lfs/chapter06/glibc.xml
Pierre Labastie 235556ae96 typos
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@11513 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
2019-02-07 15:23:51 +00:00

978 lines
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % general-entities SYSTEM "../general.ent">
%general-entities;
]>
<sect1 id="ch-system-glibc" role="wrap">
<?dbhtml filename="glibc.html"?>
<sect1info condition="script">
<productname>glibc</productname>
<productnumber>&glibc-version;</productnumber>
<address>&glibc-url;</address>
</sect1info>
<title>Glibc-&glibc-version;</title>
<indexterm zone="ch-system-glibc">
<primary sortas="a-Glibc">Glibc</primary>
</indexterm>
<sect2 role="package">
<title/>
<para>The Glibc package contains the main C library. This library provides
the basic routines for allocating memory, searching directories, opening and
closing files, reading and writing files, string handling, pattern matching,
arithmetic, and so on.</para>
<segmentedlist>
<segtitle>&buildtime;</segtitle>
<segtitle>&diskspace;</segtitle>
<seglistitem>
<seg>&glibc-ch6-sbu;</seg>
<seg>&glibc-ch6-du;</seg>
</seglistitem>
</segmentedlist>
</sect2>
<sect2 role="installation">
<title>Installation of Glibc</title>
<note><para>The Glibc build system is self-contained and will install
perfectly, even though the compiler specs file and linker are still
pointing to <filename class="directory">/tools</filename>. The specs
and linker cannot be adjusted before the Glibc install because the
Glibc autoconf tests would give false results and defeat the goal
of achieving a clean build.</para></note>
<para>Some of the Glibc programs use the non-FHS compilant
<filename class="directory">/var/db</filename> directory to store
their runtime data. Apply the following patch to make such programs
store their runtime data in the FHS-compliant locations:</para>
<screen><userinput remap="pre">patch -Np1 -i ../&glibc-fhs-patch;</userinput></screen>
<!--
<para>Fix a minor security issue with glob functions:</para>
<screen><userinput remap="pre">patch -Np1 -i ../&glibc-glob-patch;</userinput></screen>
-->
<para>First create a compatibility symlink to avoid references to /tools in
our final glibc:</para>
<screen><userinput remap="pre">ln -sfv /tools/lib/gcc /usr/lib</userinput></screen>
<para>Determine the GCC include directory and create a symlink for LSB
compliance. Additionally, for x86_64, create a compatibility symlink
required for the dynamic loader to function correctly:</para>
<screen><userinput remap="pre">case $(uname -m) in
i?86) GCC_INCDIR=/usr/lib/gcc/$(uname -m)-pc-linux-gnu/&gcc-version;/include
ln -sfv ld-linux.so.2 /lib/ld-lsb.so.3
;;
x86_64) GCC_INCDIR=/usr/lib/gcc/x86_64-pc-linux-gnu/&gcc-version;/include
ln -sfv ../lib/ld-linux-x86-64.so.2 /lib64
ln -sfv ../lib/ld-linux-x86-64.so.2 /lib64/ld-lsb-x86-64.so.3
;;
esac</userinput></screen>
<para>Remove a file that may be left over from a previous build attempt:
</para>
<screen><userinput remap="pre">rm -f /usr/include/limits.h</userinput></screen>
<para>The Glibc documentation recommends building Glibc
in a dedicated build directory:</para>
<screen><userinput remap="pre">mkdir -v build
cd build</userinput></screen>
<para>Prepare Glibc for compilation:</para>
<screen><userinput remap="configure">CC="gcc -isystem $GCC_INCDIR -isystem /usr/include" \
../configure --prefix=/usr \
--disable-werror \
--enable-kernel=&min-kernel; \
--enable-stack-protector=strong \
libc_cv_slibdir=/lib
unset GCC_INCDIR</userinput></screen>
<variablelist>
<title>The meaning of the options and new configure parameters:</title>
<varlistentry>
<term><parameter>CC="gcc -isystem $GCC_INCDIR -isystem /usr/include"</parameter></term>
<listitem>
<para>Setting the location of both gcc and system include directories
avoids introduction of invalid paths in debugging symbols.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>--disable-werror</parameter></term>
<listitem>
<para>This option disables the -Werror option passed to
GCC. This is necessary for running the test suite.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>--enable-stack-protector=strong</parameter></term>
<listitem>
<para>This option increases system security by adding
extra code to check for buffer overflows, such as stack
smashing attacks.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>libc_cv_slibdir=/lib</parameter></term>
<listitem>
<para>This variable sets the correct library for all
systems. We do not want lib64 to be used.</para>
</listitem>
</varlistentry>
</variablelist>
<para>Compile the package:</para>
<screen><userinput remap="make">make</userinput></screen>
<important>
<para>In this section, the test suite for Glibc is considered critical.
