LDCONFIG(8)             OpenBSD System Manager's Manual            LDCONFIG(8)

NAME
     ldconfig - configure the shared library cache

SYNOPSIS
     ldconfig [-RUmrsv] [directory ...]

DESCRIPTION
     ldconfig is used to prepare a set of ``hints'' for use by the run-time
     linker ld.so to facilitate quick lookup of shared libraries available in
     multiple directories. It scans a set of built-in system directories and
     any directories specified on the command line (in the given order) look-
     ing for shared libraries and stores the results in the file
     /var/run/ld.so.hints to forestall the overhead that would otherwise re-
     sult from the directory search operations ld.so would have to perform to
     load the required shared libraries.

     The shared libraries so found will be automatically available for loading
     if needed by the program being prepared for execution. This obviates the
     need for storing search paths within the executable.

     The LD_LIBRARY_PATH environment variable can be used to override the use
     of directories (or the order thereof) from the cache or to specify addi-
     tional directories where shared libraries might be found.
     LD_LIBRARY_PATH is a `:' separated list of directory paths which are
     searched by ld.so when it needs to load a shared library. It can be
     viewed as the run-time equivalent of the -L switch of ld.

     ldconfig is typically run as part of the boot sequence.

     The following options are recognized by ldconfig:

     -R      Rescan the previously configured directories. This opens the
             hints file and fetches the directory list from the header. Any
             additional pathnames on the command line are also processed.

     -U      Unconfigure directories specified on the command line or remove
             inaccessible directories from search path if no directories spec-
             ified. This option cannot be used with -m.

     -m      Merge the result of the scan of the directories given as argu-
             ments into the existing hints file. The default action is to
             build the hints file afresh. This option cannot be used with -U.

     -r      List the current contents of ld.so.hints on the standard output.
             The hints file will not be modified.

     -s      Do not scan the built-in system directory (``/usr/lib'') for
             shared libraries.

     -v      Switch on verbose mode.

Security
     Special care must be taken when loading shared libraries into the address
     space of set-user-Id programs. Whenever such a program is run, ld.so will
     only load shared libraries from the ld.so.hints file. In particular, the
     LD_LIBRARY_PATH is not used to search for libraries. Thus, the role of
     ldconfig is dual.  In addition to building a set of hints for quick
     lookup, it also serves to specify the trusted collection of directories
     from which shared objects can be safely loaded. It is presumed that the
     set of directories specified to ldconfig are under control of the sys-
     tem's administrator.  ld.so further assists set-user-Id programs by eras-
     ing the LD_LIBRARY_PATH from the environment.


FILES
     /var/run/ld.so.hints

SEE ALSO
     ld(1), link(5)

HISTORY
     A ldconfig utility first appeared in SunOS 4.0, it appeared in its cur-
     rent form in NetBSD 0.9a.

OpenBSD 3.0                     October 3, 1993                              2
