[wplug] Hierarchical runlevels?

[Vanco, Don]

>-----Original Message-----
>From: wplug-bounces+don.vanco=agilysys.com at wplug.org 
>[mailto:wplug-bounces+don.vanco=agilysys.com at wplug.org] 
>Sent: Tuesday, August 31, 2004 3:32 PM
>To: General user list
>Subject: Re: [wplug] Hierarchical runlevels?
>
>
>On Mon, Aug 30, 2004 at 07:43:11AM -0400, Vanco, Don wrote:
>> >I seem to have a vague recollection of such a thing...
>> 	Not really following you here - that's pretty much what Linux
>> does now.  Can you offer more detail on what you're trying to
>> understand?
>
>Well...  The Linux thing is clear to me; you specify, say, run 
>level 3, and
>get the services defined for run level 3 (rc3.d).
>
>I seem to have a recollection of a system within which, you 
>specify run level
>3, get services defined for run level 3, *and* services 
>defined for run levels
>4 and 5.  Similarly, if you specified run level 4, you would 
>get services
>defined for run level 4 *and* for run level 5. (Or something 
>like that.  It
>might be the lower numbers you get as extra.)
>
>I wasn't sure if I was remembering something I had really 
>seen, or if I was
>recalling a hallucination I'd experienced after inhaling too 
>many cat piss
>fumes...
	As far as I know - this is incorrect.

This is based on RH (and to some degree SuSE)
	All services are defined in scripts located in /etc/rc.d
	There are directories that represent each used runlevel, in
those directories are symbolic links to the scripts in /etc/rc.d, and
the name of the sym-link will start with a "K" or an "S" - indicating to
"S"tart this service when changing the runlevel and "K"ill this service
when changing the runlevel.  These numbers - S45xxxx, S67yyyyy,
K12zzzzz, K33eeee (the hierarchy, if you will) are determined by
information in the actual scripts in /etc/rc.d - as well as other
"hooks" that tie into commands like chkconfig and (on RH) "service"
(which is roughly equivalent to typing /etc/rc.d/"service" and getting
the modifier (start, stop, reload, etc) )
	So - if you are in runlevel 3 and init 6 (reboot) it will Kill
all services as required by /etc/rc3.d and Start all services as
required by /etc/rc6.d.  IIRC - there nothing but "K" scripts in
/etc/rc6.d..

	System-wide or "global" (or perhaps run-level independent)
services are generally started in some other portion of init - as in
rc.sysinit (as a rule reserved for system services) or rc.local (more
reserved for "user space" services / applications)

	But as far as I know there is no overlap between runlevels.
There may be similarities (particularly between 3 & 5) but it's nothing
more than that - booting to init level 3 will _never_ look at what's in
init level 5.

	This is as I understand it....

Don