Do not skip it under any circumstance.</para>
</important>
<para>Generally a few tests do not pass. The test failures listed below
are usually safe to ignore.</para>
<!-- Use remap="make" here to work around a jhalfs issue. -->
<screen><userinput remap="make">case $(uname -m) in
i?86) ln -sfnv $PWD/elf/ld-linux.so.2 /lib ;;
x86_64) ln -sfnv $PWD/elf/ld-linux-x86-64.so.2 /lib ;;
esac</userinput></screen>
<note><para>The symbolic link above is needed to run the tests at this
stage of building in the chroot envirnment. It will be overwritten
in the install phase below.</para></note>
<screen><userinput remap="test">make check</userinput></screen>
<para>You may see some test failures. The Glibc test suite is
somewhat dependent on the host system. This is a list of the most common
issues seen for some versions of LFS:</para>
<itemizedlist>
<listitem>
<para><emphasis>misc/tst-ttyname</emphasis>
is known to fail in the LFS chroot environment.</para>
</listitem>
<!--
<listitem>
<para><emphasis>inet/tst-idna_name_classify</emphasis>
is known to fail in the LFS chroot environment.</para>
</listitem>
-->
<listitem>
<para><emphasis>posix/tst-getaddrinfo4</emphasis> and
<emphasis>posix/tst-getaddrinfo5</emphasis>
may fail on some architectures.</para>
</listitem>
<listitem>
<para>The <emphasis>nss/tst-nss-files-hosts-multi</emphasis>
test may fail for reasons that have not been determined.</para>
</listitem>
<listitem>
<para>The <emphasis>rt/tst-cputimer{1,2,3}</emphasis> tests depend on
the host system kernel. Kernels 4.14.91&ndash;4.14.96,
4.19.13&ndash;4.19.18, and 4.20.0&ndash;4.20.5 are known to
cause these tests to fail.
</para>
</listitem>
<listitem>
<para>The math tests sometimes fail when running on
systems where the CPU is not a relatively new Intel or
AMD processor.</para>
</listitem>
<!--
<listitem>
<para>The
<emphasis>nptl/tst-thread-affinity-{pthread,pthread2,sched}</emphasis>
tests may fail for reasons that have not been determined. </para>
</listitem>
<listitem>
<para>Other tests known to fail on some architectures are
malloc/tst-malloc-usable and nptl/tst-cleanupx4. </para>
</listitem>
-->
</itemizedlist>
<para>Though it is a harmless message, the install stage of Glibc will
complain about the absence of <filename>/etc/ld.so.conf</filename>.
Prevent this warning with:</para>
<screen><userinput remap="install">touch /etc/ld.so.conf</userinput></screen>
<para>Fix the generated Makefile to skip an unneeded sanity check
that fails in the LFS partial environment:
</para>
<screen><userinput remap="install">sed '/test-installation/s@$(PERL)@echo not running@' -i ../Makefile</userinput></screen>
<para>Install the package:</para>
<screen><userinput remap="install">make install</userinput></screen>
<para>Install the configuration file and runtime directory for
<command>nscd</command>:</para>
<screen><userinput remap="install">cp -v ../nscd/nscd.conf /etc/nscd.conf
mkdir -pv /var/cache/nscd</userinput></screen>
<para revision="systemd">Install the systemd support files for
<command>nscd</command>:</para>
<screen revision="systemd"><userinput remap="install">install -v -Dm644 ../nscd/nscd.tmpfiles /usr/lib/tmpfiles.d/nscd.conf
install -v -Dm644 ../nscd/nscd.service /lib/systemd/system/nscd.service</userinput></screen>
<para>Next, install the locales that can make the system respond in a
different language. None of the locales are required, but if some of them
are missing, the test suites of future packages would skip important
testcases.</para>
<para>Individual locales can be installed using the
<command>localedef</command> program. E.g., the first
<command>localedef</command> command below combines the
<filename>/usr/share/i18n/locales/cs_CZ</filename>
charset-independent locale definition with the
<filename>/usr/share/i18n/charmaps/UTF-8.gz</filename>
charmap definition and appends the result to the
<filename>/usr/lib/locale/locale-archive</filename> file.
