Re: Should the readline *-meta flags reset when $LANG changes?

[Chet Ramey]

On 8/11/22 5:56 PM, Koichi Murase wrote:

> Can we also change the behavior of TERM in a similar way with option
> 4?  Currently, a temporal change of TERM clears keybindings of some
> keys (home, end, right, left, etc.) even when the temporal change does
> not survive across multiple calls of readline:

I finally got back to look at this, and I couldn't reproduce it. That was
expected, since the arrow key binding functions are pretty careful not to
overwrite an existing binding. Then I figured out what was going on.

> $ bash-dev --norc
> $ echo "$TERM"
> screen.xterm-256color
> $ bind '"\e[1~": bell'

This unbinds the key sequence, since `bell' is not a valid bindable command
name. I happened to be using `previous-history' and testing with "\eOH",
which rebinds it instead.

> $ bind -q beginning-of-line
> beginning-of-line can be invoked via "\C-a", "\eOH", "\e[H".
> $ TERM=dumb infocmp >dumb.ti

Bash does call rl_reset_terminal here when restoring the original value of
TERM, and it attempts to bind the arrow keys and the other specials (Home,
etc.). It finds that "\e[1~" is not bound, and binds it.

> $ bind -q beginning-of-line
> beginning-of-line can be invoked via "\C-a", "\eOH", "\e[1~", "\e[H".

I think the "TERM=$TERM" idiom to reset the readline terminal settings
without overwriting existing key bindings is useful enough to retain the
current behavior.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/