Thank you for writing brightnessctl. It's fills a gap xbacklight left with issues that haven't been addressed in a while.

This isn't really an issue, but I didn't know where else to write. I wrote a simple frontend for brightnessctl in Python 3, called simplebrightness. It's very basic but it solves the need for those who want a simple frontend. I plan on adding the ability to switch across displays, and maybe switch between preferred intensities, in future updates. All while keeping it simple, as the name goes.

You can find the frontend at:
https://github.com/javiercordero/simple-brightness

brightnessctl g prints absolute value. Is it possible to get percentage?

Documentation: http://man7.org/linux/man-pages/man3/mkdtemp.3.html

When trying to install brightnessctl on gentoo I get:
`chinh4thepro@pog ~/Downloads/brightnessctl-master $ sudo ./configure && make install
Build configuration:

PREFIX: /usr/local
MODE: 0755
UDEV_DIR: /lib/udev/rules.d

udev: enabled
logind: disabled [auto]
install -d /lib/udev/rules.d
install -m 0644 90-brightnessctl.rules /lib/udev/rules.d
install: cannot create regular file '/lib/udev/rules.d/90-brightnessctl.rules': Permission denied
make: *** [Makefile:25: install_udev_rules] Error 1`

How could I fix this?

Hi!

I'm using brightnessctl through the nix store, and for some reason I have no changes to keyboard lightning with the above command:

[2022-01-29 09:49:10] 0 x10an14@bits-laptop:~
-> $ brightnessctl --device='tpacpi::kbd_backlight' g
2
[2022-01-29 09:50:23] 0 x10an14@bits-laptop:~
-> $ brightnessctl --device='tpacpi::kbd_backlight' --min-value
Device 'tpacpi::kbd_backlight' of class 'leds':
	Current brightness: 2 (100%)
	Max brightness: 2

[2022-01-29 09:50:25] 0 x10an14@bits-laptop:~
-> $ brightnessctl --device='tpacpi::kbd_backlight' s 0
Updated device 'tpacpi::kbd_backlight':
Device 'tpacpi::kbd_backlight' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 2

[2022-01-29 09:50:30] 0 x10an14@bits-laptop:~
-> $ brightnessctl --device='tpacpi::kbd_backlight' --min-value
Device 'tpacpi::kbd_backlight' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 2

[2022-01-29 09:50:33] 0 x10an14@bits-laptop:~
-> $

Any suggestions/ideas how to debug this further? Potentially even fix it?

Usually versions of software are matched by the following regex:

^(\d+\.)?(\d+\.)?(\*|\d+)$

Some software/system can be depending on such regex, so different characters can create problems. Please avoid using them.

It seems that unlike light, brightnessctl auto saves the brightness value (the man page does not suggest this). Where is this value saved for persistence and is it possible to prevent this? I would like to manage brightness levels myself based on conditions.

The problem is when I boot the machine, the laptop has some brightness level before I login, then when I login brightnessctl sets its brightness level, and then I have the brightness set myself via a systemd user unit script on login or whatever. I want to avoid brightnessctl implicitly restoring brightness levels which will get replaced anyway after (and to avoid potential race condition).

I'm trying to use --min-value in order to keep something like brightnessctl set 5%- from turning my screen off. However it seems that setting --min-value is preventing ANY change from happening, even if it is above the minimum specified.

~
❯ brightnessctl set 10000
Updated device 'intel_backlight':
Device 'intel_backlight' of class 'backlight':
	Current brightness: 10000 (10%)
	Max brightness: 96000


~
❯ brightnessctl --min-value 5000 set 7000
Device 'intel_backlight' of class 'backlight':
	Current brightness: 10000 (10%)
	Max brightness: 96000


~
❯ brightnessctl --min-value 5000 set 1%-
Device 'intel_backlight' of class 'backlight':
	Current brightness: 10000 (10%)
	Max brightness: 96000


~
❯ brightnessctl --min-value 5000 set 1%+
Device 'intel_backlight' of class 'backlight':
	Current brightness: 10000 (10%)
	Max brightness: 96000


