NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/comp/sys/sun/admin/5019

Internet Message Format | 1992-07-27 | 1.8 KB

Path: sparky!uunet!munnari.oz.au!metro!usage!sphinx!pta!yarra!melba.bby.oz.au!gnb
From: [e-mail] (Gregory N. Bond)
Newsgroups: comp.sys.sun.admin
Subject: /etc/printcap, terminfo and VMIN.  AAAARRGGGGHHHH!!!
Message-ID: <[e-mail]>
Date: 27 Jul 92 06:11:29 GMT
Sender: [e-mail] (news READER id)
Organization: Burdett, Buckeridge & Young, Melbourne, Australia
Lines: 27
Nntp-Posting-Host: duke

I'm attempting to connect a PostScript printer to a serial port on a
3/80 running 4.1.1.  Being PostScript, I need to be able to get the ^D
back from it once the print job is done.  This means the serial port
must be in -icanon mode, otherwise the ^D gets turned into EOF.

However, when I set -icanon in the printcap "ms=..." entry, I get the
port set up with VMIN=4 and VTIME=0.  This means the read will never
return until 4 characters are available, and the spooler program hangs
indefinitely as there is only 1 ^D available.  Manually setting VMIN
to 1 with stty unhangs the daemon and jobs start printing normally
(until the daemon runs out of work, closes the port and resets VMIN.)

And there appears to be no way to have lpd reset VMIN itself because
the ms= printcap entry doesn't accept the "min n" arguments that stty
does.  According to the termio(4), the initial value of MIN is 1, so
who is setting it to 4 (which is ^D; no surprise as VMIN = VEOF)?

Surely I'm not the first person to discover this one?  Anything I can
do other than make the input filter change VMIN itself?

[All our other printers are connected via terminal servers.  No such
problems there.  Terminal control used to be so easy in V7!]

Greg.
--
Gregory Bond <[e-mail]> Burdett Buckeridge & Young Ltd Melbourne Australia
"Take my archetypes - please!" - Henny Jungman ([e-mail])