The following instructions will install the minimum set of
locales necessary for the optimal coverage of tests:</para>
<screen role="nodump"><userinput remap="locale-test">mkdir -pv /usr/lib/locale
localedef -i cs_CZ -f UTF-8 cs_CZ.UTF-8
localedef -i de_DE -f ISO-8859-1 de_DE
localedef -i de_DE@euro -f ISO-8859-15 de_DE@euro
localedef -i de_DE -f UTF-8 de_DE.UTF-8
localedef -i en_GB -f UTF-8 en_GB.UTF-8
localedef -i en_HK -f ISO-8859-1 en_HK
localedef -i en_PH -f ISO-8859-1 en_PH
localedef -i en_US -f ISO-8859-1 en_US
localedef -i en_US -f UTF-8 en_US.UTF-8
localedef -i es_MX -f ISO-8859-1 es_MX
localedef -i fa_IR -f UTF-8 fa_IR
localedef -i fr_FR -f ISO-8859-1 fr_FR
localedef -i fr_FR@euro -f ISO-8859-15 fr_FR@euro
localedef -i fr_FR -f UTF-8 fr_FR.UTF-8
localedef -i it_IT -f ISO-8859-1 it_IT
localedef -i it_IT -f UTF-8 it_IT.UTF-8
localedef -i ja_JP -f EUC-JP ja_JP
localedef -i ru_RU -f KOI8-R ru_RU.KOI8-R
localedef -i ru_RU -f UTF-8 ru_RU.UTF-8
localedef -i tr_TR -f UTF-8 tr_TR.UTF-8
localedef -i zh_CN -f GB18030 zh_CN.GB18030</userinput></screen>
<para>In addition, install the locale for your own country, language and
character set.</para>
<para>Alternatively, install all locales listed in the
<filename>glibc-&glibc-version;/localedata/SUPPORTED</filename> file
(it includes every locale listed above and many more) at once with the
following time-consuming command:</para>
<screen><userinput remap="locale-full">make localedata/install-locales</userinput></screen>
<para>Then use the <command>localedef</command> command to create and
install locales not listed in the
<filename>glibc-&glibc-version;/localedata/SUPPORTED</filename> file
in the unlikely case you need them.</para>
<note><para>Glibc now uses libidn2 when resolving internationalized
domain names. This is a run time dependency. If this capability
is needed, the instructions for installing libidn2 are in the
<ulink url="&blfs-book;general/libidn2.html">BLFS libidn2 page</ulink>.
</para></note>
</sect2>
<sect2 id="conf-glibc" role="configuration">
<title>Configuring Glibc</title>
<indexterm zone="conf-glibc">
<primary sortas="e-/etc/nsswitch.conf">/etc/nsswitch.conf</primary>
</indexterm>
<indexterm zone="conf-glibc">
<primary sortas="e-/etc/localtime">/etc/localtime</primary>
</indexterm>
<sect3>
<title>Adding nsswitch.conf</title>
<para>The <filename>/etc/nsswitch.conf</filename> file needs to be created
because the Glibc defaults do not work well in a networked environment.
