LDCONFIG(8) Linux Programmer's Manual LDCONFIG(8)
NAME
ldconfig - configure dynamic linker run-time bindings
SYNOPSIS
/sbin/ldconfig [-nNvXV] [-f conf] [-C cache] [-r root] directory...
/sbin/ldconfig -l [-v] library...
/sbin/ldconfig -p
DESCRIPTION
ldconfig creates the necessary links and cache 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, /lib
and /usr/lib (on some 64-bit architectures such as x86-64, /lib and
/usr/lib are the trusted directories for 32-bit libraries, while /lib64
and /usr/lib64 are used for 64-bit libraries).
The cache is used by the run-time linker, ld.so or ld-linux.so. ldcon-
fig checks the header and filenames of the libraries it encounters when
determining which versions should have their links updated.
ldconfig will attempt to deduce the type of ELF libraries (i.e., libc5
or libc6/glibc) based on what C libraries, if any, the library was
linked against.
Some existing libraries 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 used only for
those ELF libraries which we can not work out. The format is
"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. ldconfig should normally be run by the superuser as it may
require write permission on some root owned directories and files.
Note that ldconfig will only look at files that are named lib*.so* (for
regular shared objects) or ld-*.so* (for the dynamic loader itself).
Other files will be ignored. Also, ldconfig expects a certain pattern
to how the symlinks are set up, like this example, where the middle
file (libfoo.so.1 here) is the SONAME for the library:
libfoo.so -> libfoo.so.1 -> libfoo.so.1.12
Failure to follow this pattern may result in compatibility issues after
an upgrade.
OPTIONS
-c fmt, --format=fmt
(Since glibc 2.2) Cache format to use: old, new, or compat.
Since glibc 2.32, the default is new. Before that, it was com-
pat.
-C cache
Use cache instead of /etc/ld.so.cache.
-f conf
Use conf instead of /etc/ld.so.conf.
-i, --ignore-aux-cache
(Since glibc 2.7) Ignore auxiliary cache file.
-l (Since glibc 2.2) Library mode. Manually link individual li-
braries. Intended for use by experts only.
-n Process only the directories specified on the command line.
Don't process the trusted directories, 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.
-p, --print-cache
Print the lists of directories and candidate libraries stored in
the current cache.
-r root
Change to and use root as the root directory.
-v, --verbose
Verbose mode. Print current version number, the name of each
directory as it is scanned, and any links that are created.
Overrides quiet mode.
-V, --version
Print program version.
-X Don't update links. Unless -N is also specified, the cache is
still rebuilt.
FILES
/lib/ld.so
Run-time linker/loader.
/etc/ld.so.conf
File containing a list of directories, one per line, in which to
search for libraries.
/etc/ld.so.cache
File containing an ordered list of libraries found in the direc-
tories specified in /etc/ld.so.conf, as well as those found in
the trusted directories.
SEE ALSO
ldd(1), ld.so(8)
COLOPHON
This page is part of release 5.07 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2020-06-09 LDCONFIG(8)