am not sure I should start a new problem or not currently....)

./ex_addinst: error while loading shared libraries: liblindo64.so.6.0: cannot open shared object file: No such file or directory

But liblindo64.so.6.0 exists in the folder of the lib ~/lindoapi/bin/linux64 which contains following files:

libconsub3.so  libirc.so          liblindojni.so        libmosek64.so.5.0  lindo.par
libguide.so    liblindo64.so      liblindojni.so.6.0.3  libsvml.so         placeholder
libimf.so      liblindo64.so.6.0  libmosek64.so         lindoapivars.sh    runlindo

I have created a symbolic link between liblindo.so.6.0 and liblindo.so:

ln -sf liblindo64.so.6.0 liblindo64.so

There is '-llindo64' is the g++ command, so I thought liblindo64.so.6.0 should have been linked. I have tried to change -L to -Llib, but doesn't help.

Can anyone tell me what is wrong here? Thanks!

Solution 1

You need to have the directory where the .so files live in in runtime linker's search path.

You can do that by changing the LD_LIBRARY_PATH environment variable like this:

export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:$HOME/lindoapi/bin/linux64

before starting your executable.

Solution 2

If you are not going to install libraries currently under /home/li/work/tools/lindo/lindoapi/bin/linux64 into a system directory (/usr/lib, /usr/local/lib, etc.), then it is better to simply link the application such that it will just work(TM):

gcc -o ex_addinst  ./ex_addinst.o \
  -L/home/li/work/tools/lindo/lindoapi/bin/linux64 \
  -Wl,-rpath=/home/li/work/tools/lindo/lindoapi/bin/linux64 \
  -m64 -llindo64  -lmosek64 -lconsub3 -lc -ldl \
  -lm -lguide -lpthread -lsvml -limf -lirc

This is preferable to always having to set LD_LIBRARY_PATH, because

• other people can run your executable (without having to set LD_LIBRARY_PATH) and,
• it doesn't slow down all the other applications (otherwise they will all search LD_LIBRARY_PATH for libc.so.6, etc.)

The reason your LD_LIBRARY_PATH setting didn't work (comment to Mat's answer) is that you used HOME where /home was intended.

Solution 3

to sum the solution:

1. I add the path to ~./bashrc with:

   export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:$HOME/.../lindoapi/bin/linux64

2. (after generating .o file)link the objective file with:

   g++ -o ex_addinst ./ex_addinst.o -L/home/.../lindoapi/bin/linux64 -m64 -llindo64 -lmosek64 -lconsub3 -lc -ldl -lm -lguide -lpthread -lsvml -limf -lirc

Comments

[ulyssis2]

Thanks Mat, in the directionary HOME/.../lindoapi/bin/linux64, there is a lindoapivars.sh file, where the LD_LIBRARY_PATH has been modified as: LD_LIBRARY_PATH=$LD_LIBRARY_PATH:HOME/li/work/tools/lindo/li‌​ndoapi/bin/linux64 export LD_LIBRARY_PATH. But he problem still appears..

[Mat]

Is it HOME or $HOME in that string?

[ulyssis2]

thanks friend, with your suggestion, I added the library into ~/.bashrc: export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/li/work/tools/lindo/l‌​indoapi/bin/linux64, but the problem is still the same. Am I correct to change ~/.bashrc ? I think I am suing non-login shell so I think only ~/.bashrc is read.

[ulyssis2]

it is $HOME, sorry, my typo. As there is the content in lindoapivars.sh, I think this is not the right place to change this variable.

[ulyssis2]

it works now...so queer...I am so happy, thanks for your help! @Mat