~
❯ brightnessctl --min-value 5000 set 11000
Device 'intel_backlight' of class 'backlight':
	Current brightness: 10000 (10%)
	Max brightness: 96000

I noticed on my machine when setting a percentage, that there is an issue in rounding the absolute value. This is what happens when I try to set the brightness to 25%:

$ sudo ./brightnessctl set 25%
Updated device 'intel_backlight':
Device 'intel_backlight' of class 'backlight':
	Current brightness: 47 (24%)
	Max brightness: 189

This happens on current master (commit d0200a1).

When reviewing the source code, I found that this happens because in the apply_value function the value is calculated with val->val / 100.0 * d->max_brightness. This causes problems since setting to e.g. 25% means 0.25 * 189 = 47.25 gets rounded down to 47.
When the print_device function now calculates the percentage from that 47 again (which also gets always rounded down), the percentage will be 47/189 =0.24867725 which will be rounded down to 24%.

It's possible to change either the calculation in apply_value or print_device, but I would suggest changing the calculation in apply_value, because as a user when setting the brightness to 25%, I would want it to be at least 25%.

EDIT:
I added a pull request (#13) that fixes the issue.

The new output when I try to set the brightness to 25%:

$ sudo ./brightnessctl set 25%
Updated device 'intel_backlight':
Device 'intel_backlight' of class 'backlight':
	Current brightness: 48 (25%)
	Max brightness: 189

Greetings! brightnessctl has shown itself to be the instant solution to regaining control over my native monitor's brightness [via dimmer key (F1) and brighter key (F2)] on my 2019 iMac desktop. I access it easily through keybindings I added within my wmi3 config file.

PROBLEM: I cannot get my 2011 MacBookPro to respond at all ... nor can I get my Dell OptiPlex 7200 to respond ... yet all three are running identical setups, i.e., the same Zen kernel 6.1.6, EndeavourOS, i3, etc.

The difference I detect is that the device 'acpi_video0' is listed via brightnessctl -l on the iMac but there is nothing comparable on the other two platforms (other led devices but not a monitor). In short, I can't seem to find the monitor(s) in the device listings as shown by brightnessctl.

Any thoughts on why? ... and how I might get brightnessctl to recognize the monitor device equivalents on the others?

Hi,

I've been using brightnessctl with systemd integration enabled for a little while, and everything seems to work okay.

I'd like to pick up packaging this for Fedora 31 (as mentioned on #31 ), but ideally would prefer for that package to make use of the new systemd integration, rather than setuid or udev rules. Since it seems that people prefer to have packages built against "released" versions of upstream, would it be okay to bump the version and cut a new release?

I did sudo apt install brightnessctl, but it seems for Ubuntu 20 LTS that although udev rules get copied to /lib/udev/rules.d/ as desired in the debian install routine, it is not possible to use brigthnessctl without sudo.

brightnessctl.c: In function 'apply_operation':
brightnessctl.c:208:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (!p.quiet) {
      ^
brightnessctl.c:213:2: note: here
  fail:
  ^~~~

https://builds.sr.ht/job/221#task-sanity-check-214

It would be great and doable. It would require a daemon, let's call it brightnessd running in root (or whatever user allowed to access the device) listening on DBus and allowing a commands only if the user have an active session connected to a seat.

I am not sure how we could somehow attach the backlight to a specific seat, so it would at first probably allow any user connected to any seat.

What do you think ?

I am open to try and create the needed changes.

