chapter06/glibc.xml

   1 <?xml version="1.0" encoding="ISO-8859-1"?>
   2 <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
   4   <!ENTITY % general-entities SYSTEM "../general.ent">
   5   %general-entities;
   6 ]>
   7
   8 <sect1 id="ch-system-glibc" role="wrap">
   9   <?dbhtml filename="glibc.html"?>
  10
  11   <sect1info condition="script">
  12     <productname>glibc</productname>
  13     <productnumber>&glibc-version;</productnumber>
  14     <address>&glibc-url;</address>
  15   </sect1info>
  16
  17   <title>Glibc-&glibc-version;</title>
  18
  19   <indexterm zone="ch-system-glibc">
  20     <primary sortas="a-Glibc">Glibc</primary>
  21   </indexterm>
  22
  23   <sect2 role="package">
  24     <title/>
  25
  26     <para>The Glibc package contains the main C library. This library provides
  27     the basic routines for allocating memory, searching directories, opening and
  28     closing files, reading and writing files, string handling, pattern matching,
  29     arithmetic, and so on.</para>
  30
  31     <segmentedlist>
  32       <segtitle>&buildtime;</segtitle>
  33       <segtitle>&diskspace;</segtitle>
  34
  35       <seglistitem>
  36         <seg>&glibc-ch6-sbu;</seg>
  37         <seg>&glibc-ch6-du;</seg>
  38       </seglistitem>
  39     </segmentedlist>
  40
  41   </sect2>
  42
  43   <sect2 role="installation">
  44     <title>Installation of Glibc</title>
  45
  46     <note><para>The Glibc build system is self-contained and will install
  47     perfectly, even though the compiler specs file and linker are still
  48     pointing to <filename class="directory">/tools</filename>. The specs
  49     and linker cannot be adjusted before the Glibc install because the
  50     Glibc autoconf tests would give false results and defeat the goal
  51     of achieving a clean build.</para></note>
  52
  53     <para>Some of the Glibc programs use non-FHS compilant
  54     <filename class="directory">/var/db</filename> directory to store
  55     their runtime data. Apply the following patch to make such programs
  56     store their runtime data in the FHS-compliant locations:</para>
  57
  58 <screen><userinput remap="pre">patch -Np1 -i ../&glibc-fhs-patch;</userinput></screen>
  59
  60     <para>First create a compatibility symlink to avoid references to /tools in
  61     our final glibc:</para>
  62
  63 <screen><userinput remap="pre">ln -sfv /tools/lib/gcc /usr/lib</userinput></screen>
  64
  65     <para>Determine the GCC include directory and create a symlink for LSB
  66     compliance. Additionally, for x86_64, create a compatibility symlink
  67     required for the dynamic loader to function correctly:</para>
  68
  69 <screen><userinput remap="pre">case $(uname -m) in
  70     i?86)    GCC_INCDIR=/usr/lib/gcc/$(uname -m)-pc-linux-gnu/&gcc-version;/include
  71             ln -sfv ld-linux.so.2 /lib/ld-lsb.so.3
  72     ;;
  73     x86_64) GCC_INCDIR=/usr/lib/gcc/x86_64-pc-linux-gnu/&gcc-version;/include
  74             ln -sfv ../lib/ld-linux-x86-64.so.2 /lib64
  75             ln -sfv ../lib/ld-linux-x86-64.so.2 /lib64/ld-lsb-x86-64.so.3
  76     ;;
  77 esac</userinput></screen>
  78
  79     <para>Remove a file that may be left over from a previous build attempt:
  80     </para>
  81
  82 <screen><userinput remap="pre">rm -f /usr/include/limits.h</userinput></screen>
  83
  84     <para>The Glibc documentation recommends building Glibc
  85     in a dedicated build directory:</para>
  86
  87 <screen><userinput remap="pre">mkdir -v build
  88 cd       build</userinput></screen>
  89
  90     <para>Prepare Glibc for compilation:</para>
  91
  92 <screen><userinput remap="configure">CC="gcc -isystem $GCC_INCDIR -isystem /usr/include" \
  93 ../configure --prefix=/usr                          \
  94              --disable-werror                       \
  95              --enable-kernel=&min-kernel;                    \
  96              --enable-obsolete-rpc                  \
  97              --enable-stack-protector=strong        \
  98              libc_cv_slibdir=/lib
  99 unset GCC_INCDIR</userinput></screen>
 100
 101    <variablelist>
 102       <title>The meaning of the options and new configure parameters:</title>
 103
 104       <varlistentry>
 105         <term><parameter>CC="gcc -isystem $GCC_INCDIR -isystem /usr/include"</parameter></term>
 106         <listitem>
 107           <para>Setting the location of both gcc and system include directories
 108           avoids introduction of invalid paths in debugging symbols.</para>
 109         </listitem>
 110       </varlistentry>
 111
 112       <varlistentry>
 113         <term><parameter>--disable-werror</parameter></term>
 114         <listitem>
 115           <para>This option disables the -Werror option passed to
 116           GCC.  This is necessary for running the test suite.</para>
 117         </listitem>
 118       </varlistentry>
 119
 120       <varlistentry>
 121         <term><parameter>--enable-obsolete-rpc</parameter></term>
 122         <listitem>
 123           <para>This option builds older RPC code for use with
 124           network file system utilities (nfs).</para>
 125         </listitem>
 126       </varlistentry>
 127
 128       <varlistentry>
 129         <term><parameter>--enable-stack-protector=strong</parameter></term>
 130         <listitem>
 131           <para>This option increases system security by adding  a known canary
 132           (a random integer) to the stack during a function preamble, and checks
 133           it when the function returns. If it changed, there was a stack
 134           overflow, and the program aborts.</para>
 135         </listitem>
 136       </varlistentry>
 137
 138       <varlistentry>
 139         <term><parameter>libc_cv_slibdir=/lib</parameter></term>
 140         <listitem>
 141           <para>This variable sets the correct library for all
 142           systems.  We do not want lib64 to be used.</para>
 143         </listitem>
 144       </varlistentry>
 145
 146     </variablelist>
 147
 148     <para>Compile the package:</para>
 149
 150 <screen><userinput remap="make">make</userinput></screen>
 151
 152     <important>
 153       <para>In this section, the test suite for Glibc is considered critical.
