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<sect1 id="ch-system-glibc" xreflabel="Glibc">

<title>Glibc-&glibc-version;</title>

<?dbhtml filename="glibc.html"?>

<indexterm zone="ch-system-glibc"><primary sortas="a-Glibc">Glibc</primary></indexterm>

<para>The Glibc package contains the main C library. This library provides all

the basic routines for allocating memory, searching directories, opening and

closing files, reading and writing them, string handling, pattern matching,

arithmetic, and so on.</para>

<screen>&buildtime; 12.3 SBU

&diskspace; 784 MB</screen>

<para>Glibc installation depends on: Bash, Binutils, Coreutils, Diffutils,

Gawk, GCC, Gettext, Grep, Make, Perl, Sed, Texinfo.</para>

<sect2>

<title>Installation of Glibc</title>

<para>The Glibc build system is very well self-contained and will install

perfectly, even though our compiler specs file and linker are still pointing

at <filename>/tools</filename>. We cannot adjust the specs and linker before

the Glibc install, because the Glibc autoconf tests would then give bogus

results and thus defeat our goal of achieving a clean build.</para>

<para>Before starting to build Glibc, remember to unset any environment

variables that override the default optimization flags.</para>

<para>The Glibc documentation recommends building Glibc outside of the source

directory in a dedicated build directory:</para>

<screen><userinput>mkdir ../glibc-build

cd ../glibc-build</userinput></screen>

<para>Now prepare Glibc for compilation:</para>

<screen><userinput>../glibc-&glibc-version;/configure --prefix=/usr \

    --disable-profile --enable-add-ons=linuxthreads \

    --libexecdir=/usr/lib --with-headers=/usr/include \

    --without-cvs</userinput></screen>

<para>The meaning of the new configure options:</para>

<itemizedlist>

<listitem><para><userinput>--libexecdir=/usr/lib</userinput>: This changes the

location of the <filename>pt_chown</filename> program from its default of

<filename class="directory">/usr/libexec</filename> to

<filename class="directory">/usr/lib</filename>. The use of

<emphasis>libexec</emphasis> is considered not to be FHS-compliant because the

FHS doesn't even mention it.</para></listitem>

<listitem><para><userinput>--with-headers=/usr/include</userinput>: This

ensures that the kernel headers in <filename>/usr/include</filename> are used

for this build. If you don't pass this switch then the headers from

<filename>/tools/include</filename> are used which of course is not ideal

(although they should be identical). Using this switch has the advantage

that you will be informed immediately should you have forgotten to install the

kernel headers into <filename>/usr/include</filename>.</para></listitem>

</itemizedlist>

<para>Compile the package:</para>

<screen><userinput>make</userinput></screen>

<important><para>The test suite for Glibc in this section is considered

<emphasis>critical</emphasis>. Our advice is to not skip it under any

circumstance.</para></important>

<para>Test the results:</para>

<screen><userinput>make check</userinput></screen>

<para>The test suite notes from <xref linkend="ch-tools-glibc"/> are still very much

appropriate here. Be sure to refer back there should you have any doubts.</para>

<para>Though it is a harmless message, the install stage of Glibc will

complain about the absence of <filename>/etc/ld.so.conf</filename>. Fix this

annoying little warning with:</para>

<screen><userinput>touch /etc/ld.so.conf</userinput></screen>

<para>And install the package:</para>

<screen><userinput>make install</userinput></screen>

<para>The locales that can make your system respond in a different language

weren't installed by the above command. Do it with this:</para>

<screen><userinput>make localedata/install-locales</userinput></screen>

<para>An alternative to running the previous command is to install only those

locales which you need or want. This can be achieved by using the

<command>localedef</command> command. Information on this can be found in

the <filename>INSTALL</filename> file in the Glibc source. However, there are

a number of locales that are essential for the tests of future packages to

pass, in particular, the <emphasis>libstdc++</emphasis> tests from GCC. The

following instructions, instead of the install-locales target above, will

install the minimum set of locales necessary for the tests to run

successfully:</para>

<screen><userinput>mkdir -p /usr/lib/locale

localedef -i de_DE -f ISO-8859-1 de_DE

localedef -i de_DE@euro -f ISO-8859-15 de_DE@euro

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 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 it_IT -f ISO-8859-1 it_IT

localedef -i ja_JP -f EUC-JP ja_JP</userinput></screen>

<para>Finally, build the linuxthreads man pages:</para>

<screen><userinput>make -C ../glibc-&glibc-version;/linuxthreads/man</userinput></screen>

<para>And install these pages:</para>

<screen><userinput>make -C ../glibc-&glibc-version;/linuxthreads/man install</userinput></screen>

