linux-kernel - Re: [PATCH v3 2/2] tty/sysrq: Add configurable handler to execute a compound action

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Date:   Fri, 2 Oct 2020 14:54:29 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Andrzej Pietrasiewicz <andrzej.p@...labora.com>
Cc:     linux-kernel@...r.kernel.org,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Jiri Slaby <jslaby@...e.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        kernel@...labora.com
Subject: Re: [PATCH v3 2/2] tty/sysrq: Add configurable handler to execute a
 compound action

On Tue, Aug 18, 2020 at 01:28:25PM +0200, Andrzej Pietrasiewicz wrote:
> Userland might want to execute e.g. 'w' (show blocked tasks), followed
> by 's' (sync), followed by 1000 ms delay and then followed by 'c' (crash)
> upon a single magic SysRq. Or one might want to execute the famous "Raising
> Elephants Is So Utterly Boring" action. This patch adds a configurable
> handler, triggered with 'C', for this exact purpose. The user specifies the
> composition of the compound action using syntax similar to getopt, where
> each letter corresponds to an individual action and a colon followed by a
> number corresponds to a delay of that many milliseconds, e.g.:
> 
> ws:1000c
> 
> or
> 
> r:100eis:1000ub

A macro language for sysrq commands, who would have thought...

Anyway, _why_ would userland want to do something so crazy as this?
What is the use-case here?

thanks,

greg k-h