man-pages/man8/ldconfig.8

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.\" Copyright 1999 SuSE GmbH Nuernberg, Germany
.\" Author: Thorsten Kukuk <kukuk@suse.de>
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.\" Modified, 6 May 2002, Michael Kerrisk, <mtk-manpages@gmx.net>
.\"   Change listed order of /usr/lib and /lib
.TH LDCONFIG 8 2002-05-06 "GNU C Library" "Linux Programmer's Manual"
.SH NAME
/sbin/ldconfig \- configure dynamic linker run time bindings
.SH SYNOPSIS
.B /sbin/ldconfig
[
.B \-nNvXV
]
[
.BR \-f\ conf
]
[
.BR \-C\ cache
]
[
.BR \-r\ root
]
.IR directory \ ...
.PD 0
.PP
.PD
.BR /sbin/ldconfig
.B \-l
[
.B \-v
]
.IR library \ ...
.PD 0
.PP
.PD
.B /sbin/ldconfig
.B \-p
.SH DESCRIPTION
.B 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
.IR /etc/ld.so.conf ,
and in the trusted directories
.RI ( /lib
and
.IR /usr/lib ).
The cache is used by the run-time linker,
.IR ld.so
or
.IR ld-linux.so .
.B ldconfig
checks the header and file names of the libraries it encounters when
determining which versions should have their links updated.
.PP
.B ldconfig
will attempt to deduce the type of ELF libs (ie. libc5 or libc6/glibc)
based on what C libs, if any, the library was linked against. Therefore, when
making dynamic libraries, it is wise to explicitly link against libc (use -lc).
.PP
Some existing libs do not contain enough information to allow the deduction of
their type. Therefore, the
.IR /etc/ld.so.conf
file format allows the specification of an expected type.  This is
.B only
used for those ELF libs 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
.B not
allowed.  Also see the
.B -p
option.
.B ldconfig
should normally be run by the super-user as it may require write
permission on some root owned directories and files.
.SH OPTIONS
.TP
.B \-v
Verbose mode.
Print current version number, the name of each directory as it
is scanned, and any links that are created.
Overrides quiet mode.
.TP
.B \-n
Only process directories specified on the command line.
Don't process the trusted directories
.RI ( /lib
and
.IR /usr/lib )
nor those specified in
.IR /etc/ld.so.conf .
Implies
.BR \-N .
.TP
.B \-N
Don't rebuild the cache.
Unless
.B \-X
is also specified, links are still updated.
.TP
.B \-X
Don't update links.
Unless
.B \-N
is also specified, the cache is still rebuilt.
.TP
.B \-f conf
Use
.B conf
instead of
.IR /etc/ld.so.conf .
.TP
.B \-C cache
Use
.B cache
instead of
.IR /etc/ld.so.cache .
.TP
.B \-r root
Change to and use
.B root
as the root directory.
.TP
.B \-l
Library mode. Manually link individual libraries. Intended for
use by experts only.
.TP
.B \-p
Print the lists of directories and candidate libraries stored in
the current cache.

.SH FILES
.PD 0
.TP 20
.B /lib/ld.so
run-time linker/loader
.TP 20
.B /etc/ld.so.conf
File containing a list of colon, space, tab, newline, or comma spearated
directories in which to search for libraries.
.TP 20
.B /etc/ld.so.cache
File containing an ordered list of libraries found in the directories
specified in
.BR /etc/ld.so.conf .
.PD