</sect2>

<sect2 id="conf-glibc"><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>

<para>We need to create the <filename>/etc/nsswitch.conf</filename> file,

because, although Glibc provides defaults when this file is missing or corrupt,

the Glibc defaults don't work well with networking. Also, our time zone needs

to be set up.</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"</userinput>

# 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

<userinput>EOF</userinput></screen>

<para>To find out what time zone you're in, run the following script:</para>

<screen><userinput>tzselect</userinput></screen>

<para>When you've answered a few questions about your location, the script will

output the name of your time zone, something like <emphasis>EST5EDT</emphasis>

or <emphasis>Canada/Eastern</emphasis>. Then create the

<filename>/etc/localtime</filename> file by running:</para>

<screen><userinput>cp --remove-destination /usr/share/zoneinfo/Canada/Eastern /etc/localtime</userinput></screen>

<para>The meaning of the option:</para>

<itemizedlist>

<listitem><para><userinput>--remove-destination</userinput>: This is needed to

force removal of the already existing symbolic link. The reason why we copy

instead of symlink is to cover the situation where <filename>/usr</filename> is

on a separate partition. This could matter, for example, when booted into single

user mode.</para></listitem>

</itemizedlist>

<para>Of course, instead of <emphasis>Canada/Eastern</emphasis>, fill in

the name of the time zone that the <command>tzselect</command> script

gave you.</para>

</sect2>

<sect2 id="conf-ld">

<title>Configuring 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>/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 when you run them. However, if there are libraries in

directories other than <filename class="directory">/lib</filename> and

<filename class="directory">/usr/lib</filename>, you need to add them to

the <filename>/etc/ld.so.conf</filename> file 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 we 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"</userinput>

# Begin /etc/ld.so.conf

/usr/local/lib

/opt/lib

# End /etc/ld.so.conf

<userinput>EOF</userinput></screen>

</sect2>

<sect2 id="contents-glibc"><title>Contents of Glibc</title>

<para><emphasis>Installed programs</emphasis>: catchsegv, gencat, getconf,

getent, glibcbug, iconv, iconvconfig, ldconfig, ldd, lddlibc4, locale,

localedef, mtrace, nscd, nscd_nischeck, pcprofiledump, pt_chown, rpcgen,

rpcinfo, sln, sprof, tzselect, xtrace, zdump and zic</para>

<para><emphasis>Installed libraries</emphasis>: ld.so, libBrokenLocale.[a,so],

libSegFault.so, libanl.[a,so], libbsd-compat.a, libc.[a,so], libc_nonshared.a,

libcrypt.[a,so], libdl.[a,so], libg.a, libieee.a, libm.[a,so], libmcheck.a,

libmemusage.so, libnsl.a, libnss_compat.so, libnss_dns.so, libnss_files.so,

libnss_hesiod.so, libnss_nis.so, libnss_nisplus.so, libpcprofile.so,

libpthread.[a,so], libresolv.[a,so], librpcsvc.a, librt.[a,so], libthread_db.so

and libutil.[a,so]</para>

</sect2>

<sect2><title>Short descriptions</title>

<indexterm zone="ch-system-glibc catchsegv"><primary sortas="b-catchsegv">catchsegv</primary></indexterm>

<para id="catchsegv"><command>catchsegv</command> can be used to create a stack trace

when a program terminates with a segmentation fault.</para>

<indexterm zone="ch-system-glibc gencat"><primary sortas="b-gencat">gencat</primary></indexterm>

<para id="gencat"><command>gencat</command> generates message catalogues.</para>

<indexterm zone="ch-system-glibc getconf"><primary sortas="b-getconf">getconf</primary></indexterm>

<para id="getconf"><command>getconf</command> displays the system configuration values

for file system specific variables.</para>

<indexterm zone="ch-system-glibc getent"><primary sortas="b-getent">getent</primary></indexterm>

<para id="getent"><command>getent</command> gets entries from an administrative

database.</para>

<indexterm zone="ch-system-glibc glibcbug"><primary sortas="b-glibcbug">glibcbug</primary></indexterm>

<para id="glibcbug"><command>glibcbug</command> creates a bug report and mails it to the

bug email address.</para>

<indexterm zone="ch-system-glibc iconv"><primary sortas="b-iconv">iconv</primary></indexterm>

<para id="iconv"><command>iconv</command> performs character set conversion.</para>

<indexterm zone="ch-system-glibc iconvconfig"><primary sortas="b-iconvconfig">iconvconfig</primary></indexterm>

<para id="iconvconfig"><command>iconvconfig</command> creates fastloading iconv module

configuration file.</para>

<indexterm zone="ch-system-glibc ldconfig"><primary sortas="b-ldconfig">ldconfig</primary></indexterm>