</para>
<para>Create a new file <filename>/etc/nsswitch.conf</filename> by running the
following:</para>
<screen><userinput>cat &gt; /etc/nsswitch.conf &lt;&lt; "EOF"
<literal># Begin /etc/nsswitch.conf
passwd: files
group: files
shadow: files
hosts: files dns
networks: files
protocols: files
services: files
ethers: files
rpc: files
# End /etc/nsswitch.conf</literal>
EOF</userinput></screen>
</sect3>
<sect3>
<title>Adding time zone data</title>
<para>Install and set up the time zone data with the following:</para>
<screen><userinput>tar -xf ../../tzdata&tzdata-version;.tar.gz
ZONEINFO=/usr/share/zoneinfo
mkdir -pv $ZONEINFO/{posix,right}
for tz in etcetera southamerica northamerica europe africa antarctica \
asia australasia backward pacificnew systemv; do
zic -L /dev/null -d $ZONEINFO ${tz}
zic -L /dev/null -d $ZONEINFO/posix ${tz}
zic -L leapseconds -d $ZONEINFO/right ${tz}
done
cp -v zone.tab zone1970.tab iso3166.tab $ZONEINFO
zic -d $ZONEINFO -p America/New_York
unset ZONEINFO</userinput></screen>
<variablelist>
<title>The meaning of the zic commands:</title>
<varlistentry>
<term><parameter>zic -L /dev/null ...</parameter></term>
<listitem>
<para>This creates posix time zones, without any leap seconds. It is
conventional to put these in both
<filename class="directory">zoneinfo</filename> and
<filename class="directory">zoneinfo/posix</filename>. It is
necessary to put the POSIX time zones in
<filename class="directory">zoneinfo</filename>, otherwise various
test-suites will report errors. On an embedded system, where space is
tight and you do not intend to ever update the time zones, you could save
1.9MB by not using the <filename class="directory">posix</filename>
directory, but some applications or test-suites might produce some
failures.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>zic -L leapseconds ...</parameter></term>
<listitem>
<para>This creates right time zones, including leap seconds. On an
embedded system, where space is tight and you do not intend to
ever update the time zones, or care about the correct time, you could
save 1.9MB by omitting the <filename class="directory">right</filename>
directory.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>zic ... -p ...</parameter></term>
<listitem>
<para>This creates the <filename>posixrules</filename> file. We use
New York because POSIX requires the daylight savings time rules
to be in accordance with US rules.</para>
</listitem>
</varlistentry>
</variablelist>
<para>One way to determine the local time zone is to run the following
script:</para>
<screen role="nodump"><userinput>tzselect</userinput></screen>
<para>After answering a few questions about the location, the script will
output the name of the time zone (e.g.,
<emphasis>America/Edmonton</emphasis>). There are also some other possible
time zones listed in <filename
class='directory'>/usr/share/zoneinfo</filename> such as
<emphasis>Canada/Eastern</emphasis> or <emphasis>EST5EDT</emphasis> that
are not identified by the script but can be used.</para>
<para>Then create the <filename>/etc/localtime</filename> file by
running:</para>
<screen revision="sysv"><userinput>cp -v /usr/share/zoneinfo/<replaceable>&lt;xxx&gt;</replaceable> /etc/localtime</userinput></screen>
<screen revision="systemd"><userinput>ln -sfv /usr/share/zoneinfo/<replaceable>&lt;xxx&gt;</replaceable> /etc/localtime</userinput></screen>
<para>Replace <replaceable>&lt;xxx&gt;</replaceable> with the name of the
time zone selected (e.g., Canada/Eastern).</para>
</sect3>
<sect3 id="conf-ld" role="configuration">
<title>Configuring the Dynamic Loader</title>
<indexterm zone="conf-ld">
<primary sortas="e-/etc/ld.so.conf">/etc/ld.so.conf</primary>
</indexterm>
<para>By default, the dynamic loader (<filename
class="libraryfile">/lib/ld-linux.so.2</filename>) searches through
<filename class="directory">/lib</filename> and <filename
class="directory">/usr/lib</filename> for dynamic libraries that are
needed by programs as they are run. However, if there are libraries in
directories other than <filename class="directory">/lib</filename> and
<filename class="directory">/usr/lib</filename>, these need to be added
to the <filename>/etc/ld.so.conf</filename> file in order for the
dynamic loader to find them. Two directories that are commonly known
to contain additional libraries are <filename
class="directory">/usr/local/lib</filename> and <filename
class="directory">/opt/lib</filename>, so add those directories to the
dynamic loader's search path.</para>
<para>Create a new file <filename>/etc/ld.so.conf</filename> by running the
following:</para>
<screen><userinput>cat &gt; /etc/ld.so.conf &lt;&lt; "EOF"
<literal># Begin /etc/ld.so.conf
/usr/local/lib
/opt/lib
</literal>
EOF</userinput></screen>
<para>If desired, the dynamic loader can also search a directory and
include the contents of files found there. Generally the files in
this include directory are one line specifying the desired library path.
