docs/172692: [PATCH] Bring parts of the rc scripting guides up to date

[Michael Telahun Makonnen]

Some minor nits:

@@ -479,7 +479,7 @@
        <important>
         <para>The names of all &man.rc.conf.5; variables used
           exclusively by our script <emphasis>must</emphasis>
-       have the same prefix: <envar>${name}</envar>.  For
+        have the same prefix: <envar>${name}_</envar>.  For
         example: <envar>dummy_mode</envar>,
         <envar>dummy_state_file</envar>, and so on.</para>
        </important>

You should add the same correction to the very next sentence, which reads:

Note: While it is possible to use a shorter name internally, e.g.,  just 
msg, adding the unique prefix ${name} to all global names introduced by 
our script will save us from possible collisions with the rc.subr(8) 
namespace.


@@ -491,15 +491,6 @@
             our script will save us from possible
           collisions with the &man.rc.subr.8; namespace.</para>

-   <para>As long as an &man.rc.conf.5; variable and its
-          internal equivalent are the same, we can use a more
-           compact expression to set the default value:</para>
-
-         <programlisting>: ${dummy_msg:="Nothing 
started."}</programlisting>
-
-   <para>The current style is to use the more verbose form
-           though.</para>
-

Not sure why you felt this paragraph needed to be removed.

@@ -512,7 +503,11 @@

        <callout arearefs="rcng-confdummy-msg">
     <para>Here we use <envar>dummy_msg</envar> to actually
-        control our script, i.e., to emit a variable message.</para>
+    control our script, i.e., to emit a variable message.
+         Use of a shell function is overkill here, since it only
+       runs a single command; an equally valid alternative is:</para>
+
+      <programlisting>start_cmd="echo \"$dummy_msg\""</programlisting>

While you are technically correct, I think you misunderstood the 
writer's intent, which was to show how an rc.conf(8) variable can be 
used in a subroutine to control the behavior of the command.  I agree 
that the example isn't a very good one (in that it doesn't depict a 
valid use case), but I think the "spirit" is correct.  Maybe you can 
suggest a better example?

Cheers,
Mike.