BOOK/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 the 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>Fix a minor security issue with glob functions:</para>
  61
  62 <screen><userinput remap="pre">patch -Np1 -i ../&glibc-glob-patch;</userinput></screen>
  63 -->
  64     <para>Fix a problem introduced with the linux-5.2 kernel:</para>
  65
  66 <screen><userinput remap="pre">sed -i '/asm.socket.h/a# include &lt;linux/sockios.h&gt;' \
  67    sysdeps/unix/sysv/linux/bits/socket.h</userinput></screen>
  68
  69     <para>Create a symlink for LSB
  70     compliance. Additionally, for x86_64, create a compatibility symlink
  71     required for the dynamic loader to function correctly:</para>
  72
  73 <screen><userinput remap="pre">case $(uname -m) in
  74     i?86)   ln -sfv ld-linux.so.2 /lib/ld-lsb.so.3
  75     ;;
  76     x86_64) ln -sfv ../lib/ld-linux-x86-64.so.2 /lib64
  77             ln -sfv ../lib/ld-linux-x86-64.so.2 /lib64/ld-lsb-x86-64.so.3
  78     ;;
  79 esac</userinput></screen>
  80 <!--
  81     <para>Remove a file that may be left over from a previous build attempt:
  82     </para>
  83
  84 <screen><userinput remap="pre">rm -f /usr/include/limits.h</userinput></screen>
  85 -->
  86     <para>The Glibc documentation recommends building Glibc
  87     in a dedicated build directory:</para>
  88
  89 <screen><userinput remap="pre">mkdir -v build
  90 cd       build</userinput></screen>
  91
  92     <para>Prepare Glibc for compilation:</para>
  93
  94 <screen><userinput remap="configure">CC="gcc -ffile-prefix-map=/tools=/usr" \
  95 ../configure --prefix=/usr                          \
  96              --disable-werror                       \
  97              --enable-kernel=&min-kernel;                    \
  98              --enable-stack-protector=strong        \
  99              --with-headers=/usr/include            \
 100              libc_cv_slibdir=/lib</userinput></screen>
 101
 102    <variablelist>
 103       <title>The meaning of the options and new configure parameters:</title>
 104
 105       <varlistentry>
 106         <term><parameter>CC="gcc -ffile-prefix-map=/tools=/usr"</parameter></term>
 107         <listitem>
 108           <para>Make GCC record any references to files in /tools in result
 109           of the compilation as if the files resided in /usr.  This avoids
 110           introduction of invalid paths in debugging symbols.</para>
 111         </listitem>
 112       </varlistentry>
 113
 114       <varlistentry>
 115         <term><parameter>--disable-werror</parameter></term>
 116         <listitem>
 117           <para>This option disables the -Werror option passed to
 118           GCC.  This is necessary for running the test suite.</para>
 119         </listitem>
 120       </varlistentry>
 121
 122       <varlistentry>
 123         <term><parameter>--enable-stack-protector=strong</parameter></term>
 124         <listitem>
 125           <para>This option increases system security by adding
 126           extra code to check for buffer overflows, such as stack
 127           smashing attacks.</para>
 128         </listitem>
 129       </varlistentry>
 130
 131       <varlistentry>
 132         <term><parameter>--with-headers=/usr/include</parameter></term>
 133         <listitem>
 134           <para>This option tells the build system where to find the
 135           kernel API headers. By default, those headers are sought in
 136           <filename class="directory">/tools/include</filename>.</para>
 137         </listitem>
 138       </varlistentry>
 139
 140       <varlistentry>
 141         <term><parameter>libc_cv_slibdir=/lib</parameter></term>
 142         <listitem>
 143           <para>This variable sets the correct library for all
 144           systems.  We do not want lib64 to be used.</para>
 145         </listitem>
 146       </varlistentry>
 147
 148     </variablelist>
 149
 150     <para>Compile the package:</para>
 151
 152 <screen><userinput remap="make">make</userinput></screen>
 153
 154     <important>
 155       <para>In this section, the test suite for Glibc is considered critical.
