I am using clang on a Mac but I think this question will have the same answer for gcc (and any other unix system -- hopefully).
Right now, I can't link against libboost because it lives in /usr/local/lib. Sure, I can get it to do it with the -L/usr/local/lib and setting LD_LIBRARY_PATH to include /usr/local/lib, but I want my system to search for libraries and includes in /usr/local without the need to specify it in the command line.
Is there a way to do this?
To let your system do this automaticly, you can specify the enviroment variable LIBRARY_PATH (Enviroment Variables) to you library directory (/usr/local/lib).
To make this permanent, just declare this variable in your .bashrc, or similar.
Another way is to change the specs of gcc.
Indeed, this a summary from this question: How to add a default include path for gcc in linux?