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ldconfig(8)

NAME

     ldconfig -- configure the shared library cache

SYNOPSIS

     ldconfig [-aout | -elf] [-Rimrsv] [-f hints_file] [directory | file ...]

DESCRIPTION

     The ldconfig utility is used to prepare a set of ``hints'' for use by the
     dynamic linker to facilitate quick lookup of shared libraries available
     in multiple directories.  It scans a set of built-in system directories
     and any directories specified on the command line (in the given order)
     looking for shared libraries and stores the results in a system file to
     forestall the overhead that would otherwise result from the directory
     search operations the dynamic linker would have to perform to load the
     required shared libraries.

     Files named on the command line are expected to contain directories to
     scan for shared libraries.  Each directory's pathname must start on a new
     line.  Blank lines and lines starting with the comment character `#' are
     ignored.  Filenames must conform to the lib*.so.[0-9] pattern in order to
     be added to the hints file.

     For security reasons, directories which are world or group-writable or
     which are not owned by root produce warning messages and are skipped,
     unless the -i option is present.

     The shared libraries which are 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 which are
     searched by the dynamic linker when it needs to load a shared library.
     It can be viewed as the run-time equivalent of the -L switch of ld(1).

     The ldconfig utility is typically run as part of the boot sequence.

     The following options are recognized by ldconfig:

     -aout   Generate the hints for a.out format shared libraries.

     -elf    Generate the hints for ELF format shared libraries.

     -R      Rescan the previously configured directories.  This opens the
	     previous hints file and fetches the directory list from the
	     header.  Any additional pathnames on the command line are also
	     processed.  This is the default action when no parameters are
	     given.

     -f hints_file
	     Read and/or update the specified hints file, instead of the stan-
	     dard file.  This option is provided primarily for testing.

     -i      Run in insecure mode.  The security checks will not be performed.


     -s      Do not scan the built-in system directory (``/usr/lib'') for
	     shared libraries.

     -v      Switch on verbose mode.

SECURITY

     Special care must be taken when loading shared libraries into the address
     space of set-user-Id programs.  Whenever such a program is run by any
     user except the owner of the program, the dynamic linker will only load
     shared libraries from the hints file.  In particular, the LD_LIBRARY_PATH
     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.

ENVIRONMENT

     OBJFORMAT	   Overrides /etc/objformat (see below) to determine whether
		   -aout or -elf is the default.  If set, its value should be
		   either `aout' or `elf'.

FILES

     /var/run/ld.so.hints	  Standard hints file for the a.out dynamic
				  linker.
     /var/run/ld-elf.so.hints	  Standard hints file for the ELF dynamic
				  linker.
     /etc/ld.so.conf		  Conventional configuration file containing
				  directory names for invocations with -aout.
     /etc/ld-elf.so.conf	  Conventional configuration file containing
				  directory names for invocations with -elf.
     /etc/objformat		  Determines whether -aout or -elf is the
				  default.  If present, it must consist of a
				  single line containing either
				  `OBJFORMAT=aout' or `OBJFORMAT=elf'.

SEE ALSO

     ld(1), link(5)

HISTORY

     A ldconfig utility first appeared in SunOS 4.0, it appeared in its cur-
     rent form in FreeBSD 1.1.

BUGS

     Some security checks (for example, verifying root ownership of added
     directories) are not performed when -aout is specified.

FreeBSD 5.4			October 3, 1993 		   FreeBSD 5.4

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