 156       Do not skip it under any circumstance.</para>
 157     </important>
 158
 159     <para>Generally a few tests do not pass. The test failures listed below
 160     are usually safe to ignore.</para>
 161
 162 <!-- Use remap="make" here to work around a jhalfs issue. -->
 163 <screen><userinput remap="make">case $(uname -m) in
 164   i?86)   ln -sfnv $PWD/elf/ld-linux.so.2        /lib ;;
 165   x86_64) ln -sfnv $PWD/elf/ld-linux-x86-64.so.2 /lib ;;
 166 esac</userinput></screen>
 167
 168     <note><para>The symbolic link above is needed to run the tests at this
 169     stage of building in the chroot environment.  It will be overwritten
 170     in the install phase below.</para></note>
 171
 172 <screen><userinput remap="test">make check</userinput></screen>
 173
 174     <para>You may see some test failures.  The Glibc test suite is
 175     somewhat dependent on the host system.  This is a list of the most common
 176     issues seen for some versions of LFS:</para>
 177
 178     <itemizedlist>
 179
 180       <listitem>
 181         <para><emphasis>misc/tst-ttyname</emphasis>
 182         is known to fail in the LFS chroot environment.</para>
 183       </listitem>
 184
 185       <listitem>
 186         <para><emphasis>inet/tst-idna_name_classify</emphasis>
 187         is known to fail in the LFS chroot environment.</para>
 188       </listitem>
 189
 190       <listitem>
 191         <para><emphasis>posix/tst-getaddrinfo4</emphasis> and
 192         <emphasis>posix/tst-getaddrinfo5</emphasis>
 193         may fail on some architectures.</para>
 194       </listitem>
 195
 196       <listitem>
 197         <para>The <emphasis>nss/tst-nss-files-hosts-multi</emphasis>
 198         test may fail for reasons that have not been determined.</para>
 199       </listitem>
 200
 201       <listitem>
 202         <para>The <emphasis>rt/tst-cputimer{1,2,3}</emphasis> tests depend on
 203         the host system kernel. Kernels 4.14.91&ndash;4.14.96,
 204         4.19.13&ndash;4.19.18, and 4.20.0&ndash;4.20.5 are known to
 205         cause these tests to fail.
 206         </para>
 207       </listitem>
 208
 209       <listitem>
 210         <para>The math tests sometimes fail when running on
 211         systems where the CPU is not a relatively new Intel or
 212         AMD processor.</para>
 213       </listitem>
 214 <!--
 215       <listitem>
 216         <para>The
 217         <emphasis>nptl/tst-thread-affinity-{pthread,pthread2,sched}</emphasis>
 218         tests may fail for reasons that have not been determined.  </para>
 219       </listitem>
 220
 221       <listitem>
 222         <para>Other tests known to fail on some architectures are
 223         malloc/tst-malloc-usable and nptl/tst-cleanupx4. </para>
 224       </listitem>
 225 -->
 226     </itemizedlist>
 227
 228     <para>Though it is a harmless message, the install stage of Glibc will
 229     complain about the absence of <filename>/etc/ld.so.conf</filename>.
 230     Prevent this warning with:</para>
 231
 232 <screen><userinput remap="install">touch /etc/ld.so.conf</userinput></screen>
 233
 234     <para>Fix the generated Makefile to skip an unneeded sanity check
 235     that fails in the LFS partial environment:
 236     </para>
 237
 238 <screen><userinput remap="install">sed '/test-installation/s@$(PERL)@echo not running@' -i ../Makefile</userinput></screen>
 239
 240     <para>Install the package:</para>
 241
 242 <screen><userinput remap="install">make install</userinput></screen>
 243
 244     <para>Install the configuration file and runtime directory for
 245     <command>nscd</command>:</para>
 246
 247 <screen><userinput remap="install">cp -v ../nscd/nscd.conf /etc/nscd.conf
 248 mkdir -pv /var/cache/nscd</userinput></screen>
 249
 250     <para revision="systemd">Install the systemd support files for
 251     <command>nscd</command>:</para>
 252
 253     <screen revision="systemd"><userinput remap="install">install -v -Dm644 ../nscd/nscd.tmpfiles /usr/lib/tmpfiles.d/nscd.conf
 254 install -v -Dm644 ../nscd/nscd.service /lib/systemd/system/nscd.service</userinput></screen>
 255
 256     <para>Next, install the locales that can make the system respond in a
 257     different language.  None of the locales are required, but if some of them
 258     are missing, the test suites of future packages would skip important
 259     testcases.</para>
 260
 261     <para>Individual locales can be installed using the
 262     <command>localedef</command> program. E.g., the first
 263     <command>localedef</command> command below combines the
 264     <filename>/usr/share/i18n/locales/cs_CZ</filename>
 265     charset-independent locale definition with the
 266     <filename>/usr/share/i18n/charmaps/UTF-8.gz</filename>
 267     charmap definition and appends the result to the
 268     <filename>/usr/lib/locale/locale-archive</filename> file.