 154       Do not skip it under any circumstance.</para>
 155     </important>
 156
 157     <para>Generally a few tests do not pass, but you can generally ignore
 158     any of the test failures listed below. Now test the build results:</para>
 159
 160 <screen><userinput remap="test">make check</userinput></screen>
 161
 162     <para>You may see some test failures.  The Glibc test suite is
 163     somewhat dependent on the host system.  This is a list of the most common
 164     issues seen for some versions of LFS:</para>
 165
 166     <itemizedlist>
 167
 168       <listitem>
 169         <para><emphasis>posix/tst-getaddrinfo4</emphasis> and
 170         <emphasis>posix/tst-getaddrinfo5</emphasis>
 171         may fail on some architectures.</para>
 172       </listitem>
 173
 174       <listitem>
 175         <para>The <emphasis>rt/tst-cputimer1</emphasis> and
 176         <emphasis>rt/tst-cpuclock2</emphasis> tests have been known to
 177         fail.  The reason is not completely understood, but indications are
 178         that minor timing issues can trigger these failures.</para>
 179       </listitem>
 180
 181       <listitem>
 182         <para>The math tests sometimes fail when running on
 183         systems where the CPU is not a relatively new Intel or
 184         AMD processor.</para>
 185       </listitem>
 186
 187       <listitem>
 188         <para>The
 189         <emphasis>nptl/tst-thread-affinity-{pthread,pthread2,sched}</emphasis>
 190         tests may fail for reasons that have not been determined.  </para>
 191       </listitem>
 192
 193       <listitem>
 194         <para>Other tests known to fail on some architectures are
 195         malloc/tst-malloc-usable and nptl/tst-cleanupx4. </para>
 196       </listitem>
 197
 198     </itemizedlist>
 199
 200     <para>Though it is a harmless message, the install stage of Glibc will
 201     complain about the absence of <filename>/etc/ld.so.conf</filename>.
 202     Prevent this warning with:</para>
 203
 204 <screen><userinput remap="install">touch /etc/ld.so.conf</userinput></screen>
 205
 206     <para>Fix the generated Makefile to skip an uneeded sanity check
 207     that fails in the LFS partial environment:
 208     </para>
 209
 210 <screen><userinput remap="install">sed '/test-installation/s@$(PERL)@echo not running@' -i ../Makefile</userinput></screen>
 211
 212     <para>Install the package:</para>
 213
 214 <screen><userinput remap="install">make install</userinput></screen>
 215
 216     <para>Install the configuration file and runtime directory for
 217     <command>nscd</command>:</para>
 218
 219 <screen><userinput remap="install">cp -v ../nscd/nscd.conf /etc/nscd.conf
 220 mkdir -pv /var/cache/nscd</userinput></screen>
 221
 222     <para revision="systemd">Install the systemd support files for
 223     <command>nscd</command>:</para>
 224
 225     <screen revision="systemd"><userinput remap="install">install -v -Dm644 ../nscd/nscd.tmpfiles /usr/lib/tmpfiles.d/nscd.conf
 226 install -v -Dm644 ../nscd/nscd.service /lib/systemd/system/nscd.service</userinput></screen>
 227
 228     <para>Next, install the locales that can make the system respond in a
 229     different language.  None of the locales are required, but if some of them
 230     are missing, the test suites of future packages would skip important
 231     testcases.</para>
 232
 233     <para>Individual locales can be installed using the
 234     <command>localedef</command> program. E.g., the first
 235     <command>localedef</command> command below combines the
 236     <filename>/usr/share/i18n/locales/cs_CZ</filename>
 237     charset-independent locale definition with the
 238     <filename>/usr/share/i18n/charmaps/UTF-8.gz</filename>
 239     charmap definition and appends the result to the
 240     <filename>/usr/lib/locale/locale-archive</filename> file.
