Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!bu-cs!bloom-beacon!athena.mit.edu!jik
From: jik@athena.mit.edu (Jonathan I. Kamens)
Newsgroups: comp.unix.questions
Subject: Where Goeth the Line-editing? (was Re: Strangeness in shell)
Message-ID: <13303@bloom-beacon.MIT.EDU>
Date: 6 Aug 89 18:50:37 GMT
References: <432@mccc.UUCP> <9700009@osiris.cso.uiuc.edu> <2277@auspex.auspex.com> <10639@smoke.BRL.MIL> <5404@ficc.uu.net> <10650@smoke.BRL.MIL> <673@skye.ed.ac.uk>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: jik@athena.mit.edu (Jonathan I. Kamens)
Organization: Massachusetts Institute of Technology
Lines: 28


  A good place to look for an example of one way to have a uniform
line-editing interface is in Multics (Multics people correct me if I'm
wrong, because I'm writing this second-hand -- I never even got to
login to MIT Multics before it went away :-().

  In multics, it was possible to install a driver that lived at the
gateway between the actual terminal and user processes.  This driver
would intercept and process *all* input before sending it to the
process.  Therefore, if you wrote a line-editing driver and installed
it, it would work for *every* program on the system, without fail.
There were, of course, ways to turn off the line-editing features for
programs that needed character-by-character input.

  So Multics did what several people have been suggesting -- make the
terminal editing capabilities separate both from the program and the
actual terminal by putting it in a driver that can be modified or
replaced by the user.

  Wouldn't it be great if you could use line-editing in ed?  History
substitution?  Wouldn't it be great if all of the shells used the same
characters and commands for history substitution and command-line
editing?  You get the idea....

Jonathan Kamens			              USnail:
MIT Project Athena				432 S. Rose Blvd.
jik@Athena.MIT.EDU				Akron, OH  44320
Office: 617-253-4261			      Home: 216-869-6432