lfs-book/chapter06/glibc-exp.xml

<sect2>
<title>Command explanations</title>

<para><userinput>touch /etc/ld.so.conf:</userinput> One of the final steps
of the Glibc installation is running ldconfig to update the dynamic loader
cache. If this file doesn't exist, the installation will abort with an error
that it can't read the file, so we simply create an empty file (the empty
file will have Glibc default to using /lib and /usr/lib which is fine).</para>

<para><userinput>sed 's%\$(PERL)%/usr/bin/perl%' 
malloc/Makefile.backup &gt; malloc/Makefile:</userinput> This sed command
searches through <filename>malloc/Makefile.backup</filename> and
converts all occurrences of <filename>$(PERL)</filename> to
<filename>/usr/bin/perl</filename>. The output is then written to the
original <filename>malloc/Makefile.in</filename> which is used during
configuration. This is done because Glibc can't autodetect perl since
it hasn't been installed yet.</para>

<para><userinput>sed 's/root/0' login/Makefile.backup &gt;
login/Makefile:</userinput> This sed command replaces all occurrences of
<filename>root</filename> in <filename>login/Makefile.backup</filename>
with 0. This is because we don't have glibc on the LFS system yet, so
usernames can't be resolved to their user id's. Therefore, we replace
the username root with user id 0.</para>

<para><userinput>--enable-add-ons:</userinput> This enables the add-on that
we install with Glibc: linuxthreads</para>

<para><userinput>--libexecdir=/usr/bin:</userinput> This will cause the
pt_chown program to be installed in the /usr/bin directory.</para>

<para><userinput>echo "cross-compiling = no" &gt; configparms:</userinput>
We do this because we are only building for our own system. Cross-compiling
is used, for instance, to build a package for an Apple Power PC on an
Intel system. The reason Glibc thinks we're cross-compiling is that it
can't compile a test program to determine this, so it automatically defaults
to a cross-compiler. Compiling the test program fails because Glibc hasn't
been installed yet.</para>

<para><userinput>exec /bin/bash:</userinput>This command will
start a new bash shell which will replace the current shell. This is 
done to get rid of the "I have no name!" message in the command 
prompt, which was caused by bash's inability to resolve a userid to 
a username (which in turn was caused by the missing Glibc 
installation).</para>

</sect2>