ldconfig(8) - phpMan

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 direc-
tory 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, newline, or comma sepa-
rated 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 for-
mat, and is not intended to be edited.
lib*.so.version shared libraries