ldconfig(8) - NetBSD Manual Pages

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


NAME

     ldconfig - configure the shared library cache


SYNOPSIS

     ldconfig [-cmrsSv] [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.  By default, it scans a set of built-in system di-
     rectories, directories listed in /etc/ld.so.conf, and any directories
     specified on the command line (in the given order) looking for shared li-
     braries and stores the results in the file /var/run/ld.so.hints to fore-
     stall the overhead that would otherwise result from the directory search
     operations ld.so would have to perform to load 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 that 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:

     -c      Do not scan directories listed in /etc/ld.so.conf for shared li-
             braries.

     -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.

     -r      Lists 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''), nor any
             directories listed in /etc/ld.so.conf for shared libraries.

     -S      Do not scan the built-in system directory (``/usr/lib''), for
             shared libraries.  (Directories listed in /etc/ld.so.conf are
             still scanned.)

     -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 particu-
     lar, 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 direc-
     tories from which shared objects can be safely loaded.  It is presumed
     that the set of directories specified to ldconfig is under control of the
     system's administrator.  ld.so further assists set-user-Id programs by
     erasing the LD_LIBRARY_PATH from the environment.



FILES

     /var/run/ld.so.hints, /etc/ld.so.conf


SEE ALSO

     ld(1),  ld.so(1),  ld.so.conf(5),  link(5)


HISTORY

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

NetBSD                          August 24, 1997                              2