<para id="ldconfig"><command>ldconfig</command> configures the dynamic linker runtime

bindings.</para>

<indexterm zone="ch-system-glibc ldd"><primary sortas="b-ldd">ldd</primary></indexterm>

<para id="ldd"><command>ldd</command> reports which shared libraries are required

by each given program or shared library.</para>

<indexterm zone="ch-system-glibc lddlibc4"><primary sortas="b-lddlibc4">lddlibc4</primary></indexterm>

<para id="lddlibc4"><command>lddlibc4</command> assists ldd with object files.</para>

<indexterm zone="ch-system-glibc locale"><primary sortas="b-locale">locale</primary></indexterm>

<para id="locale"><command>locale</command> is a Perl program that tells the compiler

to enable or disable the use of POSIX locales for built-in operations.</para>

<indexterm zone="ch-system-glibc localedef"><primary sortas="b-localedef">localedef</primary></indexterm>

<para id="localedef"><command>localedef</command> compiles locale specifications.</para>

<indexterm zone="ch-system-glibc mtrace"><primary sortas="b-mtrace">mtrace</primary></indexterm>

<para id="mtrace"><command>mtrace</command>...</para>

<indexterm zone="ch-system-glibc nscd"><primary sortas="b-nscd">nscd</primary></indexterm>

<para id="nscd"><command>nscd</command> is a name service cache daemon providing a

cache for the most common name service requests.</para>

<indexterm zone="ch-system-glibc nscd_nischeck"><primary sortas="b-nscd_nischeck">nscd_nischeck</primary></indexterm>

<para id="nscd_nischeck"><command>nscd_nischeck</command> checks whether or not secure mode

is necessary for NIS+ lookup.</para>

<indexterm zone="ch-system-glibc pcprofiledump"><primary sortas="b-pcprofiledump">pcprofiledump</primary></indexterm>

<para id="pcprofiledump"><command>pcprofiledump</command> dumps information generated by

PC profiling.</para>

<indexterm zone="ch-system-glibc pt_chown"><primary sortas="b-pt_chown">pt_chown</primary></indexterm>

<para id="pt_chown"><command>pt_chown</command> is a helper program for grantpt to set

the owner, group and access permissions of a slave pseudo terminal.</para>

<indexterm zone="ch-system-glibc rpcgen"><primary sortas="b-rpcgen">rpcgen</primary></indexterm>

<para id="rpcgen"><command>rpcgen</command> generates C code to implement the

RPC protocol.</para>

<indexterm zone="ch-system-glibc rpcinfo"><primary sortas="b-rpcinfo">rpcinfo</primary></indexterm>

<para id="rpcinfo"><command>rpcinfo</command> makes an RPC call to an RPC server.</para>

<indexterm zone="ch-system-glibc sln"><primary sortas="b-sln">sln</primary></indexterm>

<para id="sln"><command>sln</command> is used to make symbolic links. The program

is statically linked, so it is useful for making symbolic links to dynamic

libraries if the dynamic linking system for some reason is nonfunctional.</para>

<indexterm zone="ch-system-glibc sprof"><primary sortas="b-sprof">sprof</primary></indexterm>

<para id="sprof"><command>sprof</command> reads and displays shared object profiling

data.</para>

<indexterm zone="ch-system-glibc tzselect"><primary sortas="b-tzselect">tzselect</primary></indexterm>

<para id="tzselect"><command>tzselect</command> asks the user about the location of the

system and reports the corresponding time zone description.</para>

<indexterm zone="ch-system-glibc xtrace"><primary sortas="b-xtrace">xtrace</primary></indexterm>

<para id="xtrace"><command>xtrace</command> traces the execution of a program by

printing the currently executed function.</para>

<indexterm zone="ch-system-glibc zdump"><primary sortas="b-zdump">zdump</primary></indexterm>

<para id="zdump"><command>zdump</command> is the time zone dumper.</para>

<indexterm zone="ch-system-glibc zic"><primary sortas="b-zic">zic</primary></indexterm>

<para id="zic"><command>zic</command> is the time zone compiler.</para>

<indexterm zone="ch-system-glibc ld.so"><primary sortas="c-ld.so">ld.so</primary></indexterm>

<para id="ld.so"><command>ld.so</command> is the helper program for shared library

executables.</para>

<indexterm zone="ch-system-glibc libBrokenLocale"><primary sortas="c-libBrokenLocale">libBrokenLocale</primary></indexterm>

<para id="libBrokenLocale"><command>libBrokenLocale</command> is used by programs, such as

