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NAME    [Toc]    [Back]

     ldconfig - configure the shared library cache

SYNOPSIS    [Toc]    [Back]

     ldconfig [-RUmrsv] [directory ...]

DESCRIPTION    [Toc]    [Back]

     ldconfig is used to prepare a set of ``hints''  for  use  by
the run-time
     linker  ld.so(1)  to  facilitate  quick lookup of shared libraries available
     in multiple directories.  It scans a set of built-in  system
     and  any  directories  specified on the command line (in the
given order)
     looking for shared libraries and stores the results  in  the
     /var/run/ld.so.hints  to  forestall  the overhead that would
otherwise result
 from the directory  search  operations  ld.so(1)  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 additional
 directories where shared libraries might be found.
     LD_LIBRARY_PATH  is  a `:' separated list of directory paths
which are
     searched by ld.so(1) when it needs to load a shared library.
It can be
     viewed as the run-time equivalent of the -L switch of ld(1).

     ldconfig is typically run as part of the boot sequence.   In
addition to
     the  built-in  system  directories,  directories  containing
shared libraries
     may  be   specified   via   the   shlib_dirs   variable   in
/etc/rc.conf.local.  See
     rc.conf(8) for further information.

     The following options are recognized by ldconfig:

     -m      Merge the result of the scan of the directories given as arguments
 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.

     -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

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

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

     -v      Switch on verbose mode.

Security    [Toc]    [Back]

     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(1)
     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  system's  administrator.  ld.so(1) further assists setuser-Id programs
 by erasing the LD_LIBRARY_PATH from the environment.

ENVIRONMENT    [Toc]    [Back]

             Additional directories containing shared  libraries,
settable in
             the user's environment.

             Additional  directories containing shared libraries,
settable in

FILES    [Toc]    [Back]


SEE ALSO    [Toc]    [Back]

     ld(1), link(5), rc.conf(8)

HISTORY    [Toc]    [Back]

     A ldconfig utility first appeared in SunOS 4.0.  It appeared
in its current
 form in NetBSD 0.9a.

OpenBSD      3.6                          October     3,     1993
[ Back ]
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