Is it possible to explain what the magic does? More precisely: what is the difference between an .a and an .so library? -l<libname> links executable with library `lib<libname>' (.so is used by defalt, unless -static is specified in which case .a is used) -L<dir> adds <dir> to library search path default library search path is configured by `ldconfig' utility or /etc/ld.so.sonf, /etc/ld.so.conf.d/* under Linux .a is a static library .so is a dynamic library