ldconfig creates the necessary links and cache (for use by the run-time linker, ld.so) to the most recent shared libraries found in the direc- tories specified on the command line, in the file /etc/ld.so.conf, and in the trusted directories (/usr/lib and /lib). ldconfig checks the header and file names of the libraries it encounters when determining which versions should have their links updated. ldconfig ignores sym- bolic links when scanning for libraries. ldconfig will attempt to deduce the type of ELF libs (ie. libc 5.x or libc 6.x (glibc)) based on what C libraries if any the library was linked against, therefore when making dynamic libraries, it is wise to explicitly link against libc (use -lc). ldconfig is capable of storing multiple ABI types of libraries into a single cache on architectures which allow native running of multiple ABIs, like ia32/ia64/x86_64 or sparc32/sparc64. lpilinux.com