Path: utzoo!attcan!lsuc!eci386!woods
From: woods@eci386.uucp (Greg Woods)
Newsgroups: comp.unix.questions
Subject: Re: Unix deficiencies/problems
Summary: Typeahead, and why Unix does it the way it does.
Keywords: line discipline, typeahead, tty, shell
Message-ID: <1989May12.221209.27896@eci386.uucp>
Date: 12 May 89 22:12:09 GMT
References: <810038@hpsemc.HP.COM> <810046@hpsemc.HP.COM> <159@dg.dg.com> <424@algor2.UUCP> <676@dtscp1.UUCP> <1528@cmx.npac.syr.edu> <8892@csli.Stanford.EDU> <2914@cps3xx.UUCP>
Reply-To: woods@eci386.UUCP (Greg Woods)
Organization: R. H. Lathwell Associates: Elegant Communications, Inc.
Lines: 24

In article <2914@cps3xx.UUCP> rang@cpsin3.cps.msu.edu (Anton Rang) writes:
> ....  But it's much faster to use typeahead.  Having it
> echo in the middle of my output is quite annoying, though.  (Then
> again, I worked with Apple ][, IBM-PC, and VMS systems--which have
> typeahead working "right"--before I worked with UNIX; maybe one gets
> used to this weirdness eventually.)
>   Does anyone know the original reason for the immediate echoing?

So that you can see what you've typed, and there by correct any
mistakes you might have made.  Of course any good shell will be
re-echoing what you've typed on the prompt line (ala ksh, tcsh,
and some csh's) at time of execution.  Primarily you'll only be
using typeahead if you have entered a command which takes a
considerable amount of time, and you do not want to, or cannot
interrupt it and re-start it in the background.  And when spurious
output from this command interrupts your typing, perhaps causing
you to make a mistake, you become acutely aware of the reasoning
behind the invention of the BSD newtty line discipline, and its
re-type feature.
-- 
						Greg A. Woods

woods@{{utgpu,eci386,ontmoh,tmsoft}.UUCP,gpu.utcs.UToronto.CA,utorgpu.BITNET}
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