[plug] Bootup services

[Andrew Pamment]

--- Mike Holland <myk at golden.wattle.id.au> wrote:
> That would seem logical, and Andrew said a similir
> thing, but a quick look
> in the /etc/rc* directories shows that is not the
> case at all. Rather
> than matched pairs of S & K, its either one or the
> other.

Ok, so, they don't look right? but go read the script
that runs these links. It's true. What do you think
might happen if you want to switch from multiuser mode
to single user mode? You don't want to unmount all
your file systems do you? Therefore, it would go into
your halt runlevel as something to be done. perhaps
you want to start an unmount script. you might call it
S99umount and stick it into your rc0.d so when you
halt, it does it.

Why couldn't you invent your own runlevels also?
perhaps you have a normal multiuser runlevel then
maybe a mission critical runlevel. so your happily
using normal multiuser runlevel, then suddenly the
sysadmin needs the machine for an important task.. you
get the message root switches to runlevel 9 in five
minutes - save your work now! then it kills all the
unnessiscary services, telnet daemons go down, ftp
servers stop, and the sysadmin now has his machine's
resources free to do mission critical applications
such as encode invader zim avi files into mpegs.

it doesn't have to have an exact mirror image, but i
guess it could have and rc0.d just be empty, so you
halt and it stops all services in runlevel4 directory
(or whatever)

>   The 'init' program actually knows nothing about
> these links and rc*
> directories - they are a messy hack (IMHO) added by
> SystemV. From init(8):

I don't use SystemV scripts at home, I use BSD ones,
but I was looking at converting them over over to
System V as I have a boring life and nothing better to
do. As I was looking into it, I noticed that it wasn't
init that knew about this. You see I downloaded a
slackware Sys-V type pre made set of scripts (look for
BsysV on freshmeat) It was a special SysV script. This
script went through the rcX.d directories, and ran the
links depending on the runlevel. It got the runlevel
from an environment variable ($runlevel) and got the
previous runlevel from another vairable. Aparrently
the kernel sets those vairables, though I won't
pretend to understand that.

But still, i don't expect SystemV engineers simply
thought oh, we'll use K and S, it'll make us look
intelligent by dazzling all our users with it's
seeming intristic complexity, but have no real purpose
at all.

check it out. read the scripts. Maybe it's different
in debian, who knows, most distros are different. but
i reckon init will start a script to handle the sys-v
stuff.

heres a link

http://www.linuxsa.org.au/meetings/1997-07/init/init.html

oh well. there. 

i hope that isn't tooo wrong. my heads about to
explode as it is. so sorry if i got it a bit wrong.

andrew

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