To add this capability run the following commands:</para>
<screen role="nodump"><userinput>cat &gt;&gt; /etc/ld.so.conf &lt;&lt; "EOF"
<literal># Add an include directory
include /etc/ld.so.conf.d/*.conf
</literal>
EOF
mkdir -pv /etc/ld.so.conf.d</userinput></screen>
</sect3>
</sect2>
<sect2 id="contents-glibc" role="content">
<title>Contents of Glibc</title>
<segmentedlist>
<segtitle>Installed programs</segtitle>
<segtitle>Installed libraries</segtitle>
<segtitle>Installed directories</segtitle>
<seglistitem>
<seg>catchsegv, gencat, getconf, getent, iconv, iconvconfig, ldconfig,
ldd, lddlibc4, locale, localedef, makedb, mtrace, nscd,
pldd, sln, sotruss, sprof, tzselect, xtrace,
zdump, and zic</seg>
<seg>ld-&glibc-version;.so, libBrokenLocale.{a,so}, libSegFault.so, libanl.{a,so},
libc.{a,so}, libc_nonshared.a, libcidn.so,
libcrypt.{a,so}, libdl.{a,so}, libg.a, libieee.a, libm.{a,so},
libmcheck.a, libmemusage.so, libnsl.{a,so}, libnss_compat.so,
libnss_dns.so, libnss_files.so, libnss_hesiod.so, libnss_nis.so,
libnss_nisplus.so, libpthread.{a,so},
libpthread_nonshared.a, libresolv.{a,so}, librpcsvc.a, librt.{a,so},
libthread_db.so, and libutil.{a,so}</seg>
<seg>/usr/include/arpa, /usr/include/bits, /usr/include/gnu,
/usr/include/net, /usr/include/netash, /usr/include/netatalk,
/usr/include/netax25, /usr/include/neteconet, /usr/include/netinet,
/usr/include/netipx, /usr/include/netiucv, /usr/include/netpacket,
/usr/include/netrom, /usr/include/netrose, /usr/include/nfs,
/usr/include/protocols, /usr/include/rpc, /usr/include/rpcsvc,
/usr/include/sys, /usr/lib/audit, /usr/lib/gconv, /usr/lib/locale,
/usr/libexec/getconf, /usr/share/i18n, /usr/share/zoneinfo,
/var/cache/nscd, and /var/lib/nss_db</seg>
</seglistitem>
</segmentedlist>
<variablelist>
<bridgehead renderas="sect3">Short Descriptions</bridgehead>
<?dbfo list-presentation="list"?>
<?dbhtml list-presentation="table"?>
<varlistentry id="catchsegv">
<term><command>catchsegv</command></term>
<listitem>
<para>Can be used to create a stack trace when a program
terminates with a segmentation fault</para>
<indexterm zone="ch-system-glibc catchsegv">
<primary sortas="b-catchsegv">catchsegv</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="gencat">
<term><command>gencat</command></term>
<listitem>
<para>Generates message catalogues</para>
<indexterm zone="ch-system-glibc gencat">
<primary sortas="b-gencat">gencat</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="getconf">
<term><command>getconf</command></term>
<listitem>
<para>Displays the system configuration values for file system
specific variables</para>
<indexterm zone="ch-system-glibc getconf">
<primary sortas="b-getconf">getconf</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="getent">
<term><command>getent</command></term>
<listitem>
<para>Gets entries from an administrative database</para>
<indexterm zone="ch-system-glibc getent">
<primary sortas="b-getent">getent</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="iconv">
<term><command>iconv</command></term>
<listitem>
<para>Performs character set conversion</para>
<indexterm zone="ch-system-glibc iconv">
<primary sortas="b-iconv">iconv</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="iconvconfig">
<term><command>iconvconfig</command></term>
<listitem>
<para>Creates fastloading <command>iconv</command> module configuration
files</para>
<indexterm zone="ch-system-glibc iconvconfig">
<primary sortas="b-iconvconfig">iconvconfig</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="ldconfig">
<term><command>ldconfig</command></term>
<listitem>
<para>Configures the dynamic linker runtime bindings</para>
<indexterm zone="ch-system-glibc ldconfig">
<primary sortas="b-ldconfig">ldconfig</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="ldd">
<term><command>ldd</command></term>
<listitem>
<para>Reports which shared libraries are required
by each given program or shared library</para>
<indexterm zone="ch-system-glibc ldd">
<primary sortas="b-ldd">ldd</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="lddlibc4">
<term><command>lddlibc4</command></term>
<listitem>
<para>Assists <command>ldd</command> with object files</para>
<indexterm zone="ch-system-glibc lddlibc4">
<primary sortas="b-lddlibc4">lddlibc4</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="locale">
<term><command>locale</command></term>
<listitem>
<para>Prints various information about the current locale</para>
<indexterm zone="ch-system-glibc locale">
<primary sortas="b-locale">locale</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="localedef">
<term><command>localedef</command></term>
<listitem>
<para>Compiles locale specifications</para>
<indexterm zone="ch-system-glibc localedef">
