1.\" 2.\" Copyright (c) 1993 Paul Kranenburg 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. All advertising materials mentioning features or use of this software 14.\" must display the following acknowledgement: 15.\" This product includes software developed by Paul Kranenburg. 16.\" 3. The name of the author may not be used to endorse or promote products 17.\" derived from this software without specific prior written permission 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29.\" 30.\" $FreeBSD: src/sbin/ldconfig/ldconfig.8,v 1.19.2.10 2003/05/13 19:25:19 trhodes Exp $ 31.\" 32.Dd October 3, 1993 33.Dt LDCONFIG 8 34.Os 35.Sh NAME 36.Nm ldconfig 37.Nd configure the shared library cache 38.Sh SYNOPSIS 39.Nm 40.Op Fl elf 41.Op Fl Rimr 42.Op Fl f Ar hints_file 43.Op Ar directory | Ar 44.Sh DESCRIPTION 45The 46.Nm 47utility is used to prepare a set of 48.Dq hints 49for use by the dynamic linker 50to facilitate quick lookup of shared libraries available in multiple 51directories. It scans a set of built-in system directories and any 52.Ar directories 53specified on the command line (in the given order) looking for 54shared libraries and stores the results in a system file to forestall 55the overhead that would otherwise result from the directory search 56operations the dynamic linker would have to perform to load the 57required shared libraries. 58.Pp 59Files named on the command line are expected to contain directories 60to scan for shared libraries. Each directory's pathname must start on a new 61line. Blank lines and lines starting with the comment character 62.Ql \&# 63are ignored. 64Filenames must conform to the 65.Pa lib*.so.[0-9] 66pattern in order to be added to the hints file. 67.Pp 68For security reasons, directories which are world or group-writable or which 69are not owned by root produce warning messages and are skipped, unless 70the 71.Fl i 72option is present. 73.Pp 74The shared libraries which are found will be automatically available for loading 75if needed by the program being prepared for execution. 76This obviates the need 77for storing search paths within the executable. 78.Pp 79The 80.Ev LD_LIBRARY_PATH 81environment variable can be used to override the use of 82directories (or the order thereof) from the cache or to specify additional 83directories where shared libraries might be found. 84.Ev LD_LIBRARY_PATH 85is a 86.Sq \&: 87separated list of directory paths which are searched by 88the dynamic linker 89when it needs to load a shared library. 90It can be viewed as the run-time 91equivalent of the 92.Fl L 93switch of 94.Xr ld 1 . 95.Pp 96The 97.Nm 98utility is typically run as part of the boot sequence. 99.Pp 100The following options are recognized by 101.Nm : 102.Bl -tag -width indent 103.It Fl elf 104Generate the hints for ELF format shared libraries. 105.It Fl R 106Rescan the previously configured directories. This opens the previous hints 107file and fetches the directory list from the header. Any additional pathnames 108on the command line are also processed. 109This is the default action when no parameters are given. 110.It Fl f Ar hints_file 111Read and/or update the specified hints file, instead of the standard file. 112This option is provided primarily for testing. 113.It Fl i 114Run in insecure mode. The security checks will not be performed. 115.It Fl m 116Instead of replacing the contents of the hints file 117with those found in the directories specified, 118.Dq merge 119in new entries. 120Directories recorded in the hints file by previous runs of 121.Nm 122are also rescanned for new shared libraries. 123.It Fl r 124List the current contents of the hints file 125on the standard output. 126The hints file is not modified. The list of 127directories stored in the hints file is included. 128.\".It Fl s 129.\"Do not scan the built-in system directory 130.\".Pq Dq /usr/lib 131.\"for shared libraries. 132.El 133.Sh SECURITY 134Special care must be taken when loading shared libraries into the address 135space of 136.Ev set-user-Id 137programs. 138Whenever such a program is run by any user except the owner of the program, 139the dynamic linker 140will only load shared libraries from the hints 141file. 142In particular, the 143.Ev LD_LIBRARY_PATH 144is not used to search for libraries. 145Thus, the role of 146.Nm 147is dual. 148In addition to building a set of hints for quick lookup, it also serves to 149specify the trusted collection of directories from which shared objects can 150be safely loaded. 151.Sh FILES 152.Bl -tag -width /var/run/ld-elf.so.hintsxxx -compact 153.It Pa /var/run/ld-elf.so.hints 154Standard hints file for the ELF dynamic linker. 155.It Pa /etc/ld-elf.so.conf 156Conventional configuration file containing directory names for 157invocations with 158.Fl elf . 159.El 160.Sh SEE ALSO 161.Xr ld 1 , 162.Xr link 5 163.Sh HISTORY 164A 165.Nm 166utility first appeared in SunOS 4.0, it appeared in its current form 167in 168.Fx 1.1 . 169