The magical command
sudo /sbin/ldconfig -v reconfigures/indexes the files you installed into the lib.
For example, if you see errors such as:
~/w/h/build (master) > curse curse: error while loading shared libraries: libhexer.so.1.1.0: cannot open shared object file: No such file or directory
~/w/e/build (master)> entwine entwine: error while loading shared libraries: libentwine.so.2: cannot open shared object file: No such file or directory
Then go and run the magical command.
Typically this is needed when you do
sudo make install after compiling some C++ code. I suppose you don't need the
-v verbose flag, because
ldconfig - configure dynamic linker run-time bindings.