grub bootloader trick doesn't work

This is really weird, why can't I edit my post to finish about what happened after the last boot???

Anyway, after Attempt 05, again, just like the previous attempts, no positive results. I can't see the screen at all in the day and it's WAY too bright in the night.

You can not edit the post, only the comments to the post (until someone comments on the comment).

I have screen brightness issues on my older lappy. Basically this old, very old lappy would reset the brightness to the lowest setting each time it rebooted. What I did to fix it is this ->

sudo mousepad /etc/rc.local

(I'm on Xfce, hence mousepad. You will have 'gedit')

Add the liner:

echo 15 > /sys/class/backlight/intel_backlight/brightness

which in my specific case is actually:

echo 15 > /sys/class/backlight/acer-wmi/brightness

Notice that 15 is the max value of this particular monitor.
Hope this gives you some hint..

I use "xbacklight" to change the amplification of my screen.

I have the following code in my ".bashrc" file:

function light () {
    if [ $# == 1 ]; then
        xbacklight -steps 1 -set $1
    elif [ $# == 0 ]; then
        xbacklight
    fi
}

I can then enter "light" to see the current level or "light 50" (for example) to set it.

I would like to use the above in a root daemon, but I noticed that my old root daemon that worked in Lubuntu 14.04 LTS didn't work when I pasted it into the special file that you just mentioned: /etc/rc.local (before the exit 0). Is there any reason why it doesn't work in Trisquel 7.0?

My root daemon:
#!/bin/sh -e

while true
do
echo "$(cat /home/a/dim_value)" > /sys/class/backlight/intel_backlight/brightness
sleep 5
done

exit 0

{This way is convenient since all I have to do is execute a script (non-sudo) to change the value in /home/a/dim_value, and the root daemon will echo whatever the contents of this file is into /sys/class/backlight/intel_backlight/brightness. In Lubuntu 14.04 it worked prefectly. }

For the brightness shortcut keys to work, I generally do the following:

1. Run acpi_listen

2. Use the problematic key.

3. Watch output of acpi_listen, we want the first new line that pops up,
and first part before the space unless it says "hotkey" (in which case
we would like the full line).

4. Take note of the interesting part of the message.

5. Press Ctrl + C (terminating acpi_listen).

6. As root, make a shell script in "/etc/acpi", I choose
"acpi-to-nouveau-backlight-brightness.sh", any name is enough, but you
have to remember your custom name later on:

$ sudo nano "/etc/acpi/acpi-to-nouveau-backlight-brightness.sh"

7. Here is the content of my shell script, the things that you will
probably want to change are the ones related to Nouveau (and "nv_"
variables):

# Begin of file
#!/bin/bash

# acpi-to-nouveau-backlight-brightness.sh: Translate ACPI brightness
# to work with Nouveau brightness.
# Copyright © 2017 Adonay "adfeno" Felipe Nogueira <name at domain>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see .

# # Dependencies
#
# - GNU bash is under GNU GPL 3+.
#
# - acpi is under GNU GPL 2+.

declare -A acpi_video
declare -A nv_backlight

acpi_video[path]="/sys/class/backlight/acpi_video0"
nv_backlight[path]="/sys/class/backlight/nv_backlight"

if [[ ! -d "${acpi_video[path]}" && ! -d "${nv_backlight[path]}" ]]
then
exit 1
fi

min_brightness=0
acpi_video[max_brightness]="$(cat "${acpi_video[path]}/max_brightness")"
nv_backlight[max_brightness]="$(cat "${nv_backlight[path]}/max_brightness")"
acpi_video[brightness]="$(cat "${acpi_video[path]}/brightness")"
nv_backlight[brightness]="$(cat "${nv_backlight[path]}/brightness")"

# Needed so that we don't have to watch the ACPI backlight brightness
# every time, and so that the Nouveau backlight brightness matches the
# ACPI one.
nv_backlight[brightness]="$(( ( ${acpi_video[brightness]} * ${nv_backlight[max_brightness]} ) / ${acpi_video[max_brightness]} ))"

# Needed to convert an ACPI backlight brightness step to a Nouveau
# backlight brightness step.
acpi_video_to_nv_backlight_step="$(( ( 1 * ${nv_backlight[max_brightness]} ) / ${acpi_video[max_brightness]} ))"

if [[ "${1}" == "down" ]]
then
nv_backlight[brightness]="$(( ( ( ${acpi_video[brightness]} * ${nv_backlight[max_brightness]} ) / ${acpi_video[max_brightness]} ) - acpi_video_to_nv_backlight_step ))"
elif [[ "${1}" == "up" ]]
then
nv_backlight[brightness]="$(( ( ( ${acpi_video[brightness]} * ${nv_backlight[max_brightness]} ) / ${acpi_video[max_brightness]} ) + acpi_video_to_nv_backlight_step ))"
fi

if [[ "${nv_backlight[brightness]}" -lt "${min_brightness}" ]]
then
nv_backlight[brightness]="${min_brightness}"
elif [[ "${nv_backlight[brightness]}" -gt "${nv_backlight[max_brightness]}" ]]
then
nv_backlight[brightness]="${nv_backlight[max_brightness]}"
fi

echo "${nv_backlight[brightness]}" > "${nv_backlight[path]}/brightness"
# End of file

8. Now, change the script mode so that everyone can read and execute:

$ sudo chmod +rx "/etc/acpi/acpi-to-nouveau-backlight-brightness.sh"

9. Now let's make ACPI events for the brightness keys, you can choose any
name, it doesn't have to be related to the script name. I choose
"acpi-to-nouveau-backlight-brightness-down" and
"acpi-to-nouveau-backlight-brightness-up" for down and up keys,
respectively.

However, if you changed the name of the first script, you have to change
it accordingly in the "event=" line of these "-down" and "-up" files.

$ sudo nano "acpi-to-nouveau-backlight-brightness-down"

# Begin of file
event=video/brightnessdown
action=/etc/acpi/acpi-to-nouveau-backlight-brightness.sh down
# End of file

$ sudo nano "acpi-to-nouveau-backlight-brightness-up"

# Begin of file
event=video/brightnessup
action=/etc/acpi/acpi-to-nouveau-backlight-brightness.sh up
# End of file

10. Make sure that each of these are readable by everyone:

$ sudo chmod +r "acpi-to-nouveau-backlight-brightness-down" "acpi-to-nouveau-backlight-brightness-up"

Happy hacking! :)
--
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