LDCONFIG(8)               (2020-06-09)                LDCONFIG(8)

     NAME
          ldconfig - configure dynamic linker run-time bindings

     SYNOPSIS
          /sbin/ldconfig [-nNvXV] [-f conf] [ 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. ldconfig 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

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          -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 compat.

          -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 individ-
               ual libraries.  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 directories specified in /etc/ld.so.conf, as well
               as those found in the trusted directories.

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

     COLOPHON
          This page is part of release 5.10 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/.

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