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

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

<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 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 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>

<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></para>

<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 it can be seen right away what's being searched and a you
don't have to remember the default search paths if you don't want to.</para>

</sect2>