Question

Im trying to link my program to the shared library. Im using a makefile to compile. It looks like this: `

make: sms_out.cpp SMSDispatch.cpp SMSDispatch.h
      g++ -c -fPIC SMSDispatch.cpp -o SMSDispatch.o
      g++ -shared SMSDispatch.o -o libSMSDispatch.so
`     g++ sms_out.cpp -L. -lSMSDispatch -o sms_out

It works fine if I run the program in the command window with:

LD_LIBRARY_PATH="." ./sms_out

But I want to run it with just ./sms_out, can someone help me?
Tried to add export LD_LIBRARY_PATH=. to the makefile, but that didnt work, just got the error ” error while loading shared libraries: libSMSDispatch.so: cannot open shared object file: No such file or directory” when I try to run the program.

Answer 1

Add the directory where the .so file exists to LD_LIBRARY_PATH:

$ export LD_LIBRARY_PATH=/dir/containing/sharedobject

A utility you may find useful is ldd, which prints the shared library dependencies. For example:

    $ ldd /bin/ls
        linux-vdso.so.1 =>  (0x00007fff819ff000)
        librt.so.1 => /lib64/librt.so.1 (0x00007fc0d3f67000)
        libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fc0d3d4a000)
        libacl.so.1 => /lib64/libacl.so.1 (0x00007fc0d3b42000)
        libc.so.6 => /lib64/libc.so.6 (0x00007fc0d37e9000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fc0d35cd000)
        /lib64/ld-linux-x86-64.so.2 (0x00007fc0d4170000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007fc0d33c9000)
        libattr.so.1 => /lib64/libattr.so.1 (0x00007fc0d31c4000)

If shared objects are not locatable a string not found, or similar, is displayed instead of the path to the shared object being used.