Note: logind documentation
It would also probably require systemd

Version has been bumped to 0.3. Let's also add a git tag and create a github release:

https://github.com/Hummer12007/brightnessctl/releases

OS: Arch Linux x86_64
Host: UX390UAK 1.0
Kernel: 4.18.5-arch1-1-ARCH

Udev rules

ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="leds", RUN+="/bin/chgrp input /sys/class/leds/%k/brightness"
ACTION=="add", SUBSYSTEM=="leds", RUN+="/bin/chmod g+w /sys/class/leds/%k/brightness"

/bin/chgrp video /sys/class/backlight/%k/brightness returns
/bin/chgrp: cannot access '/sys/class/backlight/%k/brightness': No such file or directory

/sys/class/backlight is a file, not a directory, and it contains the following (viewed using nvim):

" ============================================================================
" Netrw Directory Listing                                        (netrw v156)
"   /sys/class/backlight
"   Sorted by      name
"   Sort sequence: [\/]$,\<core\%(\.\d\+\)\=\>,\.h$,\.c$,\.cpp$,\~\=\*$,*,\.o$,\.obj$,\.info$,\.swp$,\.bak$,\~$
"   Quick Help: <F1>:help  -:go up dir  D:delete  R:rename  s:sort-by  x:special
" ==============================================================================
../                                                                                                                  
./
intel_backlight@                  --> /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight

The same thing is occurring with the leds "directory". The current workaround is adding <username> ALL=(ALL) NOPASSWD: /bin/brightnessctl to the sudoers file as hinted by the readme.

I am curious why negative delta values has the - sing after the number.

why, n- and n%- instead of -n and -n%

In the README file you say that INSTALL_UDEV_RULES by default is 0 and 1 is to install the udev rules, but in the Makefile the default value is actually 1 and 0 is to install the udev rules. A small thing but bugged when I was changing it to 1 :) .

The link in the README 404s and I can't find anything with apk search brightnessctl.

Where are the packages gone?

Instead of just obtaining the absolute value, maybe it would be nice to extend this and make it possible to obtain a percentage value as well.

I've look around the code, and it seems the easiest way to support this would be to add another operation, say GET_PERCENTAGE in the form of g% which could look something like the following:

$ brightnessctl
Device 'mock_device' of class 'mock_class':
        Current brightness: 127 (50%)
        Max brightness: 255
$ brightnessctl -d mock_device g
127
$ brightnessctl -d mock_device g%
50

I can probably submit a PR and have this working exactly like this. Alternatively, it doesn't have to be g% as that would "mess up" operation matching with an extra if for g. Could be p (for "percentage"), for instance.

Otherwise, looking into extending g itself is also relatively messy and would require more moving parts. In fact, it would look more like s (SET) then, which I find relatively unnecessary.

I'd like to discuss this further. In the meantime, I can test something out using p as the operation, defining GET_PERCENTAGE or GET_PERCENT as another operation type, and submit a PR.

Do you think setting default minimum value to 1 is a good idea?

$ brightnessctl --version
0.5

but the package is supposed to be 0.5.1 (https://archlinux.org/packages/community/x86_64/brightnessctl/).

Command: brightnessctl --restore --quiet (After having saved the previous value)
Expected output: No output at all
Actual output:

Device 'intel_backlight' of class 'backlight':
	Current brightness: 2220 (50%)
	Max brightness: 4438

Hi,

Thanks for your work on brightnessctl.

It would be practical to be able to set the brightness level of all connected monitors.
For example brightnessctl -c backlight s 10+ could set the brightness of all connected "backlight" devices.
I think it's not possible in the current state.

For example in my case I have:

$ ls /sys/class/backlight
amdgpu_bl0  ddcci9

What do you think?

Cheers,
Pierre

PS: I could also wrap brightnessctl with a shell script and run it several times, but ... :)

The link in the README 404s and I can't find anything with apk search brightnessctl.

Where are the packages gone?

Udev rules are not creating when installing brightnessctl from dnf in Fedora 35. But when I compile manually or install it from apt(I tried in Kubuntu), it does.

