man8/ldconfig.8

   1 .\" Copyright 1999 SuSE GmbH Nuernberg, Germany
   2 .\" Author: Thorsten Kukuk <kukuk@suse.de>
   3 .\"
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  19 .\"
  20 .\" Modified, 6 May 2002, Michael Kerrisk, <mtk.manpages@gmail.com>
  21 .\"   Change listed order of /usr/lib and /lib
  22 .TH LDCONFIG 8 2017-09-15 "GNU" "Linux Programmer's Manual"
  23 .SH NAME
  24 ldconfig \- configure dynamic linker run-time bindings
  25 .SH SYNOPSIS
  26 .BR /sbin/ldconfig " [" \-nNvXV "] [" \-f " \fIconf\fP] [" \-C " \fIcache\fP] [" \-r " \fIroot\fP]"
  27 .IR directory \...
  28 .PD 0
  29 .PP
  30 .PD
  31 .B /sbin/ldconfig
  32 .B \-l
  33 .RB [ \-v ]
  34 .IR library \...
  35 .PD 0
  36 .PP
  37 .PD
  38 .B /sbin/ldconfig
  39 .B \-p
  40 .SH DESCRIPTION
  41 .B ldconfig
  42 creates the necessary links and cache to the most recent shared
  43 libraries found in the directories specified on the command line,
  44 in the file
  45 .IR /etc/ld.so.conf ,
  46 and in the trusted directories,
  47 .I /lib
  48 and
  49 .IR /usr/lib
  50 (on some 64-bit architectures such as x86-64,
  51 .I /lib
  52 and
  53 .IR /usr/lib
  54 are the trusted directories for 32-bit libraries, while
  55 .I /lib64
  56 and
  57 .IR /usr/lib64
  58 are used for 64-bit libraries).
  59 .PP
  60 The cache is used by the run-time linker,
  61 .I ld.so
  62 or
  63 .IR ld-linux.so .
  64 .B ldconfig
  65 checks the header and filenames of the libraries it encounters when
  66 determining which versions should have their links updated.
  67 .PP
  68 .B ldconfig
  69 will attempt to deduce the type of ELF libraries (i.e., libc5 or libc6/glibc)
  70 based on what C libraries, if any, the library was linked against.
  71 .\" The following sentence looks suspect
  72 .\" (perhaps historical cruft) -- MTK, Jul 2005
  73 .\" Therefore, when making dynamic libraries,
  74 .\" it is wise to explicitly link against libc (use \-lc).
  75 .PP
  76 Some existing libraries do not contain enough information
  77 to allow the deduction of their type.
  78 Therefore, the
  79 .I /etc/ld.so.conf
  80 file format allows the specification of an expected type.
  81 This is used
  82 .I only
  83 for those ELF libraries which we can not work out.
  84 The format
  85 is "dirname=TYPE", where TYPE can be libc4, libc5, or libc6.
  86 (This syntax also works on the command line.)
  87 Spaces are
  88 .I not
  89 allowed.
  90 Also see the
  91 .B \-p
  92 option.
  93 .B ldconfig
  94 should normally be run by the superuser as it may require write
  95 permission on some root owned directories and files.
  96 .SH OPTIONS
  97 .TP
  98 .BR \-c " \fIfmt\fP, " \-\-format=\fIfmt\fP
  99 (Since glibc 2.2)
 100 Cache format to use:
 101 .IR old ,
 102 .IR new ,
 103 or
 104 .IR compat
 105 (default).
 106 .TP
 107 .BI "\-C " cache
 108 Use
 109 .I cache
 110 instead of
 111 .IR /etc/ld.so.cache .
 112 .TP
 113 .BI "\-f " conf
 114 Use
 115 .I conf
 116 instead of
 117 .IR /etc/ld.so.conf .
 118 .\" FIXME glibc 2.7 added -i
 119 .TP
 120 .BR \-i ", " \-\-ignore\-aux\-cache
 121 (Since glibc 2.7)
 122 .\"             commit 27d9ffda17df4d2388687afd12897774fde39bcc
 123 Ignore auxiliary cache file.
 124 .TP
 125 .B \-l
 126 (Since glibc 2.2)
 127 Library mode.
 128 Manually link individual libraries.
 129 Intended for use by experts only.
 130 .TP
 131 .B \-n
 132 Process only the directories specified on the command line.
 133 Don't process the trusted directories,
 134 nor those specified in
 135 .IR /etc/ld.so.conf .
 136 Implies
 137 .BR \-N .
 138 .TP
 139 .B \-N
 140 Don't rebuild the cache.
 141 Unless
 142 .B \-X
 143 is also specified, links are still updated.
 144 .TP
 145 .BR \-p ", " \-\-print\-cache
 146 Print the lists of directories and candidate libraries stored in
 147 the current cache.
 148 .TP
 149 .BI "\-r " root
 150 Change to and use
 151 .I root
 152 as the root directory.
 153 .TP
 154 .BR \-v ", " \-\-verbose
 155 Verbose mode.
 156 Print current version number, the name of each directory as it
 157 is scanned, and any links that are created.
 158 Overrides quiet mode.
 159 .TP
 160 .BR \-V ", " \-\-version
 161 Print program version.
 162 .TP
 163 .B \-X
 164 Don't update links.
 165 Unless
 166 .B \-N
 167 is also specified, the cache is still rebuilt.
 168 .SH FILES
 169 .\" FIXME Since glibc-2.3.4, "include" directives are supported in ld.so.conf
 170 .\"
 171 .\" FIXME Since glibc-2.4, "hwcap" directives are supported in ld.so.conf
 172 .PD 0
 173 .TP
 174 .I /lib/ld.so
 175 Run-time linker/loader.
 176 .TP
 177 .I /etc/ld.so.conf
 178 File containing a list of directories, one per line,
 179 in which to search for libraries.
 180 .TP
 181 .I /etc/ld.so.cache
 182 File containing an ordered list of libraries found in the directories
 183 specified in
 184 .IR /etc/ld.so.conf ,
 185 as well as those found in the trusted directories.
 186 .PD
 187 .SH SEE ALSO
 188 .BR ldd (1),
 189 .BR ld.so (8)