ldconfig man page on Ubuntu

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ldconfig(8)							   ldconfig(8)

NAME
       ldconfig - configure dynamic linker run-time bindings

SYNOPSIS
       ldconfig [OPTION...]

DESCRIPTION
       ldconfig	 creates,  updates,  and removes the necessary links and cache
       (for use by the run-time linker,	 ld.so)	 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 (/usr/lib  and
       /lib).	ldconfig  checks the header and file names of the libraries it
       encounters when determining which  versions  should  have  their	 links
       updated.	 ldconfig ignores symbolic links when scanning for libraries.

       ldconfig	 will  attempt to deduce the type of ELF libs (ie. libc 5.x or
       libc 6.x (glibc)) based on what C libraries  if	any  the  library  was
       linked  against, therefore when making dynamic libraries, it is wise to
       explicitly link against libc (use -lc).	ldconfig is capable of storing
       multiple	 ABI  types  of libraries into a single cache on architectures
       which allow native running of multiple ABIs, like  ia32/ia64/x86_64  or
       sparc32/sparc64.

       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  like  this
       "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.

       Directory  names	 containing  an = are no longer legal unless they also
       have an expected type specifier.

       ldconfig should normally be run by the super-user  as  it  may  require
       write  permission  on some root owned directories and files. If you use
       -r option to change the root directory, you don't have to be super-user
       though as long as you have sufficient right to that directory tree.

OPTIONS
       -v --verbose
	      Verbose  mode.   Print  current version number, the name of each
	      directory as it is scanned and any links that are created.

       -n     Only process directories specified on the command	 line.	 Don't
	      process  the  trusted  directories (/usr/lib and /lib) nor those
	      specified in /etc/ld.so.conf.  Implies -N.

       -N     Don't rebuild the cache.	Unless -X is also specified, links are
	      still updated.

       -X     Don't  update  links.  Unless -N is also specified, the cache is
	      still rebuilt.

       -f conf
	      Use conf instead of /etc/ld.so.conf.

       -C cache
	      Use cache instead of /etc/ld.so.cache.

       -r root
	      Change to and use root as the root directory.

       -l     Library mode.  Manually link individual libraries.  Intended for
	      use by experts only.

       -p --print-cache
	      Print the lists of directories and candidate libraries stored in
	      the current cache.

       -c --format=FORMAT
	      Use FORMAT for the cache file. Choices are old, new  and	compat
	      (the default).

       -i --ignore-aux-cache
	      Ignore auxiliary cache file.

       -? --help --usage
	      Print usage information.

       -V --version
	      Print version and exit.

EXAMPLES
	      # /sbin/ldconfig -v
       will  set  up the correct links for the shared binaries and rebuild the
       cache.
	      # /sbin/ldconfig -n /lib
       as root after the installation of a new shared  library	will  properly
       update the shared library symbolic links in /lib.

FILES
       /lib/ld-linux.so.*  execution time linker/loader
       /etc/ld.so.conf	   File	 containing  a list of colon, space, tab, new‐
			   line, or comma separated directories	 in  which  to
			   search for libraries.
       /etc/ld.so.cache	   File	 containing an ordered list of libraries found
			   in the directories  specified  in  /etc/ld.so.conf.
			   This	 file  is not in human readable format, and is
			   not intended to be edited.
       lib*.so.version	   shared libraries

SEE ALSO
       ldd(1), ld.so(8).

BUGS
       ldconfig, being a user process, must be run manually and has  no	 means
       of  dynamically	determining  and relinking shared libraries for use by
       ld.so when a new shared library is installed.

AUTHORS
       Andreas Jaeger.	Manual page written by David Engel and Mitch D'Souza.

			       25 February 2008			   ldconfig(8)
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