- NetBSD Manual Pages
LDCONFIG(8) NetBSD System Manager's Manual LDCONFIG(8)
Powered by man-cgi (2021-06-01).
Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
ldconfig -- configure the a.out shared library cache
ldconfig [-cmrsSv] [directory ...]
ldconfig is used to prepare a set of ``hints'' for use by the a.out run-
time linker ld.so to facilitate quick lookup of shared libraries avail-
able in multiple directories. ldconfig is only available on systems that
use the ``a.out'' format for executables and libraries - on ELF systems,
all the work is done by ld.elf_so.
By default, it scans a set of built-in system directories, directories
listed in /etc/ld.so.conf, and any directories specified on the command
line (in the given order) looking for shared libraries and stores the
results in the file /var/run/ld.so.hints to forestall the overhead that
would otherwise result from the directory search operations ld.so would
have to perform to load required shared libraries.
The shared libraries so found will be automatically available for loading
if needed by the program being prepared for execution. This obviates the
need for storing search paths within the executable.
The LD_LIBRARY_PATH environment variable can be used to override the use
of directories (or the order thereof) from the cache or to specify addi-
tional directories where shared libraries might be found.
LD_LIBRARY_PATH is a `:' separated list of directory paths that are
searched by ld.so when it needs to load a shared library. It can be
viewed as the run-time equivalent of the -L switch of ld.
ldconfig is typically run as part of the boot sequence.
The following options are recognized by ldconfig:
-c Do not scan directories listed in /etc/ld.so.conf for shared
-m Merge the result of the scan of the directories given as argu-
ments into the existing hints file. The default action is to
build the hints file afresh.
-r Lists the current contents of ld.so.hints on the standard output.
The hints file will not be modified.
-s Do not scan the built-in system directory (/usr/lib), nor any
directories listed in /etc/ld.so.conf for shared libraries.
-S Do not scan the built-in system directory (/usr/lib), for shared
libraries. (Directories listed in /etc/ld.so.conf are still
-v Switch on verbose mode.
ld(1), ld.so(1), ld.so.conf(5), link(5)
A ldconfig utility first appeared in SunOS 4.0, it appeared in its cur-
rent form in NetBSD 0.9A.
Special care must be taken when loading shared libraries into the address
space of set-user-ID programs. Whenever such a program is run, ld.so
will only load shared libraries from the ld.so.hints file. In particu-
lar, the LD_LIBRARY_PATH and LD_PRELOAD is not used to search for
libraries. Thus, the role of ldconfig is dual. In addition to building
a set of hints for quick lookup, it also serves to specify the trusted
collection of directories from which shared objects can be safely loaded.
It is presumed that the set of directories specified to ldconfig is under
control of the system's administrator. ld.so further assists set-user-ID
programs by erasing the LD_LIBRARY_PATH and LD_PRELOAD from the environ-
NetBSD 9.1 October 8, 2000 NetBSD 9.1