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From: avg@hq.demos.su (Vadim G. Antonov)
Newsgroups: comp.unix.shell,comp.unix.misc,comp.unix.internals
Subject: Re: Questions about rewriting the History function.
Message-ID: <1990Oct20.143032.25212@hq.demos.su>
Date: 20 Oct 90 14:30:32 GMT
References: <1990Oct19.170143.7674@polyof.poly.edu>
Reply-To: avg@hq.demos.su (Vadim G. Antonov)
Organization: DEMOS, Moscow, USSR
Lines: 37

In article <1990Oct19.170143.7674@polyof.poly.edu> mhoffman@george.poly.edu writes:
>
>	I am working on a senior project to rewrite the history function for    UNIX.  My goal is to have the new history functon work like it does in MS_DOS.
>i.e. I want to be able to call up past commands and edit them by using the 
>control <hjkl> characters.  Additionally, I would like to write this as a stand alone program so that I do not have to rewrite the shell.

	I've written the such program (it's about 50 lines :-) sorry
	but I haven't it handy. To use it one should add the following
	alias to .cshrc:

		alias r 'eval `history | redo`'

	so if you want to edit previous lines you should enter the
	command r.

	This program was died because we (Sergey Ryzhkov & I) have made
	our own revision of csh with builtin line-editing facility.
	(So there is no need to enter commands to go to editing mode).

	It was not so simple because Unix tty drivers handle modes switching
	in the very *ugly* way - I've spent a week trying to make a
	sequence allowing do it without flushing characters. (Oh I use
	to type commands *before* a prompt appears :-).  Another
	problem was the proper processing of ^Z and ^Y - some our
	ttys used this chars (as well as ^Q and ^S) in escape sequences.
	We decided to read all characters as ordinary ones and
	process it in program - and I had to hack tty driver to allow
	TIOCSTART and TIOCSTOP to work with ordinary ttys as well as with
	ptys. Problem with ^Z/^Y was solved by non-trivial hack in csh's
	internals. Anyway it was done and works under DEMOS 2.2.

	Thus I suggest you to do the thing in the first way, it's
	much simplier and practically as suitable as the second for
	an endluser.

	Vadim Antonov
	DEMOS, Moscow, USSR