Article View: comp.os.os2
Article #1106Re: Changing the keyboard focus to the COM port
From: //ichael R. //ayne
Date: Thu, 01 Feb 1990 22:02
Date: Thu, 01 Feb 1990 22:02
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2461 bytes
In article <299.25C6D7AD@weyr.FIDONET.ORG> Jim.Gilliland@p3.f209.n141.z1.FIDONET.ORG (Jim Gilliland) writes:
(in response to my request for info on redirecting CMD)
>
>CMD.EXE can be redirected to use a COM port for its STDIN, STDOUT and STDERR,
>but its behavior in this situation may be confusing, especially with respect
>to STDIN. When CMD.EXE discovers that its STDIN has been redirected, it makes
>a couple of changes in its input handling. First of all, it does not echo its
>input. Second, it ignores Carriage Returns (0x0D), and honors only Line Feeds
>(0x0A) as line terminators. So it may well appear that it is not responding
>to input - since you can't see what you type and when you press Enter, nothing
>happens! So perhaps you have been successful without realizing it. It's easy
>to find out - just press Ctrl-J at the end of the line instead of Enter.
Well, there are still a few "problems":
1) <bs> doesn't eliminate the characters.
2) <lf> does indeed terminate lines but does not generate a
corresponding <CR> (This is an annoyance more than totally
devastating).
3) There does not appear to be a way to enter <EOF>. ^Z does
not seem to do anything.
4) There is no way to interrupt a process. ^C does not have any
effect.
5) Shutdown doesn't shutdown the detached process!!!!!
6) We tried some simple commands with devastating results. As an
example, putting a disk into the A: drive and typing
diskcopy A: A:
generated an infinite number of error messages interleaved with
the same number of prompts to insert the disk. I was never
prompted for input though (not even the first time).
So, is it really hopeless to do anything from the COM port or does it just
look that way?
/\/\ \/\/
--
Michael R. Wayne --- TMC & Associates --- wayne@teemc.uucp
INTERNET: wayne%teemc.uucp@sharkey.cc.umich.edu uunet!edsews!teemc!wayne
Operator of the only 240 Horsepower UNIX machine in Michigan
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!sharkey!cfctech!teemc!wayne From: wayne@teemc.UUCP (//ichael R. //ayne) Newsgroups: comp.os.os2 Subject: Re: Changing the keyboard focus to the COM port Message-ID: <91381@teemc.UUCP> Date: 1 Feb 90 22:02:17 GMT References: <299.25C6D7AD@weyr.FIDONET.ORG> Reply-To: wayne@teemc.UUCP (/\/\ichael R. \/\/ayne) Organization: TMC & Associates, Troy, MI Lines: 39