 241     The following instructions will install the minimum set of
 242     locales necessary for the optimal coverage of tests:</para>
 243
 244 <screen role="nodump"><userinput remap="locale-test">mkdir -pv /usr/lib/locale
 245 localedef -i cs_CZ -f UTF-8 cs_CZ.UTF-8
 246 localedef -i de_DE -f ISO-8859-1 de_DE
 247 localedef -i de_DE@euro -f ISO-8859-15 de_DE@euro
 248 localedef -i de_DE -f UTF-8 de_DE.UTF-8
 249 localedef -i en_GB -f UTF-8 en_GB.UTF-8
 250 localedef -i en_HK -f ISO-8859-1 en_HK
 251 localedef -i en_PH -f ISO-8859-1 en_PH
 252 localedef -i en_US -f ISO-8859-1 en_US
 253 localedef -i en_US -f UTF-8 en_US.UTF-8
 254 localedef -i es_MX -f ISO-8859-1 es_MX
 255 localedef -i fa_IR -f UTF-8 fa_IR
 256 localedef -i fr_FR -f ISO-8859-1 fr_FR
 257 localedef -i fr_FR@euro -f ISO-8859-15 fr_FR@euro
 258 localedef -i fr_FR -f UTF-8 fr_FR.UTF-8
 259 localedef -i it_IT -f ISO-8859-1 it_IT
 260 localedef -i it_IT -f UTF-8 it_IT.UTF-8
 261 localedef -i ja_JP -f EUC-JP ja_JP
 262 localedef -i ru_RU -f KOI8-R ru_RU.KOI8-R
 263 localedef -i ru_RU -f UTF-8 ru_RU.UTF-8
 264 localedef -i tr_TR -f UTF-8 tr_TR.UTF-8
 265 localedef -i zh_CN -f GB18030 zh_CN.GB18030</userinput></screen>
 266
 267     <para>In addition, install the locale for your own country, language and
 268     character set.</para>
 269
 270     <para>Alternatively, install all locales listed in the
 271     <filename>glibc-&glibc-version;/localedata/SUPPORTED</filename> file
 272     (it includes every locale listed above and many more) at once with the
 273     following time-consuming command:</para>
 274
 275 <screen><userinput remap="locale-full">make localedata/install-locales</userinput></screen>
 276
 277     <para>Then use the <command>localedef</command> command to create and
 278     install locales not listed in the
 279     <filename>glibc-&glibc-version;/localedata/SUPPORTED</filename> file
 280     in the unlikely case you need them.</para>
 281
 282   </sect2>
 283
 284   <sect2 id="conf-glibc" role="configuration">
 285     <title>Configuring Glibc</title>
 286
 287     <indexterm zone="conf-glibc">
 288       <primary sortas="e-/etc/nsswitch.conf">/etc/nsswitch.conf</primary>
 289     </indexterm>
 290
 291     <indexterm zone="conf-glibc">
 292       <primary sortas="e-/etc/localtime">/etc/localtime</primary>
 293     </indexterm>
 294
 295   <sect3>
 296   <title>Adding nsswitch.conf</title>
 297
 298     <para>The <filename>/etc/nsswitch.conf</filename> file needs to be created
 299     because the Glibc defaults do not work well in a networked environment.
 300     </para>
 301
 302     <para>Create a new file <filename>/etc/nsswitch.conf</filename> by running the
 303     following:</para>
 304
 305 <screen><userinput>cat &gt; /etc/nsswitch.conf &lt;&lt; "EOF"
 306 <literal># Begin /etc/nsswitch.conf
 307
 308 passwd: files
 309 group: files
 310 shadow: files
 311
 312 hosts: files dns
 313 networks: files
 314
 315 protocols: files
 316 services: files
 317 ethers: files
 318 rpc: files
 319
 320 # End /etc/nsswitch.conf</literal>
 321 EOF</userinput></screen>
 322
 323     </sect3>
 324
 325     <sect3>
 326     <title>Adding time zone data</title>
 327
 328     <para>Install and set up the time zone data with the following:</para>
 329 <screen><userinput>tar -xf ../../tzdata&tzdata-version;.tar.gz
 330
 331 ZONEINFO=/usr/share/zoneinfo
 332 mkdir -pv $ZONEINFO/{posix,right}
 333
 334 for tz in etcetera southamerica northamerica europe africa antarctica  \
 335           asia australasia backward pacificnew systemv; do
 336     zic -L /dev/null   -d $ZONEINFO       -y "sh yearistype.sh" ${tz}
 337     zic -L /dev/null   -d $ZONEINFO/posix -y "sh yearistype.sh" ${tz}
 338     zic -L leapseconds -d $ZONEINFO/right -y "sh yearistype.sh" ${tz}
 339 done
 340
 341 cp -v zone.tab zone1970.tab iso3166.tab $ZONEINFO
 342 zic -d $ZONEINFO -p America/New_York
 343 unset ZONEINFO</userinput></screen>
 344
 345     <variablelist>
 346       <title>The meaning of the zic commands:</title>
 347
 348       <varlistentry>
 349         <term><parameter>zic -L /dev/null ...</parameter></term>
 350         <listitem>
 351           <para>This creates posix time zones, without any leap seconds.  It is
 352           conventional to put these in both
 353           <filename class="directory">zoneinfo</filename> and
 354           <filename class="directory">zoneinfo/posix</filename>. It is
