ldconfig creates the necessary links and cache to the most recent shared
libraries found in the directories specified on the command line, in the file
/etc/ld.so.conf, and in the trusted directories (/lib and
/usr/lib). The cache is used by the run-time linker, ld.so or
ld-linux.so. ldconfig checks the header and file names of the
libraries it encounters when determining which versions should have their
ldconfig will attempt to deduce the type of ELF libs (ie. libc5 or
libc6/glibc) based on what C libs, if any, the library was linked against.
Therefore, when making dynamic libraries, it is wise to explicitly link
against libc (use -lc).
Some existing libs do not contain enough information to allow the deduction of
their type. Therefore, the /etc/ld.so.conf file format allows the
specification of an expected type. This is only used for those ELF libs
which we can not work out. The format is "dirname=TYPE", where TYPE
can be libc4, libc5, or libc6. (This syntax also works on the command line.)
Spaces are not allowed. Also see the -p option. ldconfig
should normally be run by the super-user as it may require write permission on
some root owned directories and files.