ldconfig

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  (de-
              fault).

       -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 5.05 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                               2020-02-09                       LDCONFIG(8)