 355           necessary to put the POSIX time zones in
 356           <filename class="directory">zoneinfo</filename>, otherwise various
 357           test-suites will report errors. On an embedded system, where space is
 358           tight and you do not intend to ever update the time zones, you could save
 359           1.9MB by not using the <filename class="directory">posix</filename>
 360           directory, but some applications or test-suites might produce some
 361           failures.</para>
 362         </listitem>
 363       </varlistentry>
 364       <varlistentry>
 365         <term><parameter>zic -L leapseconds ...</parameter></term>
 366         <listitem>
 367           <para>This creates right time zones, including leap seconds. On an
 368           embedded system, where space is tight and you do not intend to
 369           ever update the time zones, or care about the correct time, you could
 370           save 1.9MB by omitting the <filename class="directory">right</filename>
 371           directory.</para>
 372         </listitem>
 373       </varlistentry>
 374       <varlistentry>
 375         <term><parameter>zic ... -p ...</parameter></term>
 376         <listitem>
 377           <para>This creates the <filename>posixrules</filename> file. We use
 378           New York because POSIX requires the daylight savings time rules
 379           to be in accordance with US rules.</para>
 380         </listitem>
 381       </varlistentry>
 382     </variablelist>
 383
 384
 385     <para>One way to determine the local time zone is to run the following
 386     script:</para>
 387
 388 <screen role="nodump"><userinput>tzselect</userinput></screen>
 389
 390     <para>After answering a few questions about the location, the script will
 391     output the name of the time zone (e.g.,
 392     <emphasis>America/Edmonton</emphasis>). There are also some other possible
 393     time zones listed in <filename
 394     class='directory'>/usr/share/zoneinfo</filename> such as
 395     <emphasis>Canada/Eastern</emphasis> or <emphasis>EST5EDT</emphasis> that
 396     are not identified by the script but can be used.</para>
 397
 398     <para>Then create the <filename>/etc/localtime</filename> file by
 399     running:</para>
 400
 401 <screen revision="sysv"><userinput>cp -v /usr/share/zoneinfo/<replaceable>&lt;xxx&gt;</replaceable> /etc/localtime</userinput></screen>
 402
 403 <screen revision="systemd"><userinput>ln -sfv /usr/share/zoneinfo/<replaceable>&lt;xxx&gt;</replaceable> /etc/localtime</userinput></screen>
 404
 405     <para>Replace <replaceable>&lt;xxx&gt;</replaceable> with the name of the
 406     time zone selected (e.g., Canada/Eastern).</para>
 407
 408   </sect3>
 409
 410   <sect3 id="conf-ld" role="configuration">
 411     <title>Configuring the Dynamic Loader</title>
 412
 413     <indexterm zone="conf-ld">
 414       <primary sortas="e-/etc/ld.so.conf">/etc/ld.so.conf</primary>
 415     </indexterm>
 416
 417     <para>By default, the dynamic loader (<filename
 418     class="libraryfile">/lib/ld-linux.so.2</filename>) searches through
 419     <filename class="directory">/lib</filename> and <filename
 420     class="directory">/usr/lib</filename> for dynamic libraries that are
 421     needed by programs as they are run. However, if there are libraries in
 422     directories other than <filename class="directory">/lib</filename> and
 423     <filename class="directory">/usr/lib</filename>, these need to be added
 424     to the <filename>/etc/ld.so.conf</filename> file in order for the
 425     dynamic loader to find them. Two directories that are commonly known
 426     to contain additional libraries are <filename
 427     class="directory">/usr/local/lib</filename> and <filename
 428     class="directory">/opt/lib</filename>, so add those directories to the
 429     dynamic loader's search path.</para>
 430
 431     <para>Create a new file <filename>/etc/ld.so.conf</filename> by running the
 432     following:</para>
 433
 434 <screen><userinput>cat &gt; /etc/ld.so.conf &lt;&lt; "EOF"
 435 <literal># Begin /etc/ld.so.conf
 436 /usr/local/lib
 437 /opt/lib
 438 </literal>
 439 EOF</userinput></screen>
 440
 441   <para>If desired, the dynamic loader can also search a directory and
 442   include the contents of files found there.  Generally the files in
 443   this include directory are one line specifying the desired library path.