 269     The following instructions will install the minimum set of
 270     locales necessary for the optimal coverage of tests:</para>
 271
 272 <screen role="nodump"><userinput remap="locale-test">mkdir -pv /usr/lib/locale
 273 localedef -i POSIX -f UTF-8 C.UTF-8 2> /dev/null || true
 274 localedef -i cs_CZ -f UTF-8 cs_CZ.UTF-8
 275 localedef -i de_DE -f ISO-8859-1 de_DE
 276 localedef -i de_DE@euro -f ISO-8859-15 de_DE@euro
 277 localedef -i de_DE -f UTF-8 de_DE.UTF-8
 278 localedef -i el_GR -f ISO-8859-7 el_GR
 279 localedef -i en_GB -f UTF-8 en_GB.UTF-8
 280 localedef -i en_HK -f ISO-8859-1 en_HK
 281 localedef -i en_PH -f ISO-8859-1 en_PH
 282 localedef -i en_US -f ISO-8859-1 en_US
 283 localedef -i en_US -f UTF-8 en_US.UTF-8
 284 localedef -i es_MX -f ISO-8859-1 es_MX
 285 localedef -i fa_IR -f UTF-8 fa_IR
 286 localedef -i fr_FR -f ISO-8859-1 fr_FR
 287 localedef -i fr_FR@euro -f ISO-8859-15 fr_FR@euro
 288 localedef -i fr_FR -f UTF-8 fr_FR.UTF-8
 289 localedef -i it_IT -f ISO-8859-1 it_IT
 290 localedef -i it_IT -f UTF-8 it_IT.UTF-8
 291 localedef -i ja_JP -f EUC-JP ja_JP
 292 localedef -i ja_JP -f SHIFT_JIS ja_JP.SIJS 2> /dev/null || true
 293 localedef -i ja_JP -f UTF-8 ja_JP.UTF-8
 294 localedef -i ru_RU -f KOI8-R ru_RU.KOI8-R
 295 localedef -i ru_RU -f UTF-8 ru_RU.UTF-8
 296 localedef -i tr_TR -f UTF-8 tr_TR.UTF-8
 297 localedef -i zh_CN -f GB18030 zh_CN.GB18030
 298 localedef -i zh_HK -f BIG5-HKSCS zh_HK.BIG5-HKSCS</userinput></screen>
 299
 300     <para>In addition, install the locale for your own country, language and
 301     character set.</para>
 302
 303     <para>Alternatively, install all locales listed in the
 304     <filename>glibc-&glibc-version;/localedata/SUPPORTED</filename> file
 305     (it includes every locale listed above and many more) at once with the
 306     following time-consuming command:</para>
 307
 308 <screen><userinput remap="locale-full">make localedata/install-locales</userinput></screen>
 309
 310     <para>Then use the <command>localedef</command> command to create and
 311     install locales not listed in the
 312     <filename>glibc-&glibc-version;/localedata/SUPPORTED</filename> file
 313     in the unlikely case you need them.</para>
 314
 315     <note><para>Glibc now uses libidn2 when resolving internationalized
 316     domain names.  This is a run time dependency.  If this capability
 317     is needed, the instructions for installing libidn2 are in the
 318     <ulink url="&blfs-book;general/libidn2.html">BLFS libidn2 page</ulink>.
 319     </para></note>
 320
 321   </sect2>
 322
 323   <sect2 id="conf-glibc" role="configuration">
 324     <title>Configuring Glibc</title>
 325
 326     <indexterm zone="conf-glibc">
 327       <primary sortas="e-/etc/nsswitch.conf">/etc/nsswitch.conf</primary>
 328     </indexterm>
 329
 330     <indexterm zone="conf-glibc">
 331       <primary sortas="e-/etc/localtime">/etc/localtime</primary>
 332     </indexterm>
 333
 334   <sect3>
 335   <title>Adding nsswitch.conf</title>
 336
 337     <para>The <filename>/etc/nsswitch.conf</filename> file needs to be created
 338     because the Glibc defaults do not work well in a networked environment.
 339     </para>
 340
 341     <para>Create a new file <filename>/etc/nsswitch.conf</filename> by running the
 342     following:</para>
 343
 344 <screen><userinput>cat &gt; /etc/nsswitch.conf &lt;&lt; "EOF"
 345 <literal># Begin /etc/nsswitch.conf
 346
 347 passwd: files
 348 group: files
 349 shadow: files
 350
 351 hosts: files dns
 352 networks: files
 353
 354 protocols: files
 355 services: files
 356 ethers: files
 357 rpc: files
 358
 359 # End /etc/nsswitch.conf</literal>
 360 EOF</userinput></screen>
 361
 362     </sect3>
 363
 364     <sect3>
 365     <title>Adding time zone data</title>
 366
 367     <para>Install and set up the time zone data with the following:</para>
 368 <screen><userinput>tar -xf ../../tzdata&tzdata-version;.tar.gz
 369
 370 ZONEINFO=/usr/share/zoneinfo
 371 mkdir -pv $ZONEINFO/{posix,right}
 372
 373 for tz in etcetera southamerica northamerica europe africa antarctica  \
 374           asia australasia backward pacificnew systemv; do
 375     zic -L /dev/null   -d $ZONEINFO       ${tz}
 376     zic -L /dev/null   -d $ZONEINFO/posix ${tz}
 377     zic -L leapseconds -d $ZONEINFO/right ${tz}
 378 done
 379
 380 cp -v zone.tab zone1970.tab iso3166.tab $ZONEINFO
 381 zic -d $ZONEINFO -p America/New_York
 382 unset ZONEINFO</userinput></screen>
 383
 384     <variablelist>
 385       <title>The meaning of the zic commands:</title>
 386
 387       <varlistentry>
