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.\" $Id$ 31.\" 32.Dd October 3, 1993 33.Dt LDCONFIG 8 34.Os FreeBSD 35.Sh NAME 36.Nm ldconfig 37.Nd configure the shared library cache 38.Sh SYNOPSIS 39.Nm ldconfig 40.Op Fl rsv 41.Op Ar directory Ar ... 42.Sh DESCRIPTION 43.Nm 44is used to prepare a set of 45.Dq hints 46for use by the run-time linker 47.Xr ld.so 48to facilitate quick lookup of shared libraries available in multiple 49directories. It scans a set of built-in system directories and any 50.Ar directories 51specified on the command line (in the given order) looking for shared 52libraries and stores the results in the file 53.Xr /var/run/ld.so.hints 54to forestall the overhead that would otherwise result from the 55directory search operations 56.Xr ld.so 57would have to perform to load the required shared libraries. 58.Pp 59The shared libraries so found will be automatically available for loading 60if needed by the program being prepared for execution. This obviates the need 61for storing search paths within the executable. 62.Pp 63The 64.Ev LD_LIBRARY_PATH 65environment variable can be used to override the use of 66directories (or the order thereof) from the cache or to specify additional 67directories where shared libraries might be found. 68.Ev LD_LIBRARY_PATH 69is a 70.Sq \: 71separated list of directory paths which are searched by 72.Xr ld.so 73when it needs to load a shared library. It can be viewed as the run-time 74equivalent of the 75.Fl L 76switch of 77.Xr ld. 78.Pp 79.Nm Ldconfig 80is typically run as part of the boot sequence. 81.Pp 82The following options recognized by 83.Nm ldconfig: 84.Bl -tag -width indent 85.It Fl r 86Lists the current contents of 87.Xr ld.so.hints 88on the standard output. The hints file will not be modified. 89.It Fl s 90Do not scan the built-in system directory 91.Pq Dq /usr/lib 92for shared libraries. 93.It Fl v 94Switch on verbose mode. 95.Sh Security 96Special care must be taken when loading shared libraries into the address 97space of 98.Ev set-user-Id 99programs. Whenever such a program is run, 100.Xr ld.so 101will only load shared libraries from the 102.Ev ld.so.hints 103file. In particular, the 104.Ev LD_LIBRARY_PATH 105is not used to search for libraries. Thus, the role of ldconfig is dual. In 106addition to building a set of hints for quick lookup, it also serves to 107specify the trusted collection of directories from which shared objects can 108be safely loaded. It is presumed that the set of directories specified to 109.Nm ldconfig 110are under control of the system's administrator. 111.Xr ld.so 112further assists set-user-Id programs by erasing the 113.Ev LD_LIBRARY_PATH 114from the environment. 115 116.Sh FILES 117.Xr /var/run/ld.so.hints 118.Sh SEE ALSO 119.Xr ld 1 , 120.Xr link 5 121.Sh HISTORY 122A 123.Nm 124utility first appeared in SunOS 4.0, it appeared in its current form 125in FreeBSD 1.1. 126