 444   To add this capability run the following commands:</para>
 445
 446 <screen role="nodump"><userinput>cat &gt;&gt; /etc/ld.so.conf &lt;&lt; "EOF"
 447 <literal># Add an include directory
 448 include /etc/ld.so.conf.d/*.conf
 449 </literal>
 450 EOF
 451 mkdir -pv /etc/ld.so.conf.d</userinput></screen>
 452
 453   </sect3>
 454   </sect2>
 455
 456   <sect2 id="contents-glibc" role="content">
 457     <title>Contents of Glibc</title>
 458
 459     <segmentedlist>
 460       <segtitle>Installed programs</segtitle>
 461       <segtitle>Installed libraries</segtitle>
 462       <segtitle>Installed directories</segtitle>
 463
 464       <seglistitem>
 465         <seg>catchsegv, gencat, getconf, getent, iconv, iconvconfig, ldconfig,
 466         ldd, lddlibc4, locale, localedef, makedb, mtrace, nscd,
 467         pldd, rpcgen, sln, sotruss, sprof, tzselect, xtrace,
 468         zdump, and zic</seg>
 469         <seg>ld-&glibc-version;.so, libBrokenLocale.{a,so}, libSegFault.so, libanl.{a,so},
 470         libc.{a,so}, libc_nonshared.a, libcidn.so,
 471         libcrypt.{a,so}, libdl.{a,so}, libg.a, libieee.a, libm.{a,so},
 472         libmcheck.a, libmemusage.so, libnsl.{a,so}, libnss_compat.so,
 473         libnss_dns.so, libnss_files.so, libnss_hesiod.so, libnss_nis.so,
 474         libnss_nisplus.so, libpthread.{a,so},
 475         libpthread_nonshared.a, libresolv.{a,so}, librpcsvc.a, librt.{a,so},
 476         libthread_db.so, and libutil.{a,so}</seg>
 477         <seg>/usr/include/arpa, /usr/include/bits, /usr/include/gnu,
 478         /usr/include/net, /usr/include/netash, /usr/include/netatalk,
 479         /usr/include/netax25, /usr/include/neteconet, /usr/include/netinet,
 480         /usr/include/netipx, /usr/include/netiucv, /usr/include/netpacket,
 481         /usr/include/netrom, /usr/include/netrose, /usr/include/nfs,
 482         /usr/include/protocols, /usr/include/rpc, /usr/include/rpcsvc,
 483         /usr/include/sys, /usr/lib/audit, /usr/lib/gconv, /usr/lib/locale,
 484         /usr/libexec/getconf, /usr/share/i18n, /usr/share/zoneinfo,
 485         /var/cache/nscd, and /var/lib/nss_db</seg>
 486       </seglistitem>
 487     </segmentedlist>
 488
 489     <variablelist>
 490       <bridgehead renderas="sect3">Short Descriptions</bridgehead>
 491       <?dbfo list-presentation="list"?>
 492       <?dbhtml list-presentation="table"?>
 493
 494       <varlistentry id="catchsegv">
 495         <term><command>catchsegv</command></term>
 496         <listitem>
 497           <para>Can be used to create a stack trace when a program
 498           terminates with a segmentation fault</para>
 499           <indexterm zone="ch-system-glibc catchsegv">
 500             <primary sortas="b-catchsegv">catchsegv</primary>
 501           </indexterm>
 502         </listitem>
 503       </varlistentry>
 504
 505       <varlistentry id="gencat">
 506         <term><command>gencat</command></term>
 507         <listitem>
 508           <para>Generates message catalogues</para>
 509           <indexterm zone="ch-system-glibc gencat">
 510             <primary sortas="b-gencat">gencat</primary>
 511           </indexterm>
 512         </listitem>
 513       </varlistentry>
 514
 515       <varlistentry id="getconf">
 516         <term><command>getconf</command></term>
 517         <listitem>
 518           <para>Displays the system configuration values for file system
 519           specific variables</para>
 520           <indexterm zone="ch-system-glibc getconf">
 521             <primary sortas="b-getconf">getconf</primary>
 522           </indexterm>
 523         </listitem>
 524       </varlistentry>
 525
 526       <varlistentry id="getent">
 527         <term><command>getent</command></term>
 528         <listitem>
 529           <para>Gets entries from an administrative database</para>
 530           <indexterm zone="ch-system-glibc getent">
 531             <primary sortas="b-getent">getent</primary>
 532           </indexterm>
 533         </listitem>
 534       </varlistentry>
 535
 536       <varlistentry id="iconv">
 537         <term><command>iconv</command></term>
 538         <listitem>
 539           <para>Performs character set conversion</para>
 540           <indexterm zone="ch-system-glibc iconv">
 541             <primary sortas="b-iconv">iconv</primary>
 542           </indexterm>
 543         </listitem>
 544       </varlistentry>
 545
 546       <varlistentry id="iconvconfig">
 547         <term><command>iconvconfig</command></term>
 548         <listitem>
 549           <para>Creates fastloading <command>iconv</command> module configuration
 550           files</para>
 551           <indexterm zone="ch-system-glibc iconvconfig">
 552             <primary sortas="b-iconvconfig">iconvconfig</primary>
 553           </indexterm>
 554         </listitem>
 555       </varlistentry>
 556
 557       <varlistentry id="ldconfig">
 558         <term><command>ldconfig</command></term>
 559         <listitem>
 560           <para>Configures the dynamic linker runtime bindings</para>
 561           <indexterm zone="ch-system-glibc ldconfig">
 562             <primary sortas="b-ldconfig">ldconfig</primary>
 563           </indexterm>
 564         </listitem>
 565       </varlistentry>
 566
 567       <varlistentry id="ldd">
 568         <term><command>ldd</command></term>
 569         <listitem>