 388         <term><parameter>zic -L /dev/null ...</parameter></term>
 389         <listitem>
 390           <para>This creates posix time zones, without any leap seconds.  It is
 391           conventional to put these in both
 392           <filename class="directory">zoneinfo</filename> and
 393           <filename class="directory">zoneinfo/posix</filename>. It is
 394           necessary to put the POSIX time zones in
 395           <filename class="directory">zoneinfo</filename>, otherwise various
 396           test-suites will report errors. On an embedded system, where space is
 397           tight and you do not intend to ever update the time zones, you could save
 398           1.9MB by not using the <filename class="directory">posix</filename>
 399           directory, but some applications or test-suites might produce some
 400           failures.</para>
 401         </listitem>
 402       </varlistentry>
 403       <varlistentry>
 404         <term><parameter>zic -L leapseconds ...</parameter></term>
 405         <listitem>
 406           <para>This creates right time zones, including leap seconds. On an
 407           embedded system, where space is tight and you do not intend to
 408           ever update the time zones, or care about the correct time, you could
 409           save 1.9MB by omitting the <filename class="directory">right</filename>
 410           directory.</para>
 411         </listitem>
 412       </varlistentry>
 413       <varlistentry>
 414         <term><parameter>zic ... -p ...</parameter></term>
 415         <listitem>
 416           <para>This creates the <filename>posixrules</filename> file. We use
 417           New York because POSIX requires the daylight savings time rules
 418           to be in accordance with US rules.</para>
 419         </listitem>
 420       </varlistentry>
 421     </variablelist>
 422
 423
 424     <para>One way to determine the local time zone is to run the following
 425     script:</para>
 426
 427 <screen role="nodump"><userinput>tzselect</userinput></screen>
 428
 429     <para>After answering a few questions about the location, the script will
 430     output the name of the time zone (e.g.,
 431     <emphasis>America/Edmonton</emphasis>). There are also some other possible
 432     time zones listed in <filename
 433     class='directory'>/usr/share/zoneinfo</filename> such as
 434     <emphasis>Canada/Eastern</emphasis> or <emphasis>EST5EDT</emphasis> that
 435     are not identified by the script but can be used.</para>
 436
 437     <para>Then create the <filename>/etc/localtime</filename> file by
 438     running:</para>
 439
 440 <screen><userinput>ln -sfv /usr/share/zoneinfo/<replaceable>&lt;xxx&gt;</replaceable> /etc/localtime</userinput></screen>
 441
 442     <para>Replace <replaceable>&lt;xxx&gt;</replaceable> with the name of the
 443     time zone selected (e.g., Canada/Eastern).</para>
 444
 445   </sect3>
 446
 447   <sect3 id="conf-ld" role="configuration">
 448     <title>Configuring the Dynamic Loader</title>
 449
 450     <indexterm zone="conf-ld">
 451       <primary sortas="e-/etc/ld.so.conf">/etc/ld.so.conf</primary>
 452     </indexterm>
 453
 454     <para>By default, the dynamic loader (<filename
 455     class="libraryfile">/lib/ld-linux.so.2</filename>) searches through
 456     <filename class="directory">/lib</filename> and <filename
 457     class="directory">/usr/lib</filename> for dynamic libraries that are
 458     needed by programs as they are run. However, if there are libraries in
 459     directories other than <filename class="directory">/lib</filename> and
 460     <filename class="directory">/usr/lib</filename>, these need to be added
 461     to the <filename>/etc/ld.so.conf</filename> file in order for the
 462     dynamic loader to find them. Two directories that are commonly known
 463     to contain additional libraries are <filename
 464     class="directory">/usr/local/lib</filename> and <filename
 465     class="directory">/opt/lib</filename>, so add those directories to the
 466     dynamic loader's search path.</para>
 467
 468     <para>Create a new file <filename>/etc/ld.so.conf</filename> by running the
 469     following:</para>
 470
 471 <screen><userinput>cat &gt; /etc/ld.so.conf &lt;&lt; "EOF"
 472 <literal># Begin /etc/ld.so.conf
 473 /usr/local/lib
 474 /opt/lib
 475 </literal>
 476 EOF</userinput></screen>
 477
 478   <para>If desired, the dynamic loader can also search a directory and
 479   include the contents of files found there.  Generally the files in
 480   this include directory are one line specifying the desired library path.
