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

NAME
     ldconfig -- configure the a.out shared library cache

SYNOPSIS
     ldconfig [-cmrsSv]	[directory ...]

DESCRIPTION
     ldconfig is used to prepare a set of "hints" for use by the a.out run-
     time linker ld.so to facilitate quick lookup of shared libraries avail-
     able in multiple directories.  ldconfig is	only available on systems that
     use the "a.out" format for	executables and	libraries - on ELF systems,
     all the work is done by ld.elf_so.

     By	default, it scans a set	of built-in system directories,	directories
     listed in /etc/ld.so.conf,	and any	directories specified on the command
     line (in the given	order) looking for shared libraries and	stores the re-
     sults in the file /var/run/ld.so.hints to forestall 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 di-
	     rectories 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.

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.

SECURITY CONSIDERATIONS
     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 and LD_PRELOAD is	not used to search for li-
     braries.  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 col-
     lection of	directories 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 and LD_PRELOAD from the environ-
     ment.

BSD				October	8, 2000				   BSD

NAME | SYNOPSIS | DESCRIPTION | FILES | SEE ALSO | HISTORY | SECURITY CONSIDERATIONS

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