<primary sortas="b-localedef">localedef</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="makedb">
<term><command>makedb</command></term>
<listitem>
<para>Creates a simple database from textual input</para>
<indexterm zone="ch-system-glibc makedb">
<primary sortas="b-makedb">makedb</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="mtrace">
<term><command>mtrace</command></term>
<listitem>
<para>Reads and interprets a memory trace file and displays a summary
in human-readable format</para>
<indexterm zone="ch-system-glibc mtrace">
<primary sortas="b-mtrace">mtrace</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="nscd">
<term><command>nscd</command></term>
<listitem>
<para>A daemon that provides a cache for the most common name
service requests</para>
<indexterm zone="ch-system-glibc nscd">
<primary sortas="b-nscd">nscd</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="pldd">
<term><command>pldd</command></term>
<listitem>
<para>Lists dynamic shared objects used by running processes</para>
<indexterm zone="ch-system-glibc pldd">
<primary sortas="b-pldd">pldd</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="sln">
<term><command>sln</command></term>
<listitem>
<para>A statically linked <command>ln</command> program</para>
<indexterm zone="ch-system-glibc sln">
<primary sortas="b-sln">sln</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="sotruss">
<term><command>sotruss</command></term>
<listitem>
<para>Traces shared library procedure calls of a specified command</para>
<indexterm zone="ch-system-glibc sotruss">
<primary sortas="b-sotruss">sotruss</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="sprof">
<term><command>sprof</command></term>
<listitem>
<para>Reads and displays shared object profiling data</para>
<indexterm zone="ch-system-glibc sprof">
<primary sortas="b-sprof">sprof</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="tzselect">
<term><command>tzselect</command></term>
<listitem>
<para>Asks the user about the location of the system and reports
the corresponding time zone description</para>
<indexterm zone="ch-system-glibc tzselect">
<primary sortas="b-tzselect">tzselect</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="xtrace">
<term><command>xtrace</command></term>
<listitem>
<para>Traces the execution of a program by printing the currently
executed function</para>
<indexterm zone="ch-system-glibc xtrace">
<primary sortas="b-xtrace">xtrace</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="zdump">
<term><command>zdump</command></term>
<listitem>
<para>The time zone dumper</para>
<indexterm zone="ch-system-glibc zdump">
<primary sortas="b-zdump">zdump</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="zic">
<term><command>zic</command></term>
<listitem>
<para>The time zone compiler</para>
<indexterm zone="ch-system-glibc zic">
<primary sortas="b-zic">zic</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="ld.so">
<term><filename class="libraryfile">ld-&glibc-version;.so</filename></term>
<listitem>
<para>The helper program for shared library executables</para>
<indexterm zone="ch-system-glibc ld.so">
<primary sortas="c-ld.so">ld-&glibc-version;.so</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libBrokenLocale">
<term><filename class="libraryfile">libBrokenLocale</filename></term>
<listitem>
<para>Used internally by Glibc as a gross hack to get broken programs
(e.g., some Motif applications) running. See comments in
<filename>glibc-&glibc-version;/locale/broken_cur_max.c</filename>
for more information</para>
<indexterm zone="ch-system-glibc libBrokenLocale">
<primary sortas="c-libBrokenLocale">libBrokenLocale</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libSegFault">
<term><filename class="libraryfile">libSegFault</filename></term>
<listitem>
<para>The segmentation fault signal handler, used by
<command>catchsegv</command></para>
<indexterm zone="ch-system-glibc libSegFault">
<primary sortas="c-libSegFault">libSegFault</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libanl">
<term><filename class="libraryfile">libanl</filename></term>
<listitem>
<para>An asynchronous name lookup library</para>
<indexterm zone="ch-system-glibc libanl">
<primary sortas="c-libanl">libanl</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libc">
<term><filename class="libraryfile">libc</filename></term>
<listitem>
<para>The main C library</para>
<indexterm zone="ch-system-glibc libc">
<primary sortas="c-libc">libc</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libcidn">
<term><filename class="libraryfile">libcidn</filename></term>
<listitem>
<para>Used internally by Glibc for handling internationalized domain
names in the <function>getaddrinfo()</function> function</para>
<indexterm zone="ch-system-glibc libcidn">