 481   To add this capability run the following commands:</para>
 482
 483 <screen role="nodump"><userinput>cat &gt;&gt; /etc/ld.so.conf &lt;&lt; "EOF"
 484 <literal># Add an include directory
 485 include /etc/ld.so.conf.d/*.conf
 486 </literal>
 487 EOF
 488 mkdir -pv /etc/ld.so.conf.d</userinput></screen>
 489
 490   </sect3>
 491   </sect2>
 492
 493   <sect2 id="contents-glibc" role="content">
 494     <title>Contents of Glibc</title>
 495
 496     <segmentedlist>
 497       <segtitle>Installed programs</segtitle>
 498       <segtitle>Installed libraries</segtitle>
 499       <segtitle>Installed directories</segtitle>
 500
 501       <seglistitem>
 502         <seg>catchsegv, gencat, getconf, getent, iconv, iconvconfig, ldconfig,
 503         ldd, lddlibc4, locale, localedef, makedb, mtrace, nscd,
 504         pcprofiledump, pldd, sln, sotruss, sprof, tzselect, xtrace,
 505         zdump, and zic</seg>
 506         <seg>ld-&glibc-version;.so, libBrokenLocale.{a,so}, libSegFault.so, libanl.{a,so},
 507         libc.{a,so}, libc_nonshared.a,
 508         libcrypt.{a,so}, libdl.{a,so}, libg.a, libm.{a,so},
 509         libmcheck.a, libmemusage.so, libmvec.{a,so}, libnsl.{a,so},
 510         libnss_compat.so, libnss_dns.so, libnss_files.so, libnss_hesiod.so,
 511         libpcprofile.so, libpthread.{a,so},
 512         libpthread_nonshared.a, libresolv.{a,so}, librt.{a,so},
 513         libthread_db.so, and libutil.{a,so}</seg>
 514         <seg>/usr/include/arpa, /usr/include/bits, /usr/include/gnu,
 515         /usr/include/net, /usr/include/netash, /usr/include/netatalk,
 516         /usr/include/netax25, /usr/include/neteconet, /usr/include/netinet,
 517         /usr/include/netipx, /usr/include/netiucv, /usr/include/netpacket,
 518         /usr/include/netrom, /usr/include/netrose, /usr/include/nfs,
 519         /usr/include/protocols, /usr/include/rpc,
 520         /usr/include/sys, /usr/lib/audit, /usr/lib/gconv, /usr/lib/locale,
 521         /usr/libexec/getconf, /usr/share/i18n, /usr/share/zoneinfo,
 522         /var/cache/nscd, and /var/lib/nss_db</seg>
 523       </seglistitem>
 524     </segmentedlist>
 525
 526     <variablelist>
 527       <bridgehead renderas="sect3">Short Descriptions</bridgehead>
 528       <?dbfo list-presentation="list"?>
 529       <?dbhtml list-presentation="table"?>
 530
 531       <varlistentry id="catchsegv">
 532         <term><command>catchsegv</command></term>
 533         <listitem>
 534           <para>Can be used to create a stack trace when a program
 535           terminates with a segmentation fault</para>
 536           <indexterm zone="ch-system-glibc catchsegv">
 537             <primary sortas="b-catchsegv">catchsegv</primary>
 538           </indexterm>
 539         </listitem>
 540       </varlistentry>
 541
 542       <varlistentry id="gencat">
 543         <term><command>gencat</command></term>
 544         <listitem>
 545           <para>Generates message catalogues</para>
 546           <indexterm zone="ch-system-glibc gencat">
 547             <primary sortas="b-gencat">gencat</primary>
 548           </indexterm>
 549         </listitem>
 550       </varlistentry>
 551
 552       <varlistentry id="getconf">
 553         <term><command>getconf</command></term>
 554         <listitem>
 555           <para>Displays the system configuration values for file system
 556           specific variables</para>
 557           <indexterm zone="ch-system-glibc getconf">
 558             <primary sortas="b-getconf">getconf</primary>
 559           </indexterm>
 560         </listitem>
 561       </varlistentry>
 562
 563       <varlistentry id="getent">
 564         <term><command>getent</command></term>
 565         <listitem>
 566           <para>Gets entries from an administrative database</para>
 567           <indexterm zone="ch-system-glibc getent">
 568             <primary sortas="b-getent">getent</primary>
 569           </indexterm>
 570         </listitem>
 571       </varlistentry>
 572
 573       <varlistentry id="iconv">
 574         <term><command>iconv</command></term>
 575         <listitem>
 576           <para>Performs character set conversion</para>
 577           <indexterm zone="ch-system-glibc iconv">
 578             <primary sortas="b-iconv">iconv</primary>
 579           </indexterm>
 580         </listitem>
 581       </varlistentry>
 582
 583       <varlistentry id="iconvconfig">
 584         <term><command>iconvconfig</command></term>
 585         <listitem>
 586           <para>Creates fastloading <command>iconv</command> module configuration
 587           files</para>
 588           <indexterm zone="ch-system-glibc iconvconfig">
 589             <primary sortas="b-iconvconfig">iconvconfig</primary>
 590           </indexterm>
 591         </listitem>
 592       </varlistentry>
 593
 594       <varlistentry id="ldconfig">
 595         <term><command>ldconfig</command></term>
 596         <listitem>
 597           <para>Configures the dynamic linker runtime bindings</para>
 598           <indexterm zone="ch-system-glibc ldconfig">
