ldconfig - configure dynamic linker run-time bindings
/sbin/ldconfig [
-nNvXV] [
-f conf] [
-C
cache] [
-r root]
directory...
/sbin/ldconfig -l [
-v]
library...
/sbin/ldconfig -p
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.
- -c fmt, --format=fmt
- (Since glibc 2.2) Cache format to use: old, new, or
compat (default).
- -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 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.
- /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.
ldd(1),
ld.so(8)