[systemd-devel] [PATCH 2/3] ask-password: mention magic key to start over

[Lennart Poettering]

On Wed, 16.03.11 04:19, Jan Engelhardt (jengelh at medozas.de) wrote:

> 
> On Wednesday 2011-03-16 03:58, Lennart Poettering wrote:
> 
> >On Wed, 16.03.11 03:50, Jan Engelhardt (jengelh at medozas.de) wrote:
> >
> >Does this patch really make sense? C-u is in no way magic here, it works
> >on every terminal. I am not sure why we should mention this here
> >explicitly.
> 
> There have been sufficiently enough console programs throughout my Linux 
> life that I have come to regard only certain control sequence as 
> reliable, and ^U is not amongst these.
> 
> Midnight Commander rebinds ^U to swap panels,
> gpg2/pinentry-ncurses takes ^U verbatim,
> nano and editors of that family make ^U a paste rather than a kill,
> (re)(al)pine and MUAs of that family inherit nano behavior.
> 
> The reliable sequences I mentioned... just ^C, and surprisingly ^D.
> And maybe ^S, because that always interferes when you least expect it :-)

Well, all these keycodes are actually handled by the kernel and in the
terminal layer as part of ICANON (^U is VKILL to be precise). See
tcsetattr(3) for more information.

I'd argue that tools which redefine ^U and ^H and ^C to unrelated
operations have made very poor choices, and they should probably be
fixed. But that doesn't change the fact that the kernel default is to
map ^U like we do, and I don't think we need to explicitly advertise
that we follow the default behaviour of the kernel...

Lennart

-- 
Lennart Poettering - Red Hat, Inc.