lfs-book-zh_CN/chapter06/config-ldso.xml

<sect2>
<title>Configuring Dynamic Loader</title>

<para>
By default the dynamic loader searches a few default paths for dynamic
libraries, so there normally isn't a need for the
<filename>/etc/ld.so.conf</filename> file unless you have extra
directories in which you want the system to search for paths. The
<filename class="directory">/usr/local/lib</filename> directory isn't
searched through for dynamic libraries by default, so we want to add
this path so when you install software you won't be suprised by them not
running for some reason.
</para>

<para>
Create a new file <filename>/etc/ld.so.conf</filename> by running the
following:
</para>

<literallayout>

<userinput>cat &gt; /etc/ld.so.conf &lt;&lt; "EOF"</userinput>
# Begin /etc/ld.so.conf

/lib
/usr/lib
/usr/local/lib

# End /etc/ld.so.conf
<userinput>EOF</userinput>

</literallayout>

<para>
Although it's not necessary to add the 
<filename class="directory">/lib</filename> and 
<filename class="directory">/usr/lib</filename> directories it doesn't 
hurt. This way you see right away what's being searched and don't have 
to remeber the default search paths if you don't want to.
</para>

</sect2>