 570           <para>Reports which shared libraries are required
 571           by each given program or shared library</para>
 572           <indexterm zone="ch-system-glibc ldd">
 573             <primary sortas="b-ldd">ldd</primary>
 574           </indexterm>
 575         </listitem>
 576       </varlistentry>
 577
 578       <varlistentry id="lddlibc4">
 579         <term><command>lddlibc4</command></term>
 580         <listitem>
 581           <para>Assists <command>ldd</command> with object files</para>
 582           <indexterm zone="ch-system-glibc lddlibc4">
 583             <primary sortas="b-lddlibc4">lddlibc4</primary>
 584           </indexterm>
 585         </listitem>
 586       </varlistentry>
 587
 588       <varlistentry id="locale">
 589         <term><command>locale</command></term>
 590         <listitem>
 591           <para>Prints various information about the current locale</para>
 592           <indexterm zone="ch-system-glibc locale">
 593             <primary sortas="b-locale">locale</primary>
 594           </indexterm>
 595         </listitem>
 596       </varlistentry>
 597
 598       <varlistentry id="localedef">
 599         <term><command>localedef</command></term>
 600         <listitem>
 601           <para>Compiles locale specifications</para>
 602           <indexterm zone="ch-system-glibc localedef">
 603             <primary sortas="b-localedef">localedef</primary>
 604           </indexterm>
 605         </listitem>
 606       </varlistentry>
 607
 608       <varlistentry id="makedb">
 609         <term><command>makedb</command></term>
 610         <listitem>
 611           <para>Creates a simple database from textual input</para>
 612           <indexterm zone="ch-system-glibc makedb">
 613             <primary sortas="b-makedb">makedb</primary>
 614           </indexterm>
 615         </listitem>
 616       </varlistentry>
 617
 618       <varlistentry id="mtrace">
 619         <term><command>mtrace</command></term>
 620         <listitem>
 621           <para>Reads and interprets a memory trace file and displays a summary
 622           in human-readable format</para>
 623           <indexterm zone="ch-system-glibc mtrace">
 624             <primary sortas="b-mtrace">mtrace</primary>
 625           </indexterm>
 626         </listitem>
 627       </varlistentry>
 628
 629       <varlistentry id="nscd">
 630         <term><command>nscd</command></term>
 631         <listitem>
 632           <para>A daemon that provides a cache for the most common name
 633           service requests</para>
 634           <indexterm zone="ch-system-glibc nscd">
 635             <primary sortas="b-nscd">nscd</primary>
 636           </indexterm>
 637         </listitem>
 638       </varlistentry>
 639
 640       <varlistentry id="pldd">
 641         <term><command>pldd</command></term>
 642         <listitem>
 643           <para>Lists dynamic shared objects used by running processes</para>
 644           <indexterm zone="ch-system-glibc pldd">
 645             <primary sortas="b-pldd">pldd</primary>
 646           </indexterm>
 647         </listitem>
 648       </varlistentry>
 649
 650       <varlistentry id="rpcgen">
 651         <term><command>rpcgen</command></term>
 652         <listitem>
 653           <para>Generates C code to implement the Remote Procedure Call (RPC)
 654           protocol</para>
 655           <indexterm zone="ch-system-glibc rpcgen">
 656             <primary sortas="b-rpcgen">rpcgen</primary>
 657           </indexterm>
 658         </listitem>
 659       </varlistentry>
 660
 661       <varlistentry id="sln">
 662         <term><command>sln</command></term>
 663         <listitem>
 664           <para>A statically linked <command>ln</command> program</para>
 665           <indexterm zone="ch-system-glibc sln">
 666             <primary sortas="b-sln">sln</primary>
 667           </indexterm>
 668         </listitem>
 669       </varlistentry>
 670
 671       <varlistentry id="sotruss">
 672         <term><command>sotruss</command></term>
 673         <listitem>
 674           <para>Traces shared library procedure calls of a specified command</para>
 675           <indexterm zone="ch-system-glibc sotruss">
 676             <primary sortas="b-sotruss">sotruss</primary>
 677           </indexterm>
 678         </listitem>
 679       </varlistentry>
 680
 681       <varlistentry id="sprof">
 682         <term><command>sprof</command></term>
 683         <listitem>
 684           <para>Reads and displays shared object profiling data</para>
 685           <indexterm zone="ch-system-glibc sprof">
 686             <primary sortas="b-sprof">sprof</primary>
 687           </indexterm>
 688         </listitem>
 689       </varlistentry>
 690
 691       <varlistentry id="tzselect">
 692         <term><command>tzselect</command></term>
 693         <listitem>
 694           <para>Asks the user about the location of the system and reports
 695           the corresponding time zone description</para>
 696           <indexterm zone="ch-system-glibc tzselect">
 697             <primary sortas="b-tzselect">tzselect</primary>
 698           </indexterm>
 699         </listitem>
 700       </varlistentry>
 701
 702       <varlistentry id="xtrace">
 703         <term><command>xtrace</command></term>
 704         <listitem>
 705           <para>Traces the execution of a program by printing the currently
