1.\" 2.\" Copyright (c) 1993 Paul Kranenburg 3.\" All rights reserved. 4.\" Copyright (c) 2021 The FreeBSD Foundation, Inc. 5.\" 6.\" Portions of this documentation were written by 7.\" Konstantin Belousov <kib@FreeBSD.org> under sponsorship 8.\" from the FreeBSD Foundation. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by Paul Kranenburg. 21.\" 3. The name of the author may not be used to endorse or promote products 22.\" derived from this software without specific prior written permission 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 25.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 28.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34.\" 35.\" $FreeBSD$ 36.\" 37.Dd May 15, 2021 38.Dt LDCONFIG 8 39.Os 40.Sh NAME 41.Nm ldconfig 42.Nd configure the dynamic linker search path for shared libraries 43.Sh SYNOPSIS 44.Nm 45.Op Fl 32 46.Op Fl Rimrv 47.Op Fl f Ar hints_file 48.Op Ar directory | Ar 49.Sh DESCRIPTION 50.Nm 51utility is used to configure the set of paths used by the dynamic linker 52.Xr ld-elf.so.1 1 53when searching for shared libraries. 54The dynamic linker looks for libraries in a set of built-in system directories 55and any directories specified in the hints file. 56This obviates the need for storing search paths within the executable, 57see the 58.Fl rpath 59option for the static linker 60.Xr ld 1 . 61.Pp 62The hints file is maintained by 63.Nm . 64The 65.Ar directories 66list to be stored in the hints file is supplied on the command line. 67.Pp 68Alternatively to the 69.Ar directories 70list on the command line, 71.Ar files 72may be specified; these are expected to contain directories 73to scan for shared libraries. 74Each directory's pathname must start on a new 75line. 76Blank lines and lines starting with the comment character 77.Ql \&# 78are ignored. 79.Pp 80For security reasons, directories which are world or group-writable or which 81are not owned by root produce warning messages and are skipped, unless 82the 83.Fl i 84option is present. 85.Pp 86The 87.Ev LD_LIBRARY_PATH 88environment variable can be used to specify additional 89shared library search directories. 90.Ev LD_LIBRARY_PATH 91is a 92.Sq \&: 93separated list of directory paths which are searched by 94the dynamic linker 95when it needs to load a shared library. 96It can be viewed as the run-time 97equivalent of the 98.Fl L 99switch of 100.Xr ld 1 . 101.Pp 102The following options are recognized by 103.Nm : 104.Bl -tag -width indent 105.It Fl 32 106Generate the hints for 32-bit ABI shared libraries 107on 64-bit systems that support running 32-bit binaries. 108.It Fl elf 109Ignored for backwards compatibility. 110.It Fl R 111Appends pathnames on the command line to the directory list from 112the hints file. 113.Pp 114This is the default action when no options are given. 115.It Fl f Ar hints_file 116Read and/or update the specified hints file, instead of the standard file. 117This option is provided primarily for testing. 118.It Fl i 119Run in insecure mode. 120The security checks will not be performed. 121.It Fl m 122Instead of replacing the list of the directories to search with the 123directories specified on the command line, merge existing list 124with the specified directories, and write the result to the hints file. 125.It Fl r 126List the current list of the directories from the hints file 127on the standard output. 128The hints file is not modified. 129.Pp 130Scan and print all libraries found on the directories list. 131.It Fl v 132Switch on verbose mode. 133.El 134.Sh SECURITY 135Special care must be taken when loading shared libraries into the address 136space of 137.Ev set-user-Id 138programs. 139Whenever such a program is run by any user except the owner of the program, 140the dynamic linker will only load shared libraries from paths found in 141the hints file. 142In particular, the 143.Ev LD_LIBRARY_PATH 144is not used to search for libraries. 145Thus, 146.Nm 147serves to specify the trusted collection of directories from which 148shared objects can be safely loaded. 149.Sh FILES 150.Bl -tag -width /var/run/ld-elf.so.hintsxxx -compact 151.It Pa /var/run/ld-elf.so.hints 152Standard hints file for the ELF dynamic linker. 153.It Pa /etc/ld-elf.so.conf 154Conventional configuration file containing directory names for 155invocations with 156.Fl elf . 157.It Pa /var/run/ld-elf32.so.hints 158Conventional configuration files containing directory names for 159invocations with 160.Fl 32 . 161.El 162.Sh SEE ALSO 163.Xr ld 1 , 164.Xr ld-elf.so.1 , 165.Xr link 5 166.Sh HISTORY 167A 168.Nm 169utility first appeared in SunOS 4.0, it appeared in its current form 170in 171.Fx 1.1 . 172.Pp 173The name 'hints file' is historic from the times when the file also contained 174hints to the dynamic linker. 175This functionality is not provided for ELF. 176