[Linux-disciples] Where to put startup instructions

[Adam Rosi-Kessel]

On Sun, May 08, 2005 at 11:33:41AM -0400, Stephen R Laniel wrote:
> On Sun, May 08, 2005 at 11:25:59AM -0400, Adam Rosi-Kessel wrote:
> > So my guess would be put it in /etc/rcS.d, but I don't know if that is
> > "canonical."
> Just to reclaim a small bit of my Debian Manhood, I was
> aware of the /etc/init.d/-and-symlinks bit. But I think it's
> a little tricky, because I need to know when /proc is going
> to come up; only after it's up can I run the command I'm
> looking to run.

Note that rcS.d is a little different from rc#.d.  I think it's that
rcS.d goes before any of the runlevels, but I may be missing some
subtlety.

> So I guess my question was: is there any good general method
> for figuring out which of the /etc/rcN.d directories a given
> command should go in, or do we have to figure it out in an
> ad-hoc way?

Well, in Debian we really don't have that many runlevels. There is 0
(halt) and 6 (reboot), which aren't relevant here. Then 1 is single user
mode, and 2-5 are all the same.

Commands are executed in alphabetical order for each runlevel.  A command
(symlink) starting with 'S' will be called with 'start', with 'K' will be
called with 'stop' (as argument).  Hence all the 'K's in /etc/rc1.d,
because in single user mode you shut most things down.

As far as echo-ing something into /proc, you just need to do it after
proc is mounted, which I believe will happen in
/etc/rcS.d/S35mountall.sh.  So anything in any other runlevel, or after
S35, should work fine.

> I should be able to say, for instance, that your (Adam's)
> ssh-login-blocker script can only go in after sshd has
> started. I specify enough of these constraints ("only go
> in after daemon D_1," "only go in before daemon D_2," etc.),
> and Unix places the daemon in a position that's consistent
> with the constraints I've given (or tells me that my
> constraints are impossible to satisfy).

Actually, it doesn't matter when ssh_login_blocker starts--it doesn't
depend or expect the ssh daemon to be running first.  So in this case you
could start it anytime after the filesystems are mounted.

> Anyway, that's the dream. I'll look around for a specific
> place to put this /proc instruction.

I would suggest /etc/rcS.d/S40proc or something like that.
-- 
Adam Rosi-Kessel
http://adam.rosi-kessel.org
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