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 January 6, 2018 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 aout | 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 aout 113Generate the hints for a.out format shared libraries. 114.It Fl elf 115Generate the hints for ELF format shared libraries. 116.It Fl R 117Rescan the previously configured directories. 118This opens the previous hints 119file and fetches the directory list from the header. 120Any additional pathnames 121on the command line are also processed. 122This is the default action when no parameters are given. 123.It Fl f Ar hints_file 124Read and/or update the specified hints file, instead of the standard file. 125This option is provided primarily for testing. 126.It Fl i 127Run in insecure mode. 128The security checks will not be performed. 129.It Fl m 130Instead of replacing the contents of the hints file 131with those found in the directories specified, 132.Dq merge 133in new entries. 134Directories recorded in the hints file by previous runs of 135.Nm 136are also rescanned for new shared libraries. 137.It Fl r 138List the current contents of the hints file 139on the standard output. 140The hints file is not modified. 141The list of 142directories stored in the hints file is included. 143.It Fl s 144Do not scan the built-in system directory 145.Pq Dq /usr/lib 146for shared libraries. 147.It Fl v 148Switch on verbose mode. 149.El 150.Sh SECURITY 151Special care must be taken when loading shared libraries into the address 152space of 153.Ev set-user-Id 154programs. 155Whenever such a program is run by any user except the owner of the program, 156the dynamic linker 157will only load shared libraries from the hints 158file. 159In particular, the 160.Ev LD_LIBRARY_PATH 161is not used to search for libraries. 162Thus, the role of 163.Nm 164is dual. 165In addition to building a set of hints for quick lookup, it also serves to 166specify the trusted collection of directories from which shared objects can 167be safely loaded. 168.Sh FILES 169.Bl -tag -width /var/run/ld-elf.so.hintsxxx -compact 170.It Pa /var/run/ld.so.hints 171Standard hints file for the a.out dynamic linker. 172.It Pa /var/run/ld-elf.so.hints 173Standard hints file for the ELF dynamic linker. 174.It Pa /etc/ld.so.conf 175Conventional configuration file containing directory names for 176invocations with 177.Fl aout . 178.It Pa /etc/ld-elf.so.conf 179Conventional configuration file containing directory names for 180invocations with 181.Fl elf . 182.It Pa /var/run/ld-elf32.so.hints 183.It Pa /var/run/ld32.so.hints 184Conventional configuration files containing directory names for 185invocations with 186.Fl 32 . 187.El 188.Sh SEE ALSO 189.Xr ld 1 , 190.Xr link 5 191.Sh HISTORY 192A 193.Nm 194utility first appeared in SunOS 4.0, it appeared in its current form 195in 196.Fx 1.1 . 197.Sh BUGS 198Some security checks (for example, verifying root ownership of 199added directories) are not performed when 200.Fl aout 201is specified. 202