 599             <primary sortas="b-ldconfig">ldconfig</primary>
 600           </indexterm>
 601         </listitem>
 602       </varlistentry>
 603
 604       <varlistentry id="ldd">
 605         <term><command>ldd</command></term>
 606         <listitem>
 607           <para>Reports which shared libraries are required
 608           by each given program or shared library</para>
 609           <indexterm zone="ch-system-glibc ldd">
 610             <primary sortas="b-ldd">ldd</primary>
 611           </indexterm>
 612         </listitem>
 613       </varlistentry>
 614
 615       <varlistentry id="lddlibc4">
 616         <term><command>lddlibc4</command></term>
 617         <listitem>
 618           <para>Assists <command>ldd</command> with object files</para>
 619           <indexterm zone="ch-system-glibc lddlibc4">
 620             <primary sortas="b-lddlibc4">lddlibc4</primary>
 621           </indexterm>
 622         </listitem>
 623       </varlistentry>
 624
 625       <varlistentry id="locale">
 626         <term><command>locale</command></term>
 627         <listitem>
 628           <para>Prints various information about the current locale</para>
 629           <indexterm zone="ch-system-glibc locale">
 630             <primary sortas="b-locale">locale</primary>
 631           </indexterm>
 632         </listitem>
 633       </varlistentry>
 634
 635       <varlistentry id="localedef">
 636         <term><command>localedef</command></term>
 637         <listitem>
 638           <para>Compiles locale specifications</para>
 639           <indexterm zone="ch-system-glibc localedef">
 640             <primary sortas="b-localedef">localedef</primary>
 641           </indexterm>
 642         </listitem>
 643       </varlistentry>
 644
 645       <varlistentry id="makedb">
 646         <term><command>makedb</command></term>
 647         <listitem>
 648           <para>Creates a simple database from textual input</para>
 649           <indexterm zone="ch-system-glibc makedb">
 650             <primary sortas="b-makedb">makedb</primary>
 651           </indexterm>
 652         </listitem>
 653       </varlistentry>
 654
 655       <varlistentry id="mtrace">
 656         <term><command>mtrace</command></term>
 657         <listitem>
 658           <para>Reads and interprets a memory trace file and displays a summary
 659           in human-readable format</para>
 660           <indexterm zone="ch-system-glibc mtrace">
 661             <primary sortas="b-mtrace">mtrace</primary>
 662           </indexterm>
 663         </listitem>
 664       </varlistentry>
 665
 666       <varlistentry id="nscd">
 667         <term><command>nscd</command></term>
 668         <listitem>
 669           <para>A daemon that provides a cache for the most common name
 670           service requests</para>
 671           <indexterm zone="ch-system-glibc nscd">
 672             <primary sortas="b-nscd">nscd</primary>
 673           </indexterm>
 674         </listitem>
 675       </varlistentry>
 676
 677       <varlistentry id="pcprofiledump">
 678         <term><command>pcprofiledump</command></term>
 679         <listitem>
 680           <para>Dump information generated by PC profiling</para>
 681           <indexterm zone="ch-system-glibc pcprofiledump">
 682             <primary sortas="b-pcprofiledump">pcprofiledump</primary>
 683           </indexterm>
 684         </listitem>
 685       </varlistentry>
 686
 687       <varlistentry id="pldd">
 688         <term><command>pldd</command></term>
 689         <listitem>
 690           <para>Lists dynamic shared objects used by running processes</para>
 691           <indexterm zone="ch-system-glibc pldd">
 692             <primary sortas="b-pldd">pldd</primary>
 693           </indexterm>
 694         </listitem>
 695       </varlistentry>
 696
 697       <varlistentry id="sln">
 698         <term><command>sln</command></term>
 699         <listitem>
 700           <para>A statically linked <command>ln</command> program</para>
 701           <indexterm zone="ch-system-glibc sln">
 702             <primary sortas="b-sln">sln</primary>
 703           </indexterm>
 704         </listitem>
 705       </varlistentry>
 706
 707       <varlistentry id="sotruss">
 708         <term><command>sotruss</command></term>
 709         <listitem>
 710           <para>Traces shared library procedure calls of a specified command</para>
 711           <indexterm zone="ch-system-glibc sotruss">
 712             <primary sortas="b-sotruss">sotruss</primary>
 713           </indexterm>
 714         </listitem>
 715       </varlistentry>
 716
 717       <varlistentry id="sprof">
 718         <term><command>sprof</command></term>
 719         <listitem>
 720           <para>Reads and displays shared object profiling data</para>
 721           <indexterm zone="ch-system-glibc sprof">
 722             <primary sortas="b-sprof">sprof</primary>
 723           </indexterm>
 724         </listitem>
 725       </varlistentry>
 726
 727       <varlistentry id="tzselect">
 728         <term><command>tzselect</command></term>
 729         <listitem>
