Section 8: ldconfig
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ldconfig(8) ldconfig(8)
NAME
ldconfig - determine run-time link bindings
SYNOPSIS
ldconfig [-DvqnNX] [-f conf] [-C cache] [-r root]
directory ...
ldconfig -l [-Dvq] library ...
ldconfig -p
DESCRIPTION
ldconfig creates 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 com-
mand 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.
libc5 or libc6/glibc) based on what C libs if any the
library was linked against, therefore when making dynamic
libraries, it is wise to explicitly link against libc (use
-lc).
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 directo-
ries and files. It is normally run automatically at
bootup, from /etc/rc, or manually whenever new DLL's are
installed.
OPTIONS
-D Debug mode. Implies -N and -X.
-v Verbose mode. Print current version number, the
name of each directory as it is scanned and any
links that are created. Overrides quiet mode.
-q Quiet mode. Don't print warnings.
-n Only process directories specified on the command
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ldconfig(8) ldconfig(8)
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 speci-
fied, 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 the lists of directories and candidate
libraries stored in the current cache.
EXAMPLES
In the bootup file /etc/rc having the line
/sbin/ldconfig -v
will set up the correct links for the shared binaries and
rebuild the cache.
On the command line
# /sbin/ldconfig -n /lib
as root after the installation of a new DLL, will properly
update the shared library symbolic links in /lib.
FILES
/lib/ld.so execution time linker/loader
/etc/ld.so.conf File containing a list of colon,
space, tab, newline, or comma
spearated 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.
lib*.so.version shared libraries
SEE ALSO
ldd(1), ld.so(8).
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ldconfig(8) ldconfig(8)
BUGS
ldconfig's functionality, in conjunction with ld.so, is
only available for executables compiled using libc version
4.4.3 or greater.
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 DLL is
installed.
AUTHORS
David Engel and Mitch D'Souza.
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