My laptop is under Software Rendering, and brightnessctl doesn't work for me after I upgraded Ubuntu to Lunar Lobster. Now my laptop shows with maximal brightness value.
The information is following:

$ sudo brightnessctl -l
Available devices:
Device 'input4::capslock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'input12::kana' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'phy0-led' of class 'leds':
        Current brightness: 1 (100%)
        Max brightness: 1

Device 'input12::compose' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'input4::scrolllock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'input12::scrolllock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'input4::numlock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'input12::numlock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'mmc0::' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 255

Device 'input12::capslock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

$ screenfetch 
                          ./+o+-       larry@zx0
                  yyyyy- -yyyyyy+      OS: Ubuntu 23.04 lunar
               ://+//////-yyyyyyo      Kernel: x86_64 Linux 6.1.0-16-generic
           .++ .:/++++++/-.+sss/`      Uptime: 1h 5m
         .:++o:  /++++++++/:--:/-      Packages: 10953
        o:+o+:++.`..```.-/oo+++++/     Shell: bash 5.2.15
       .:+o:+o/.          `+sssoo+/    Resolution: 1920x1080
  .++/+:+oo+o:`             /sssooo.   DE: GNOME 44.alpha
 /+++//+:`oo+o               /::--:.   WM: Mutter
 \+/+o+++`o++o               ++////.   WM Theme: 
  .++.o+++oo+:`             /dddhhh.   GTK Theme: Yaru-red-dark [GTK2/3]
       .+.o+oo:.          `oddhhhh+    Icon Theme: Yaru-red-dark
        \+.++o+o``-````.:ohdhhhhh+     Font: Ubuntu 11
         `:o+++ `ohhhhhhhhyo++os:      Disk: 109G / 234G (49%)
           .o:`.syhhhhhhh/.oo++o`      CPU: ZHAOXIN KaiXian [email protected]+GHz @ 4x 2.6GHz
               /osyyyyyyo++ooo+++/     GPU: llvmpipe (LLVM 15.0.6, 256 bits)
                   ````` +oo+++o\:     RAM: 3572MiB / 23520MiB
                          `oo++.      

$ sudo brightnessctl set 1% ↵
Updated device 'input4::capslock':
Device 'input4::capslock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Hope I could get help.

Regards
larryw3i.

A PR is on the way

Would it be possible to implement an option to transition the fade when setting, ie. brightnessctl set 5%-, so that it's more aesthetically pleasing and feels less clunky as it steps up or down?

It works but i want to ask can i change colors of my keyboard ( now its wave mode ), only able to change brightness level ? , maybe i can change something else

$ brightnessctl -l | head -n 5
Available devices:
Device 'intel_backlight' of class 'backlight':
	Current brightness: 1049 (98%)
	Max brightness: 1060

When I try to change it, nothing at all happens to the display brightness on the laptop (Yoga X1 v2)

$ brightnessctl -d intel_backlight s 50%
Updated device 'intel_backlight':
Device 'intel_backlight' of class 'backlight':
	Current brightness: 530 (50%)
	Max brightness: 1060

It would be great if I could pass fractional percentage values to brightnessctl – e.g., brightnessctl set 0.5%. It looks like all the percentage calculations occur on the FPU anyway, so this could probably be done simply by changing value.val to be a float and using strtof to parse it.

Ubuntu 18.04.
I have one laptop and two external monitors connected.

$ xrandr -q | grep " connected"  
eDP-1 connected (normal left inverted right x axis y axis)  
DP-1-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm  
DP-1-2 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 527mm x 296mm

However, brightnessctl doesn't detect them.

$ brightnessctl -l
Available devices:
Device 'intel_backlight' of class 'backlight':
	Current brightness: 24000 (20%)
	Max brightness: 120000

Device 'input4::capslock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'phy0-led' of class 'leds':
	Current brightness: 1 (100%)
	Max brightness: 1

Device 'input4::scrolllock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'input4::numlock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'dell::kbd_backlight' of class 'leds':
	Current brightness: 1 (50%)
	Max brightness: 2

There is a release 0.2.1, but the version in the Makefile still contains 0.2

works in a terminal or if i run it as program.

or maybe i am missing something.

thanks for your attention.

