Selectively disable login at specified line?

[Brandon S. Allbery]

As quoted from <105 at minya.UUCP> by jc at minya.UUCP (John Chambers):
+---------------
| with a new one when I'm convinced it is working there.  Why doesn't the
| whole world just adopt the /etc/inittab version of init?  Oh, yes, there
| is the question of the source license...perhaps I'll try my hand at writing
| that and putting it in the public domain next.  On the other hand, maybe
| I won't find the time.  Any takers?
+---------------

I have no doubt that I could clone System V's /etc/init.  The problem is
that in various versions of Unix, functionality has drifted around between
init and getty; and both impact the structure and/or ordering of /etc/utmp,
which can break login and any program which uses getlogin().  (I know, I tried
to install a System V getty with the utmp routines changed to write System
III-compatible utmp records; and login immediately broke with "No utmp
entry".)

Thus, to replace /etc/init you must at minimum replace /etc/getty, and you
must either know the format *and* *ordering* of /etc/utmp -or- be able to
recompile most of the user-level programs on the system.  (And if you can
do the latter you'd have no trouble doing the former.)

BTW, does anyone know how System III decides which records in /etc/utmp are
for which /dev/tty* devices?  I still want to replace the getty on here,
since we are going to need a uugetty-clone here pretty soon...  (Suggestions
to upgrade our O/S may be sent to /dev/null.  It's not an option.)

++Brandon
-- 
Brandon S. Allbery, comp.sources.misc moderator and one admin of ncoast PA UN*X
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