[systemd-devel] "Eye Of Cylon" animation no longer garbles Ctrl-Alt-F9 emergency shell ?

[firefox at firemail.cc]

It is refreshing to see that the Cylon eye is appearantly no longer 
making the Ctrl-Alt-F9 emergency shell unusable.

It being a nice gimmick had the less desirable side-effect of spamming 
the F9 shell, rendering it useless. Cylon was mentioned a few times on 
this mailing-list over the years (was on TO-DO list for a while) and the 
issue popped up in several other places. Relief seems to be here now!

In case, anybody still needs to fix it, say on an old installation, one 
can follow below links, where the Cylon is simply patched out / 
commented out and thus shuts up for good. On stackExchange, they knew no 
better than censoring that post, though.


references:

https://github.com/systemd/systemd/blob/fb4b0465abbd96e6d342e5606c61c919c99a82ff/src/core/manager.c#L229

https://unix.stackexchange.com/questions/481123/make-systemd-debug-shell-usable-again/556410#556410



https://unix.stackexchange.com/questions/556196/fix-dreaded-a-stop-job-is-running-cylon-animation-garbling-systemd-debug-shell?noredirect=1

containing:



The offending line is in systemD where a "cylon" animation garbles the 
F9 console, so the function call needed to be commented out here.

The Source mentions protection against garbling ("screwing" acc. to 
src), but that is sort of feckless here and patching the function-call 
out is quick to do.

Maybe one can manually set manager_is_confirm_spawn_disabled to get rid 
of that obnoxious cylon or simply return immediately until someone fixes 
this. That dreaded linked src line has cost users much wasted time.

The systemd.debug_shell on Alt-F9 is almost useless here, because its 
screen gets garbled with that animated coloured gizmo (named "cylon" in 
above src link) and repeatedly updated message: "A stop job is running 
on ..."

The unit file has

StandardInput=tty
systemctl enable debug-shell.service  # to activate F9-sh

The input is subject to that "spam". How can I get rid of that animated 
nuisance of a notifier? Can hardly imagine I am the only one suffering 
from this kind of obvious problem.

Can I change the "fd" file descriptors of the shell to get rid of the 
spam by systemD?

A kernel commandline like

linux   /boot/vmlinuz-5.4-x86_64 root=UUID=31…… rw 
bootflags=subvol="whatever" udev.log_priority=3 audit=0 
systemd.log_level=debug  systemd.log_target=kmsg  
systemd.StandardError=null

does nothing to remedy the spam either after os-prober

# /etc/systemd/system.conf
# Generated by kcmsystemd control module v1.2.1.
[Manager]
DefaultStandardOutput=journal
DefaultStandardError=journal

is equally futile.

  original post link = 
https://unix.stackexchange.com/questions/556196/dreaded-a-stop-job-is-running-cylon-animation-garbled-systemd-debug-shell-on-a?noredirect=1

So, to defeat the dreaded cylon, I made line 196 near the above link 
read "return ;" compiled, installed… and disposed of the cylon for good. 
Darth Vader wins! Maybe someone finds an alternative way to get the same 
result via kernel commandline ...tty.... or improving the C code to keep 
clean the Alt-F9 shell.