Mozilla, to solve broken locales.</para>

<indexterm zone="ch-system-glibc libSegFault"><primary sortas="c-libSegFault">libSegFault</primary></indexterm>

<para id="libSegFault"><command>libSegFault</command> is a segmentation fault signal

handler. It tries to catch segfaults.</para>

<indexterm zone="ch-system-glibc libanl"><primary sortas="c-libanl">libanl</primary></indexterm>

<para id="libanl"><command>libanl</command> is an asynchronous name lookup

library.</para>

<indexterm zone="ch-system-glibc libbsd-compat"><primary sortas="c-libbsd-compat">libbsd-compat</primary></indexterm>

<para id="libbsd-compat"><command>libbsd-compat</command> provides the portability needed

in order to run certain BSD programs under Linux.</para>

<indexterm zone="ch-system-glibc libc"><primary sortas="c-libc">libc</primary></indexterm>

<para id="libc"><command>libc</command> is the main C library -- a collection of

commonly used functions.</para>

<indexterm zone="ch-system-glibc libcrypt"><primary sortas="c-libcrypt">libcrypt</primary></indexterm>

<para id="libcrypt"><command>libcrypt</command> is the cryptography library.</para>

<indexterm zone="ch-system-glibc libdl"><primary sortas="c-libdl">libdl</primary></indexterm>

<para id="libdl"><command>libdl</command> is the dynamic linking interface library.</para>

<indexterm zone="ch-system-glibc libg"><primary sortas="c-libg">libg</primary></indexterm>

<para id="libg"><command>libg</command> is a runtime library for g++.</para>

<indexterm zone="ch-system-glibc libieee"><primary sortas="c-libieee">libieee</primary></indexterm>

<para id="libieee"><command>libieee</command> is the IEEE floating point library.</para>

<indexterm zone="ch-system-glibc libm"><primary sortas="c-libm">libm</primary></indexterm>

<para id="libm"><command>libm</command> is the mathematical library.</para>

<indexterm zone="ch-system-glibc libmcheck"><primary sortas="c-libmcheck">libmcheck</primary></indexterm>

<para id="libmcheck"><command>libmcheck</command> contains code run at boot.</para>

<indexterm zone="ch-system-glibc libmemusage"><primary sortas="c-libmemusage">libmemusage</primary></indexterm>

<para id="libmemusage"><command>libmemusage</command> is used by memusage to help collect

information about the memory usage of a program.</para>

<indexterm zone="ch-system-glibc libnsl"><primary sortas="c-libnsl">libnsl</primary></indexterm>

<para id="libnsl"><command>libnsl</command> is the network services library.</para>

<indexterm zone="ch-system-glibc libnss"><primary sortas="c-libnss*">libnss*</primary></indexterm>

<para id="libnss"><command>libnss*</command> are the Name Service Switch libraries,

containing functions for resolving host names, user names, group names,

aliases, services, protocols,and the like.</para>

<indexterm zone="ch-system-glibc libpcprofile"><primary sortas="c-libpcprofile">libpcprofile</primary></indexterm>

<para id="libpcprofile"><command>libpcprofile</command> contains profiling functions used

to track the amount of CPU time spent in which source code lines.</para>

<indexterm zone="ch-system-glibc libpthread"><primary sortas="c-libpthread">libpthread</primary></indexterm>

<para id="libpthread"><command>libpthread</command> is the POSIX threads library.</para>

<indexterm zone="ch-system-glibc libresolv"><primary sortas="c-libresolv">libresolv</primary></indexterm>

<para id="libresolv"><command>libresolv</command> contains functions for creating,

sending, and interpreting packets to the Internet domain name servers.</para>

<indexterm zone="ch-system-glibc librpcsvc"><primary sortas="c-librpcsvc">librpcsvc</primary></indexterm>

<para id="librpcsvc"><command>librpcsvc</command>contains functions providing

miscellaneous RPC services.</para>

<indexterm zone="ch-system-glibc librt"><primary sortas="c-librt">librt</primary></indexterm>

<para id="librt"><command>librt</command> contains functions providing most of the

interfaces specified by the POSIX.1b Realtime Extension.</para>

<indexterm zone="ch-system-glibc libthread_db"><primary sortas="c-libthread_db">libthread_db</primary></indexterm>

<para id="libthread_db"><command>libthread_db</command> contains functions useful for

building debuggers for multi-threaded programs.</para>

<indexterm zone="ch-system-glibc libutil"><primary sortas="c-libutil">libutil</primary></indexterm>

<para id="libutil"><command>libutil</command> contains code for "standard" functions

used in many different Unix utilities.</para>

</sect2>

</sect1>