 730           <para>Asks the user about the location of the system and reports
 731           the corresponding time zone description</para>
 732           <indexterm zone="ch-system-glibc tzselect">
 733             <primary sortas="b-tzselect">tzselect</primary>
 734           </indexterm>
 735         </listitem>
 736       </varlistentry>
 737
 738       <varlistentry id="xtrace">
 739         <term><command>xtrace</command></term>
 740         <listitem>
 741           <para>Traces the execution of a program by printing the currently
 742           executed function</para>
 743           <indexterm zone="ch-system-glibc xtrace">
 744             <primary sortas="b-xtrace">xtrace</primary>
 745           </indexterm>
 746         </listitem>
 747       </varlistentry>
 748
 749       <varlistentry id="zdump">
 750         <term><command>zdump</command></term>
 751         <listitem>
 752           <para>The time zone dumper</para>
 753           <indexterm zone="ch-system-glibc zdump">
 754             <primary sortas="b-zdump">zdump</primary>
 755           </indexterm>
 756         </listitem>
 757       </varlistentry>
 758
 759       <varlistentry id="zic">
 760         <term><command>zic</command></term>
 761         <listitem>
 762           <para>The time zone compiler</para>
 763           <indexterm zone="ch-system-glibc zic">
 764             <primary sortas="b-zic">zic</primary>
 765           </indexterm>
 766         </listitem>
 767       </varlistentry>
 768
 769       <varlistentry id="ld.so">
 770         <term><filename class="libraryfile">ld-&glibc-version;.so</filename></term>
 771         <listitem>
 772           <para>The helper program for shared library executables</para>
 773           <indexterm zone="ch-system-glibc ld.so">
 774             <primary sortas="c-ld.so">ld-&glibc-version;.so</primary>
 775           </indexterm>
 776         </listitem>
 777       </varlistentry>
 778
 779       <varlistentry id="libBrokenLocale">
 780         <term><filename class="libraryfile">libBrokenLocale</filename></term>
 781         <listitem>
 782           <para>Used internally by Glibc as a gross hack to get broken programs
 783           (e.g., some Motif applications) running. See comments in
 784           <filename>glibc-&glibc-version;/locale/broken_cur_max.c</filename>
 785           for more information</para>
 786           <indexterm zone="ch-system-glibc libBrokenLocale">
 787             <primary sortas="c-libBrokenLocale">libBrokenLocale</primary>
 788           </indexterm>
 789         </listitem>
 790       </varlistentry>
 791
 792       <varlistentry id="libSegFault">
 793         <term><filename class="libraryfile">libSegFault</filename></term>
 794         <listitem>
 795           <para>The segmentation fault signal handler, used by
 796           <command>catchsegv</command></para>
 797           <indexterm zone="ch-system-glibc libSegFault">
 798             <primary sortas="c-libSegFault">libSegFault</primary>
 799           </indexterm>
 800         </listitem>
 801       </varlistentry>
 802
 803       <varlistentry id="libanl">
 804         <term><filename class="libraryfile">libanl</filename></term>
 805         <listitem>
 806           <para>An asynchronous name lookup library</para>
 807           <indexterm zone="ch-system-glibc libanl">
 808             <primary sortas="c-libanl">libanl</primary>
 809           </indexterm>
 810         </listitem>
 811       </varlistentry>
 812
 813       <varlistentry id="libc">
 814         <term><filename class="libraryfile">libc</filename></term>
 815         <listitem>
 816           <para>The main C library</para>
 817           <indexterm zone="ch-system-glibc libc">
 818             <primary sortas="c-libc">libc</primary>
 819           </indexterm>
 820         </listitem>
 821       </varlistentry>
 822
 823       <varlistentry id="libcrypt">
 824         <term><filename class="libraryfile">libcrypt</filename></term>
 825         <listitem>
 826           <para>The cryptography library</para>
 827           <indexterm zone="ch-system-glibc libcrypt">
 828             <primary sortas="c-libcrypt">libcrypt</primary>
 829           </indexterm>
 830         </listitem>
 831       </varlistentry>
 832
 833       <varlistentry id="libdl">
 834         <term><filename class="libraryfile">libdl</filename></term>
 835         <listitem>
 836           <para>The dynamic linking interface library</para>
 837           <indexterm zone="ch-system-glibc libdl">
 838             <primary sortas="c-libdl">libdl</primary>
 839           </indexterm>
 840         </listitem>
 841       </varlistentry>
 842
 843       <varlistentry id="libg">
 844         <term><filename class="libraryfile">libg</filename></term>
 845         <listitem>
 846           <para>Dummy library containing no functions. Previously was a runtime
 847           library for <command>g++</command></para>
 848           <indexterm zone="ch-system-glibc libg">
 849             <primary sortas="c-libg">libg</primary>
 850           </indexterm>
 851         </listitem>
 852       </varlistentry>