 706           executed function</para>
 707           <indexterm zone="ch-system-glibc xtrace">
 708             <primary sortas="b-xtrace">xtrace</primary>
 709           </indexterm>
 710         </listitem>
 711       </varlistentry>
 712
 713       <varlistentry id="zdump">
 714         <term><command>zdump</command></term>
 715         <listitem>
 716           <para>The time zone dumper</para>
 717           <indexterm zone="ch-system-glibc zdump">
 718             <primary sortas="b-zdump">zdump</primary>
 719           </indexterm>
 720         </listitem>
 721       </varlistentry>
 722
 723       <varlistentry id="zic">
 724         <term><command>zic</command></term>
 725         <listitem>
 726           <para>The time zone compiler</para>
 727           <indexterm zone="ch-system-glibc zic">
 728             <primary sortas="b-zic">zic</primary>
 729           </indexterm>
 730         </listitem>
 731       </varlistentry>
 732
 733       <varlistentry id="ld.so">
 734         <term><filename class="libraryfile">ld-&glibc-version;.so</filename></term>
 735         <listitem>
 736           <para>The helper program for shared library executables</para>
 737           <indexterm zone="ch-system-glibc ld.so">
 738             <primary sortas="c-ld.so">ld-&glibc-version;.so</primary>
 739           </indexterm>
 740         </listitem>
 741       </varlistentry>
 742
 743       <varlistentry id="libBrokenLocale">
 744         <term><filename class="libraryfile">libBrokenLocale</filename></term>
 745         <listitem>
 746           <para>Used internally by Glibc as a gross hack to get broken programs
 747           (e.g., some Motif applications) running. See comments in
 748           <filename>glibc-&glibc-version;/locale/broken_cur_max.c</filename>
 749           for more information</para>
 750           <indexterm zone="ch-system-glibc libBrokenLocale">
 751             <primary sortas="c-libBrokenLocale">libBrokenLocale</primary>
 752           </indexterm>
 753         </listitem>
 754       </varlistentry>
 755
 756       <varlistentry id="libSegFault">
 757         <term><filename class="libraryfile">libSegFault</filename></term>
 758         <listitem>
 759           <para>The segmentation fault signal handler, used by
 760           <command>catchsegv</command></para>
 761           <indexterm zone="ch-system-glibc libSegFault">
 762             <primary sortas="c-libSegFault">libSegFault</primary>
 763           </indexterm>
 764         </listitem>
 765       </varlistentry>
 766
 767       <varlistentry id="libanl">
 768         <term><filename class="libraryfile">libanl</filename></term>
 769         <listitem>
 770           <para>An asynchronous name lookup library</para>
 771           <indexterm zone="ch-system-glibc libanl">
 772             <primary sortas="c-libanl">libanl</primary>
 773           </indexterm>
 774         </listitem>
 775       </varlistentry>
 776
 777       <varlistentry id="libc">
 778         <term><filename class="libraryfile">libc</filename></term>
 779         <listitem>
 780           <para>The main C library</para>
 781           <indexterm zone="ch-system-glibc libc">
 782             <primary sortas="c-libc">libc</primary>
 783           </indexterm>
 784         </listitem>
 785       </varlistentry>
 786
 787       <varlistentry id="libcidn">
 788         <term><filename class="libraryfile">libcidn</filename></term>
 789         <listitem>
 790           <para>Used internally by Glibc for handling internationalized domain
 791           names in the <function>getaddrinfo()</function> function</para>
 792           <indexterm zone="ch-system-glibc libcidn">
 793             <primary sortas="c-libcidn">libcidn</primary>
 794           </indexterm>
 795         </listitem>
 796       </varlistentry>
 797
 798       <varlistentry id="libcrypt">
 799         <term><filename class="libraryfile">libcrypt</filename></term>
 800         <listitem>
 801           <para>The cryptography library</para>
 802           <indexterm zone="ch-system-glibc libcrypt">
 803             <primary sortas="c-libcrypt">libcrypt</primary>
 804           </indexterm>
 805         </listitem>
 806       </varlistentry>
 807
 808       <varlistentry id="libdl">
 809         <term><filename class="libraryfile">libdl</filename></term>
 810         <listitem>
 811           <para>The dynamic linking interface library</para>
 812           <indexterm zone="ch-system-glibc libdl">
 813             <primary sortas="c-libdl">libdl</primary>
 814           </indexterm>
 815         </listitem>
 816       </varlistentry>
 817
 818       <varlistentry id="libg">
 819         <term><filename class="libraryfile">libg</filename></term>
 820         <listitem>
 821           <para>Dummy library containing no functions. Previously was a runtime
 822           library for <command>g++</command></para>
 823           <indexterm zone="ch-system-glibc libg">
 824             <primary sortas="c-libg">libg</primary>
 825           </indexterm>
 826         </listitem>
 827       </varlistentry>
 828
 829       <varlistentry id="libieee">
 830         <term><filename class="libraryfile">libieee</filename></term>
 831         <listitem>
 832           <para>Linking in this module forces error handling rules for math
 833           functions as defined by the Institute of Electrical and Electronic
