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Message-Id: <5.2.0.9.2.20030314161234.02da66d8@pop3.cris.com>
X-Sender: rrschulz AT pop3 DOT cris DOT com
Date: Fri, 14 Mar 2003 16:26:07 -0800
To: cygwin AT cygwin DOT com
From: Randall R Schulz <rrschulz AT cris DOT com>
Subject: Re: agetty problem - inconsistent echo
In-Reply-To: <b4tqt0$cmn$1@main.gmane.org>
References: <b4tml1$t6q$1 AT main DOT gmane DOT org>
 <5 DOT 2 DOT 0 DOT 9 DOT 2 DOT 20030314150750 DOT 02e033b0 AT pop3 DOT cris DOT com>
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BB,

The TERM variable is used to indicate to programs that do things like 
cursor addressing or color how to effect the display features they 
require. It is irrelevant otherwise.

The "min" tty setting, though it appears correct as you point out, 
would produce the symptoms you describe if set to 2.

However, just for kicks, I decided to try setting "min" to 2 on my 
system. It seems to have no effect! It does not matter whether I'm 
running with CYGWIN=tty or not.

By the way, the command line syntax and output from the "stty" command 
is somewhat idiosyncratic. When a keyword is prefixed with a minus 
sign, that mode or option is (turned) off. When the minus sign is 
missing, the mode or option is (turned) on. The same keywords and on / 
off syntax is used on the command line to turn modes and options on and 
off and in the output to display the current tty settings.

Unfortunately, I cannot suggest what might really be happening on your system.

What sort of terminal are you connecting to the serial port? What is 
Hyperterminal? A terminal emulator? Are you connecting from another 
computer? From a different serial port on the same computer?

Which shell are you using when you connect via the serial port?

Randall Schulz


At 16:08 2003-03-14, BB wrote:
>Running stty -a dialed in from Hyperterminal I get the results below.  min
>is set to 1. The only differences from what you sent in your reply are
>echoe, echoctl, and echoke without '-'.
>
>Does it matter what the TERM environment variable is set to?  I have
>configured agetty to set it to vt100 and to nothing (defualt to cygwin).  I
>get the same results.
>
>The problem is not just with the end of line \r.  As I type characters,
>every second character causes the echo of the two characters.  If the end of
>line happens to be the second of a pair, the command works.
>
>$ stty -a
>speed 38400 baud; rows 24; columns 80; line = 0;
>intr = ^C; quit = ^\; erase = ^H; kill = ^U; eof = ^D; eol = <undef>;
>eol2 = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W;
>lnext = ^V; flush = ^O; min = 1; time = 0;
>-parenb -parodd cs8 -hupcl -cstopb cread -clocal -crtscts
>-ignbrk brkint -ignpar -parmrk -inpck istrip -inlcr -igncr icrnl ixon -ixoff
>-iuclc ixany imaxbel
>opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0
>ff0
>isig icanon iexten echo echoe -echok -echonl -noflsh -tostop echoctl echoke
>
>"Randall R Schulz" <rrschulz AT cris DOT com> wrote in message
>news:5 DOT 2 DOT 0 DOT 9 DOT 2 DOT 20030314150750 DOT 02e033b0 AT pop3 DOT cris DOT com...
> > BB,
> >
> > Well, it's a long shot, but System V Unix-style tty drivers, including
> > the Cygwin emulation on Windows, have a parameter, "min," that tells
> > the minimum number of characters that must be present in the input
> > buffer before it will be activated. Programs that use the readline
> > library (BASH, e.g.) or that operate in a character-by-character mode
> > (Vim or Emacs, e.g.) will typically have this set to 1:
> >
> > (running BASH)
> > % stty -a
> > ...
> > ... min = 1; time = 0;
> > -parenb -parodd cs8 -hupcl -cstopb cread -clocal -crtscts
> > ...
> > isig icanon iexten
>echo -echoe -echok -echonl -noflsh -tostop -echoctl -echoke
> >
> >
> > Your symptoms are consistent with "stty min 2", though I can think of
> > no reason this would occur (a bug in agetty?), but you can confirm it
> > by running "stty -a" and looking at what min setting it reports.
> >
> > Randall Schulz
> >
> >
> >
> > At 14:56 2003-03-14, BB wrote:
> > >I am using agetty with both Win95 and WinXP.  On WinXP everything works
> > >fine. On Win95, I have a problem.
> > >
> > >When the Win95 machines modem answers the call, agetty correctly 
> prompts for
> > >the login: id.  I type it in and notice that every character I type is
> > >immediately echoed back to me (I'm using hyperterminal).  This is 
> as I would
> > >expect based on the agetty code.  Each character is read and 
> written back to
> > >the tty.
> > >
> > >Once I enter the login id, agetty spawns login.exe.  From this 
> point on, the
> > >characters I type are echoed back to me on every second character.  The
> > >problem is that if I type a command with an odd number of 
> characters such as
> > >"ls\r", nothing happens.  Once I type one more '\r' or even a space, the
> > >command is executed.  The extra character I typed is also echoed back,
> > >usually after the next shell prompt.
> > >
> > >What could be causing my input to be processed two characters at a time.
> > >This does not occur on an XP machine running agetty.
> > >
> > >Thanks


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