<primary sortas="c-libcidn">libcidn</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libcrypt">
<term><filename class="libraryfile">libcrypt</filename></term>
<listitem>
<para>The cryptography library</para>
<indexterm zone="ch-system-glibc libcrypt">
<primary sortas="c-libcrypt">libcrypt</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libdl">
<term><filename class="libraryfile">libdl</filename></term>
<listitem>
<para>The dynamic linking interface library</para>
<indexterm zone="ch-system-glibc libdl">
<primary sortas="c-libdl">libdl</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libg">
<term><filename class="libraryfile">libg</filename></term>
<listitem>
<para>Dummy library containing no functions. Previously was a runtime
library for <command>g++</command></para>
<indexterm zone="ch-system-glibc libg">
<primary sortas="c-libg">libg</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libieee">
<term><filename class="libraryfile">libieee</filename></term>
<listitem>
<para>Linking in this module forces error handling rules for math
functions as defined by the Institute of Electrical and Electronic
Engineers (IEEE). The default is POSIX.1 error handling</para>
<indexterm zone="ch-system-glibc libieee">
<primary sortas="c-libieee">libieee</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libm">
<term><filename class="libraryfile">libm</filename></term>
<listitem>
<para>The mathematical library</para>
<indexterm zone="ch-system-glibc libm">
<primary sortas="c-libm">libm</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libmcheck">
<term><filename class="libraryfile">libmcheck</filename></term>
<listitem>
<para>Turns on memory allocation checking when linked to</para>
<indexterm zone="ch-system-glibc libmcheck">
<primary sortas="c-libmcheck">libmcheck</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libmemusage">
<term><filename class="libraryfile">libmemusage</filename></term>
<listitem>
<para>Used by <command>memusage</command> to help collect
information about the memory usage of a program</para>
<indexterm zone="ch-system-glibc libmemusage">
<primary sortas="c-libmemusage">libmemusage</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libnsl">
<term><filename class="libraryfile">libnsl</filename></term>
<listitem>
<para>The network services library</para>
<indexterm zone="ch-system-glibc libnsl">
<primary sortas="c-libnsl">libnsl</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libnss">
<term><filename class="libraryfile">libnss</filename></term>
<listitem>
<para>The Name Service Switch libraries, containing functions for
resolving host names, user names, group names, aliases, services,
protocols, etc.</para>
<indexterm zone="ch-system-glibc libnss">
<primary sortas="c-libnss">libnss</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libpthread">
<term><filename class="libraryfile">libpthread</filename></term>
<listitem>
<para>The POSIX threads library</para>
<indexterm zone="ch-system-glibc libpthread">
<primary sortas="c-libpthread">libpthread</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libresolv">
<term><filename class="libraryfile">libresolv</filename></term>
<listitem>
<para>Contains functions for creating, sending, and interpreting
packets to the Internet domain name servers</para>
<indexterm zone="ch-system-glibc libresolv">
<primary sortas="c-libresolv">libresolv</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="librpcsvc">
<term><filename class="libraryfile">librpcsvc</filename></term>
<listitem>
<para>Contains functions providing miscellaneous RPC services</para>
<indexterm zone="ch-system-glibc librpcsvc">
<primary sortas="c-librpcsvc">librpcsvc</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="librt">
<term><filename class="libraryfile">librt</filename></term>
<listitem>
<para>Contains functions providing most of the interfaces specified
by the POSIX.1b Realtime Extension</para>
<indexterm zone="ch-system-glibc librt">
<primary sortas="c-librt">librt</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libthread_db">
<term><filename class="libraryfile">libthread_db</filename></term>
<listitem>
<para>Contains functions useful for building debuggers for
multi-threaded programs</para>
<indexterm zone="ch-system-glibc libthread_db">
<primary sortas="c-libthread_db">libthread_db</primary>
</indexterm>
</listitem>
</varlistentry>
<varlistentry id="libutil">
<term><filename class="libraryfile">libutil</filename></term>
<listitem>
<para>Contains code for <quote>standard</quote> functions used in
many different Unix utilities</para>
<indexterm zone="ch-system-glibc libutil">
<primary sortas="c-libutil">libutil</primary>
</indexterm>
</listitem>
</varlistentry>
</variablelist>
</sect2>
</sect1>