 834           Engineers (IEEE). The default is POSIX.1 error handling</para>
 835           <indexterm zone="ch-system-glibc libieee">
 836             <primary sortas="c-libieee">libieee</primary>
 837           </indexterm>
 838         </listitem>
 839       </varlistentry>
 840
 841       <varlistentry id="libm">
 842         <term><filename class="libraryfile">libm</filename></term>
 843         <listitem>
 844           <para>The mathematical library</para>
 845           <indexterm zone="ch-system-glibc libm">
 846             <primary sortas="c-libm">libm</primary>
 847           </indexterm>
 848         </listitem>
 849       </varlistentry>
 850
 851       <varlistentry id="libmcheck">
 852         <term><filename class="libraryfile">libmcheck</filename></term>
 853         <listitem>
 854           <para>Turns on memory allocation checking when linked to</para>
 855           <indexterm zone="ch-system-glibc libmcheck">
 856             <primary sortas="c-libmcheck">libmcheck</primary>
 857           </indexterm>
 858         </listitem>
 859       </varlistentry>
 860
 861       <varlistentry id="libmemusage">
 862         <term><filename class="libraryfile">libmemusage</filename></term>
 863         <listitem>
 864           <para>Used by <command>memusage</command> to help collect
 865           information about the memory usage of a program</para>
 866           <indexterm zone="ch-system-glibc libmemusage">
 867             <primary sortas="c-libmemusage">libmemusage</primary>
 868           </indexterm>
 869         </listitem>
 870       </varlistentry>
 871
 872       <varlistentry id="libnsl">
 873         <term><filename class="libraryfile">libnsl</filename></term>
 874         <listitem>
 875           <para>The network services library</para>
 876           <indexterm zone="ch-system-glibc libnsl">
 877             <primary sortas="c-libnsl">libnsl</primary>
 878           </indexterm>
 879         </listitem>
 880       </varlistentry>
 881
 882       <varlistentry id="libnss">
 883         <term><filename class="libraryfile">libnss</filename></term>
 884         <listitem>
 885           <para>The Name Service Switch libraries, containing functions for
 886           resolving host names, user names, group names, aliases, services,
 887           protocols, etc.</para>
 888           <indexterm zone="ch-system-glibc libnss">
 889             <primary sortas="c-libnss">libnss</primary>
 890           </indexterm>
 891         </listitem>
 892       </varlistentry>
 893
 894       <varlistentry id="libpthread">
 895         <term><filename class="libraryfile">libpthread</filename></term>
 896         <listitem>
 897           <para>The POSIX threads library</para>
 898           <indexterm zone="ch-system-glibc libpthread">
 899             <primary sortas="c-libpthread">libpthread</primary>
 900           </indexterm>
 901         </listitem>
 902       </varlistentry>
 903
 904       <varlistentry id="libresolv">
 905         <term><filename class="libraryfile">libresolv</filename></term>
 906         <listitem>
 907           <para>Contains functions for creating, sending, and interpreting
 908           packets to the Internet domain name servers</para>
 909           <indexterm zone="ch-system-glibc libresolv">
 910             <primary sortas="c-libresolv">libresolv</primary>
 911           </indexterm>
 912         </listitem>
 913       </varlistentry>
 914
 915       <varlistentry id="librpcsvc">
 916         <term><filename class="libraryfile">librpcsvc</filename></term>
 917         <listitem>
 918           <para>Contains functions providing miscellaneous RPC services</para>
 919           <indexterm zone="ch-system-glibc librpcsvc">
 920             <primary sortas="c-librpcsvc">librpcsvc</primary>
 921           </indexterm>
 922         </listitem>
 923       </varlistentry>
 924
 925       <varlistentry id="librt">
 926         <term><filename class="libraryfile">librt</filename></term>
 927         <listitem>
 928           <para>Contains functions providing most of the interfaces specified
 929           by the POSIX.1b Realtime Extension</para>
 930           <indexterm zone="ch-system-glibc librt">
 931             <primary sortas="c-librt">librt</primary>
 932           </indexterm>
 933         </listitem>
 934       </varlistentry>
 935
 936       <varlistentry id="libthread_db">
 937         <term><filename class="libraryfile">libthread_db</filename></term>
 938         <listitem>
 939           <para>Contains functions useful for building debuggers for
 940           multi-threaded programs</para>
 941           <indexterm zone="ch-system-glibc libthread_db">
 942             <primary sortas="c-libthread_db">libthread_db</primary>
 943           </indexterm>
 944         </listitem>
 945       </varlistentry>
 946
 947       <varlistentry id="libutil">
 948         <term><filename class="libraryfile">libutil</filename></term>
 949         <listitem>
 950           <para>Contains code for <quote>standard</quote> functions used in
 951           many different Unix utilities</para>
 952           <indexterm zone="ch-system-glibc libutil">
 953             <primary sortas="c-libutil">libutil</primary>
 954           </indexterm>
 955         </listitem>
 956       </varlistentry>
 957
 958     </variablelist>
 959
 960   </sect2>
 961
 962 </sect1>