bug#20922: blinking in linux console

bug#20922: blinking in linux console

[Samuel Wales]

summary: can emacs do ANYTHING to not blink in the linux console?

linux is at its worst when you have to debug things in the console.  you
usually do not have your shell tools or emacs config or filesystem
hierarchy.  dead and broken keys impair the emacs experience.  and yet
you have to (1) solve the original problem and (2) get your system running.

this is exactly the time when some of us do NOT need the cursor to
blink.  in my own case, for health reasons, i cannot tolerate a
blinking cursor.  this impedes fixing the computer significantly and
is a problem in its own right.  but i know that others find it highly
annoying even though they do not have health reasons.  so i won't call
it an accessibility problem even though it is.  (aside: for some
reason, sometimes the free software community tends to dismiss
accessbility needs, while taking annoyance preferences seriously.
thus i sometimes try to cover both bases when it is an accessbility
issue.)

now, inb4, there are a few websites that cover the linux console.  even
on emacs sites.  for example:

  1) you can emit ansi sequences to turn the cursor into a red block.
  this fails, because emacs resets everything and blinks the cursor
  again.  also, if you are in the console in the first place, you
  possibly don't have access to this.

  2) you can do some kind of nonsense with terminal definitions, which
  fails because i don't remember why.  also, if you are in the console
  in the first place, you possibly don't have access to this.

  3) you can echo 0 > /sys/class/graphics/fbcon/cursor_blink.  this
  fails, because i don't know, it just fails.  also, ....

obviously, linux needs to grow up and stop assuming nobody needs to not have
kewl blinky flashy things.  so this should be fixed in linux.

but can emacs fix this so that it is not a problem in emacs any more?
regardless of whether linux has decided to fix the problem?

for example, can it fix whatever resetting the terminal broke?  can it
set its own terminal definition?

i do not know whether this is possible in principle or not.

(inb4 nothing at the lisp level in emacs fixes this, of course.)


thanks.


In GNU Emacs 24.4.1 (x86_64-pc-linux-gnu, GTK+ Version 3.4.2)
 of 2015-01-11 on maritornes, modified by Debian

bug#20922: blinking in linux console

[Alexis]

Samuel Wales <samologist@gmail.com> writes:

>   3) you can echo 0 > /sys/class/graphics/fbcon/cursor_blink. 
>   this fails, because i don't know, it just fails.

This method works for me. i'm running Emacs 24.5.2 with Linux 
kernel 3.16.0-4 on Debian Jessie x86_64.

Do you get no error messages when you issue the above command (as 
root, of course)? Does subsequently doing:

$ cat /sys/class/graphics/fbcon/cursor_blink

produce "0" as the output?


Alexis.

bug#20922: blinking in linux console

[Stefan Kangas]

Alexis <flexibeast@gmail.com> writes:

> Samuel Wales <samologist@gmail.com> writes:
>
>>   3) you can echo 0 > /sys/class/graphics/fbcon/cursor_blink.   this fails,
>> because i don't know, it just fails.
>
> This method works for me. i'm running Emacs 24.5.2 with Linux kernel 3.16.0-4 on
> Debian Jessie x86_64.
>
> Do you get no error messages when you issue the above command (as root, of
> course)? Does subsequently doing:
>
> $ cat /sys/class/graphics/fbcon/cursor_blink
>
> produce "0" as the output?

I don't think Emacs controls the appearance of the Linux console, so
this is not a bug in Emacs.  I'm therefore closing this bug.  If
that's incorrect, please reopen.

Best regards,
Stefan Kangas

bug#20922: acknowledged by developer ()

[Samuel Wales]

i didn't mean to imply it is an emacs bug.

but even when i fix the cursor in the console, running emacs makes it
blink again.  probably not due to a bug, but because it does something
that has a bug?

in any case, it is a request for emacs to work around the bug, if possible.

thanks.

bug#20922: acknowledged by developer ()

[Eli Zaretskii]

> From: Samuel Wales <samologist@gmail.com>
> Date: Sun, 29 Sep 2019 16:35:56 -0700
> 
> i didn't mean to imply it is an emacs bug.
> 
> but even when i fix the cursor in the console, running emacs makes it
> blink again.  probably not due to a bug, but because it does something
> that has a bug?
> 
> in any case, it is a request for emacs to work around the bug, if possible.

Does it help to set visible-cursor to nil?

bug#20922: acknowledged by developer ()

[Samuel Wales]

On 9/29/19, Eli Zaretskii <eliz@gnu.org> wrote:
> Does it help to set visible-cursor to nil?

;; this is a last resort
;;   does not work in linux console [2016-05-13 Fri 12:52]; that
;;   blinks an underscore now
;; (setq visible-cursor nil)

i have not tried it just now, but i never got that to improve the experience.

-- 
The Kafka Pandemic

What is misopathy?
https://thekafkapandemic.blogspot.com/2013/10/why-some-diseases-are-wronged.html

The disease DOES progress. MANY people have died from it. And ANYBODY
can get it at any time.

bug#20922: acknowledged by developer ()

[Samuel Wales]

just realized i don't need to reboot to try it.

in linux console in 4.9.0-11-amd64

1) i issue the inscrutable ansi sequence to make a nice red block cursor
2) i run emacs which produces a blinking white block
4) i setq visible-cursor to nil which produces a blinking underscore

bug#20922: acknowledged by developer ()

[Eli Zaretskii]

> From: Samuel Wales <samologist@gmail.com>
> Date: Mon, 30 Sep 2019 13:25:06 -0700
> Cc: 20922@debbugs.gnu.org
> 
> just realized i don't need to reboot to try it.
> 
> in linux console in 4.9.0-11-amd64
> 
> 1) i issue the inscrutable ansi sequence to make a nice red block cursor
> 2) i run emacs which produces a blinking white block
> 4) i setq visible-cursor to nil which produces a blinking underscore

Then I guess the problem is that Emacs sends the "ve" command (normal
cursor) to the terminal?  I'm not an expert on terminfo, but if
there's a way for a program to read the cursor properties, then Emacs
could do that at startup, and keep it, or restore it on exit.

Alternatively we might have a feature whereby users could set
attributes of the text-mode cursor for Emacs to use in its text
frames.  Patches welcome.