[comp.unix.misc] Questions about rewriting the History function.

roseann@polyof.poly.edu (RoseAnn Ammendolea) (10/20/90)

	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.
	The main approach I will use will be to store the previous commands in alinked list.  My only problem is that I do not know how to intercept the commandonce it has been entered, before it gets executed.  Likewise, I do ont know how to execute the command once I have retreived it form the list. i.e. I want to   display the command for possible editting and execute it when the carriage
return is pressed.
	If there is anyone out there that has some ideas or suggestions, they   would be greatly appreciated. Also if anyone knows where I might be able to find the source code for the present HISTORY function or the R function I would like to know so I can look at it and gain some insight to my project.

P.S. Please do not send replys to posters address use the address in the 
     reply-to header.


Thank You.			Mark

avg@hq.demos.su (Vadim G. Antonov) (10/20/90)

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

ping@cubmol.bio.columbia.edu (Shiping Zhang) (10/22/90)

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.


We have a shell script which lets you edit history commands
before they are reexecuted.
-ping