Re: [PATCH 0/7] TTY Keyboard Status Request

From: Pavel Machek
Date: Sun Jun 09 2019 - 13:46:51 EST


> This patch series introduces TTY keyboard status request, a feature of
> the n_tty line discipline that reserves a character in struct termios
> (^T by default) and reacts to it by printing a short informational line
> to the terminal and sending a Unix signal to the tty's foreground
> process group. The processes may, in response to the signal, output a
> textual description of what they're doing.
> The feature has been present in a similar form at least in
> Free/Open/NetBSD; it would be nice to have something like this in Linux
> as well. There is an LKML thread[1] where users have previously
> expressed the rationale for this.
> The current implementation does not break existing kernel API in any
> way, since, fortunately, all the architectures supported by the kernel
> happen to have at least 1 free byte in the termios control character
> array.

I like the idea... I was often wondering "how long will this dd take". (And in
case of dd, SIGUSR1 does the job).

I assume this will off by default, so that applications using ^T today will not
get surprise signals?