[NTLUG:Discuss] Hosed up my system

[bryn konti]

Thanks Chris and everyone else for your replies.  I
have to say I don't like to depend on admin tools like
linuxconf, although I confess I do use  them on
occasion, I believe it's better to understand how to
perform most configurations from the command line. I
think I have a general idea of how System V init works
but I am still unclear on the theory of exactly how it
was designed to be used..I mean other than that the
scripts you start in whatever runlevel you normally
boot to should be properly brought down in runlevel 6.
  I am also curious why most distributions use the ATT
System V initialization scheme rather than BSD style
init....and  I don't know  what  advantage if any that
System V init has over the BSD method. 


--- Chris Cox <cjcox at acm.org> wrote:
> bryn konti wrote:
> > 
> > Thanks for replying Chris.....the more people
> explain
> > how linux and unix work, the more I understand.  I
> > have just two more questions on the subject of
> > runlevels:  What are the differences between unix
> and
> > linux runlevels and is there a standard
> configuration
> > method to add/remove  and start/stop the rc
> scripts in
> > various runlevels?
> 
> The standard for System V init is to have scripts
> labeled
> SXXname placed into directories typically at
> /etc/rc#.d.
> Where XX is a two digit number and # is a runlevel.
> The file /etc/inittab will show you how all of this
> gets kicked off.
> 
> The scripts in /etc/rc#.d are often times symbolic
> links
> to the real script residing in /etc/init.d.  But the
> scripts don't have to be symbolic links, nor do they
> have to have representation in /etc/init.d.  I will
> warn
> you that a particular distribution's administration
> tools may make some assumptions with regards to
> this.
> Of course, "real penguins" don't use the admin tools
> :-).
> 
> The other style is often referred to as BSD init
> script
> style.  In fact, there are some Linux distributions
> that
> prefere this style over the System V one.  However,
> I've
> always found maintaining the BSD style to be more
> difficult and usually very error prone.  You can do
> a
> google search and find some examples (for either
> style
> really).
> 
> SuSE takes a fairly unique approach by enabling
> services
> via variable tags that are sourced in from rc.config
> into every runlevel script.  Their reasoning is that
> the order in which services have to be brought up
> and
> down is not clear, so they link in every script at
> the "proper" SXXname or KXXname in the "proper"
> runlevel
> directory... and then the variable tags tell the
> system
> whether the script needs to do anything or not.
> This is SuSE's way of solving the daemon order of
> execution problem.
> 
> Others have already talked about the runlevel
> numbers, the
> ones in common:
> 0 - halt
> 1 - single user
> 2 - networked
> 6 - reboot
> 
> 3 is usually broader network services (typically
> NFS)
> 5 is often X Window System, but in Solaris, as
> mentioned,
>   it has X even at runlevel 2.
> 
> On a well configured system you should be able to
> move
> between the runlevels using 'init #' or 'telinit #'
> without the system getting confused (dare you to try
> this with Solaris btw especially if you have a lot
> of
> network services configured..NIS, NFS, etc).
> 
> Regards,
> Chris
> 
> _______________________________________________
> http://www.ntlug.org/mailman/listinfo/discuss


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