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.\" $FreeBSD$ 31.\" 32.Dd December 31, 2020 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 32 41.Op Fl elf 42.Op Fl Rimrsv 43.Op Fl f Ar hints_file 44.Op Ar directory | Ar 45.Sh DESCRIPTION 46The 47.Nm 48utility is used to prepare a set of 49.Dq hints 50for use by the dynamic linker 51to facilitate quick lookup of shared libraries available in multiple 52directories. 53It scans a set of built-in system directories and any 54.Ar directories 55specified on the command line (in the given order) looking for 56shared libraries and stores the results in a system file to forestall 57the overhead that would otherwise result from the directory search 58operations the dynamic linker would have to perform to load the 59required shared libraries. 60.Pp 61Alternatively, 62.Ar files 63may be specified; these are expected to contain directories 64to scan for shared libraries. 65Each directory's pathname must start on a new 66line. 67Blank lines and lines starting with the comment character 68.Ql \&# 69are ignored. 70Filenames must conform to the 71.Pa lib*.so.[0-9] 72pattern in order to be added to the hints file. 73.Pp 74For security reasons, directories which are world or group-writable or which 75are not owned by root produce warning messages and are skipped, unless 76the 77.Fl i 78option is present. 79.Pp 80The shared libraries which are found will be automatically available for loading 81if needed by the program being prepared for execution. 82This obviates the need 83for storing search paths within the executable. 84.Pp 85The 86.Ev LD_LIBRARY_PATH 87environment variable can be used to override the use of 88directories (or the order thereof) from the cache or to specify additional 89directories where shared libraries might be found. 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 103.Nm 104utility is typically run as part of the boot sequence. 105.Pp 106The following options are recognized by 107.Nm : 108.Bl -tag -width indent 109.It Fl 32 110Generate the hints for 32-bit ABI shared libraries 111on 64-bit systems that support running 32-bit binaries. 112.It Fl elf 113Ignored for backwards compatibility. 114.It Fl R 115Rescan the previously configured directories. 116This opens the previous hints 117file and fetches the directory list from the header. 118Any additional pathnames 119on the command line are also processed. 120This is the default action when no parameters are given. 121.It Fl f Ar hints_file 122Read and/or update the specified hints file, instead of the standard file. 123This option is provided primarily for testing. 124.It Fl i 125Run in insecure mode. 126The security checks will not be performed. 127.It Fl m 128Instead of replacing the contents of the hints file 129with those found in the directories specified, 130.Dq merge 131in new entries. 132Directories recorded in the hints file by previous runs of 133.Nm 134are also rescanned for new shared libraries. 135.It Fl r 136List the current contents of the hints file 137on the standard output. 138The hints file is not modified. 139The list of 140directories stored in the hints file is included. 141.It Fl s 142Do not scan the built-in system directory 143.Pq Dq /usr/lib 144for shared libraries. 145.It Fl v 146Switch on verbose mode. 147.El 148.Sh SECURITY 149Special care must be taken when loading shared libraries into the address 150space of 151.Ev set-user-Id 152programs. 153Whenever such a program is run by any user except the owner of the program, 154the dynamic linker 155will only load shared libraries from the hints 156file. 157In particular, the 158.Ev LD_LIBRARY_PATH 159is not used to search for libraries. 160Thus, the role of 161.Nm 162is dual. 163In addition to building a set of hints for quick lookup, it also serves to 164specify the trusted collection of directories from which shared objects can 165be safely loaded. 166.Sh FILES 167.Bl -tag -width /var/run/ld-elf.so.hintsxxx -compact 168.It Pa /var/run/ld.so.hints 169Standard hints file for the a.out dynamic linker. 170.It Pa /var/run/ld-elf.so.hints 171Standard hints file for the ELF dynamic linker. 172.It Pa /etc/ld.so.conf 173Conventional configuration file containing directory names for 174invocations with 175.Fl aout . 176.It Pa /etc/ld-elf.so.conf 177Conventional configuration file containing directory names for 178invocations with 179.Fl elf . 180.It Pa /var/run/ld-elf32.so.hints 181.It Pa /var/run/ld32.so.hints 182Conventional configuration files containing directory names for 183invocations with 184.Fl 32 . 185.El 186.Sh SEE ALSO 187.Xr ld 1 , 188.Xr link 5 189.Sh HISTORY 190A 191.Nm 192utility first appeared in SunOS 4.0, it appeared in its current form 193in 194.Fx 1.1 . 195.Sh BUGS 196Some security checks (for example, verifying root ownership of 197added directories) are not performed when 198.Fl aout 199is specified. 200