On Sun, Apr 10, 2011 at 1:34 AM, Todd And Margo Chester
<[log in to unmask]> wrote:
> Interesting. Why would you want to stop or restart "Brctl addif br1 eth1"?
For this very specific instance, you might not. The difficulty enters
when you teach or encourage other people to pull this stunt with other
settings, and they adopt it as standard practice. Having to edit or
verify settings in a non-modular, unified /etc/rc.local has
traditionally been awkward, error-prone, and liable to make systems
hang or crash at boot time. I've had far too many systems in the
last..... oh dear lord, I've been at this too long, over 20 yers....
get edited by a local "admin" who turned /etc/rc.local into a swamp of
unparseable, mis-ordered, and impossible to manage personalized
scripting. The whole SysV init script layout as implemented in our
upstream vendor's tools was designed to provide individual
configuration or service control, and includes reporting on the state.
The big advantage is that you can turn it *off*, and disable it,
without having to edit the potentially fragile /etc/rc.local file.
Another advantage is when you tell people to edit /etc/rc.local, if
they use the wrong editor, they'll break the symlink to
/etc/rc.d/rc.local. Edit it with Emacs and neglect to follow the
symlink, and you'll fail to record your edits in the symlinked target.
And if you mishandle backing up and restoring your copy, you'll also
break the symlink.
It's subtle fragility that is undesirable in any production environment.
> And, at least on my system, rc.local is started by S99local
>
> init.d]$ ls -al ../rc5.d/S99local
> lrwxrwxrwx 1 root root 11 Nov 17 09:10 ../rc5.d/S99local -> ../rc.local
>
> I can see your point if you wanted to stop or restart things, or reverse
> them
> at shutdown, but if you only want to run them once, S99local (rc.local) is
> a good place to put them. I have done this for many years. Never once
> had a problem. What am I missing?
You're missing over 20 years of pain and paranoia (which describes my
IT career). It's not wildly unreasonable for a one-off. I've had to
deal with lots of cluttered rc.local's, and unweave them, to stabilize
systems. Deploying this kind of tweak to, say, 20 systems running kvm
is a lot easier if you can put it in a separate cron script.
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