 853
 854       <varlistentry id="libm">
 855         <term><filename class="libraryfile">libm</filename></term>
 856         <listitem>
 857           <para>The mathematical library</para>
 858           <indexterm zone="ch-system-glibc libm">
 859             <primary sortas="c-libm">libm</primary>
 860           </indexterm>
 861         </listitem>
 862       </varlistentry>
 863
 864       <varlistentry id="libmcheck">
 865         <term><filename class="libraryfile">libmcheck</filename></term>
 866         <listitem>
 867           <para>Turns on memory allocation checking when linked to</para>
 868           <indexterm zone="ch-system-glibc libmcheck">
 869             <primary sortas="c-libmcheck">libmcheck</primary>
 870           </indexterm>
 871         </listitem>
 872       </varlistentry>
 873
 874       <varlistentry id="libmemusage">
 875         <term><filename class="libraryfile">libmemusage</filename></term>
 876         <listitem>
 877           <para>Used by <command>memusage</command> to help collect
 878           information about the memory usage of a program</para>
 879           <indexterm zone="ch-system-glibc libmemusage">
 880             <primary sortas="c-libmemusage">libmemusage</primary>
 881           </indexterm>
 882         </listitem>
 883       </varlistentry>
 884
 885       <varlistentry id="libnsl">
 886         <term><filename class="libraryfile">libnsl</filename></term>
 887         <listitem>
 888           <para>The network services library</para>
 889           <indexterm zone="ch-system-glibc libnsl">
 890             <primary sortas="c-libnsl">libnsl</primary>
 891           </indexterm>
 892         </listitem>
 893       </varlistentry>
 894
 895       <varlistentry id="libnss">
 896         <term><filename class="libraryfile">libnss</filename></term>
 897         <listitem>
 898           <para>The Name Service Switch libraries, containing functions for
 899           resolving host names, user names, group names, aliases, services,
 900           protocols, etc.</para>
 901           <indexterm zone="ch-system-glibc libnss">
 902             <primary sortas="c-libnss">libnss</primary>
 903           </indexterm>
 904         </listitem>
 905       </varlistentry>
 906
 907       <varlistentry id="libpcprofile">
 908         <term><filename class="libraryfile">libpcprofile</filename></term>
 909         <listitem>
 910           <para>Can be preloaded to PC profile an executable</para>
 911           <indexterm zone="ch-system-glibc libpcprofile">
 912             <primary sortas="c-libpcprofile">libpcprofile</primary>
 913           </indexterm>
 914         </listitem>
 915       </varlistentry>
 916
 917       <varlistentry id="libpthread">
 918         <term><filename class="libraryfile">libpthread</filename></term>
 919         <listitem>
 920           <para>The POSIX threads library</para>
 921           <indexterm zone="ch-system-glibc libpthread">
 922             <primary sortas="c-libpthread">libpthread</primary>
 923           </indexterm>
 924         </listitem>
 925       </varlistentry>
 926
 927       <varlistentry id="libresolv">
 928         <term><filename class="libraryfile">libresolv</filename></term>
 929         <listitem>
 930           <para>Contains functions for creating, sending, and interpreting
 931           packets to the Internet domain name servers</para>
 932           <indexterm zone="ch-system-glibc libresolv">
 933             <primary sortas="c-libresolv">libresolv</primary>
 934           </indexterm>
 935         </listitem>
 936       </varlistentry>
 937
 938       <varlistentry id="librt">
 939         <term><filename class="libraryfile">librt</filename></term>
 940         <listitem>
 941           <para>Contains functions providing most of the interfaces specified
 942           by the POSIX.1b Realtime Extension</para>
 943           <indexterm zone="ch-system-glibc librt">
 944             <primary sortas="c-librt">librt</primary>
 945           </indexterm>
 946         </listitem>
 947       </varlistentry>
 948
 949       <varlistentry id="libthread_db">
 950         <term><filename class="libraryfile">libthread_db</filename></term>
 951         <listitem>
 952           <para>Contains functions useful for building debuggers for
 953           multi-threaded programs</para>
 954           <indexterm zone="ch-system-glibc libthread_db">
 955             <primary sortas="c-libthread_db">libthread_db</primary>
 956           </indexterm>
 957         </listitem>
 958       </varlistentry>
 959
 960       <varlistentry id="libutil">
 961         <term><filename class="libraryfile">libutil</filename></term>
 962         <listitem>
 963           <para>Contains code for <quote>standard</quote> functions used in
 964           many different Unix utilities</para>
 965           <indexterm zone="ch-system-glibc libutil">
 966             <primary sortas="c-libutil">libutil</primary>
 967           </indexterm>
 968         </listitem>
 969       </varlistentry>
 970
 971     </variablelist>
 972
 973   </sect2>
 974
 975 </sect1>