Input Line Editing

[Theodore Y. Ts'o]

In article <919 at esunix.UUCP> bpendlet at esunix.UUCP (Bob Pendleton) writes:
>From article <6192 at bloom-beacon.MIT.EDU>, by tytso at athena.mit.edu (Theodore Y. Ts'o):
>> were typed to that tty.  For example, if you started editing a file
>> using /bin/ed (or some other interactive program), and typed hundreds
>> of "n", "p", "i", "a", and "s/foo/bar/" commands, when you exited to 
>> the shell, do you really want to step through those hundreds of /bin/ed
>> commands?  The shell isn't going to do anything useful with them.  What
>
>If ed sets cbreak or raw mode then ile won't record any of the
>characters going either direction.

That wasn't the point.  You know as well as I do that /bin/ed doesn't
turn on cbreak or raw mode.  The point was that I didn't want /bin/ed's
(or any other interactive program) mixing with the history of the
shell.  The fact that ile does the right thing with emacs is
wonderful, but it doesn't obscure the above problem.

>On the other hand in some programs you might like to have a history
>and line editing capability but not have that history in your "global"
>history. So, just invoke "ed" as "ile ed" or even alias "ed" to "ile
>ed". Then while you are running ed you have a local history that goes
>away as soon as you exit ed. But, the input line editing stays
>consistent. 

That's certainly a solution.  One thing I've discovered since my last
posting is that ile co-exists quite peacefully with a shell with
built-in line editing.  This way, you can have the best of both worlds.

A hack which I'm thinking about designing for our shell is a builtin
which would fork a copy of shell and have it work in the same manner
as ile does for a certain command.  This way, while you're in the
shell, you don't get the efficiency hit of a pty pair, and the user
can set up his keybindings and his keymaps at will.  Then, when he
wants line editing for an interactive program, the line editing
environment will be duplicated.  This allows a user to modify his line
editor on the fly, and have the changes be reflect the next time he
wants line editing.

>I can't force my users to use one shell. I don't have time to hack several
>shells. Especially since I don't think I have source for all of them.
>And I can't count on having shell source in the future. I can count on
>having the source to ile. We aren't all still in academia. 

Well, we could induce Berkeley (and other vendors) to put some sort of
user-customizable line editior in the next csh.  Or, you could just
run GNUemacs in shell mode.... you should always have source code for
that :-)

						- Ted
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Theodore Ts'o				mit-eddie!mit-athena!tytso
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