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From: jfh@killer.UUCP (The Beach Bum)
Newsgroups: comp.bugs.sys5
Subject: Re: CLOCAL, or catch-22
Message-ID: <1382@killer.UUCP>
Date: Sun, 23-Aug-87 01:50:54 EDT
Article-I.D.: killer.1382
Posted: Sun Aug 23 01:50:54 1987
Date-Received: Sun, 23-Aug-87 22:37:15 EDT
References: <325@nsta.UUCP> <25073@sun.uucp> <3607@sdcsvax.UCSD.EDU> <169@edm.UUCP>
Organization: Big "D" Home for Wayward Hackers
Lines: 42
Summary: info on gettydegs (RTFM)

In article <169@edm.UUCP>, steve@edm.UUCP (Stephen Samuel) writes:
> In article <326@nsta.UUCP>, amos@nsta.UUCP (Amos Shapir) writes:
> > The problem  essentially is: How  do you convince  getty to open  a port
> > without  waiting for  carrier, [ ... ]

> The trick is in /etc/{inittab,gettydefs}. find the line that controls your
> tty in inittab and check the last par for getty.  Look for a line in
> gettydefs with the same label in the first field.  Insert a 'CLOCAL' between
> the first and second '#' on that line. (That field defines the STTY state
> BEFORE you login.
>  You might also want to insert a '-CLOCAL' between the second and third '#'
> (this sets the mode AFTER the 'login' message ) so that the machines can tell
> when one of them hangs up.

once again, someone posted first and thought later.

once CLOCAL is cleared and the port closed, there ain't no way i know of
to open a port without using O_NDELAY if DCD isn't asserted.  if you can
keep CLOCAL from getting cleared, then you're fine.  my 5.2 system now
supports DCD on all ports, the old one didn't, so all our terminals are
wired with only RcD, TxD and ground.  so, if CLOCAL gets cleared, there
is no way to login on that port without running a gadget to set CLOCAL.

this is what i learned.  once CLOCAL is set, future open()'s don't block
unless some bozo clears CLOCAL.  usually, loading zeroes into a struct
termio is good enough to hang a port.

there is no way for getty to open the port by munging on gettydefs.  getty
is broke in that respect.  and given the fact that we didn't even wire for
DCD, it can't be fixed easily.  (unfortunately for me and my career, i was
the one who ordered the converters - seems plexus decided that no-one uses
DB-25 connectors for RS-232 anymore :-).

one last thing - omitting a flag from the initial and final fields in
gettydefs doesn't require a `-' in front of the name - you just omit it.

john.
-- 
John F. Haugh II		HECI Exploration Co. Inc.
UUCP:	...!ihnp4!killer!jfh	11910 Greenville Ave, Suite 600
"Don't Have an Oil Well?"	Dallas, TX. 75243
" ... Then Buy One!"		(214) 231-0993