Clarify SysV run levels.

Update the meaning of run level 2.

Add some clarifying remarks about run levels 0 and 6 (halt and reboot).

1 files changed, 17 insertions, 3 deletions

diff --git a/chapter09/usage.xml b/chapter09/usage.xml
index 6f8d7a03f..b249096c0 100644
--- a/chapter09/usage.xml
+++ b/chapter09/usage.xml
@@ -35,12 +35,22 @@
 
 <literallayout>0: halt the computer
 1: single-user mode
-2: multi-user mode without networking
+2: reserved for customization, otherwise does the same as 3
 3: multi-user mode with networking
 4: reserved for customization, otherwise does the same as 3
 5: same as 4, it is usually used for GUI login (like X's <command>xdm</command> or KDE's <command>kdm</command>)
 6: reboot the computer</literallayout>
 
+    <note>
+       <para>
+          Classically, run level 2 above was defined as 
+          "multi-user mode without networking", but this was only the case 
+          many years ago when multiple users could log into a system connected via
+          serial ports.  In today's environment it makes no sense and
+          we designate it now as "reserved".
+       </para>
+    </note>
+
   </sect2>
 
   <sect2 id="conf-sysvinit" role="configuration">
@@ -127,7 +137,7 @@ EOF</userinput></screen>
   <para>There are a number of directories under <filename
   class="directory">/etc/rc.d</filename> that look like <filename
   class="directory">rc?.d</filename> (where ? is the number of the run-level) and
-  <filename class="directory">rcsysinit.d</filename>, all containing a number of
+  <filename class="directory">rcS.d</filename>, all containing a number of
   symbolic links. Some begin with a <emphasis>K</emphasis>, the others begin with
   an <emphasis>S</emphasis>, and all of them have two numbers following the
   initial letter. The K means to stop (kill) a service and the S means to start a
@@ -155,7 +165,11 @@ EOF</userinput></screen>
   to be started. They will be called with the parameter
   <parameter>stop</parameter> to stop something. The logic behind this
   is that when a user is going to reboot or halt the system, nothing
-  needs to be started.  The system only needs to be stopped.</para>
+  needs to be started, but the order of shutdown needs to be controlled.
+  For these run levels, all <emphasis>K</emphasis> prefixed scripts will be 
+  run before any <emphasis>S</emphasis> prefixed scripts are run with the
+  <parameter>stop</parameter> parameter.
+  </para>
 
   <para>These are descriptions of what the arguments make the scripts
   do:</para>