Output when trying to update:

# make install
echo installing
installing
mkdir -p /usr/local/lib/brightnessctl
cp -R ./*  /usr/local/lib/brightnessctl/
ln -s /usr/local/lib/brightnessctl/writebrightness.sh /usr/local/bin/brightness
ln: failed to create symbolic link '/usr/local/bin/brightness': File exists
makefile:4: recipe for target 'install' failed
make: *** [install] Error 1

If I set the value of intel_backlight to 1199, the % reported is correct:

sudo brightnessctl --device='intel_backlight' set 1199
Updated device 'intel_backlight':
Device 'intel_backlight' of class 'backlight':
    Current brightness: 1199 (100%)
    Max brightness: 1200

However, if I set this with exponant the reported brightness is 0% (I was trying to figure out how it worked at the time, so don't mind my nonsense settings)

sudo brightnessctl --device='intel_backlight' -e=4 set 5%-
Updated device 'intel_backlight':
Device 'intel_backlight' of class 'backlight':
    Current brightness: 1200 (100%)
    Max brightness: 1200
sudo brightnessctl --device='intel_backlight' -e=4 set 5%-
Updated device 'intel_backlight':
Device 'intel_backlight' of class 'backlight':
    Current brightness: 1199 (0%)
    Max brightness: 1200

This makefile is specific to GNU Make

At this moment brightnessctl can't see and manipulate with external monitors. It's would be awesome if brightnessctl will have support of configuring external monitors using DDC/CI (Display Data Channel Command Interface). Now I can do it with the help of ddcutil utility.
Example of ddcutil usage

What do you think about it?
If you have nothing against it, I can tried to implement it.

When I use the XFMonBrightnessDown keybinding for brightnessctl set 10%- either in Ubuntu, XFCE, i3 WM or Qtile WM, the screen briefly flashes (very brightly) before setting the desired brightness level.

This doesn't happen with the XFMonBrightnessUp keybinding for brightnessctl set +10%, and it doesn't happen either when I run the brightnessctl set 10%- directly in the terminal.

Since this doesn't seem to be an issue with Ubuntu, XFCE, i3 or Qtile (they all behave the same though keybindings work in different ways for each), and since it doesn't happen when increasing brightness, I'm inclined to think it's a bug in brightnessctl.

I believe it's not a problem of brightnessctl, but maybe you can help.

➜  ~ brightnessctl s 1
Updated device 'nvidia_0':
Device 'nvidia_0' of class 'backlight':
	Current brightness: 1 (1%)
	Max brightness: 100

at 1% - real screen brightness is looks like 10%

➜  ~ brightnessctl s 10
Updated device 'nvidia_0':
Device 'nvidia_0' of class 'backlight':
	Current brightness: 10 (10%)
	Max brightness: 100

at 10% - real screen brightness is looks like 100%

➜  ~ brightnessctl s 100
Updated device 'nvidia_0':
Device 'nvidia_0' of class 'backlight':
	Current brightness: 100 (100%)
	Max brightness: 100

at 100%- real screen brightness is looks like 50%

for example "11" looks darker then "1".

Device is a Thinkpad with Nvidia graphics.

/sys/class/backlight/nvidia_0/actual_brightness is changing as expected

Any ideas?

Right now when i press ScrollLock (BorolLook) and turn the keyboard backlight LED's on and then press CapsLock the keyboard backlight LED goes off, i'm not sure what is the issue here, but i know that it works correctly on Windows 10/11.

Heres the output of the LED devices:

Available devices:
Device 'acpi_video1' of class 'backlight':
        Current brightness: 48 (98%)
        Max brightness: 49

Device 'acpi_video0' of class 'backlight':
        Current brightness: 5 (10%)
        Max brightness: 49

Device 'input4::capslock' of class 'leds':
        Current brightness: 0 (0%)
        Max brightness: 1

Device 'input4::scrolllock' of class 'leds':
        Current brightness: 1 (100%)
        Max brightness: 1

Device 'input4::numlock' of class 'leds':
        Current brightness: 1 (100%)
        Max brightness: 1

ddcci10 is used for "ddcci*", ddcci9 can be only accessed by it's name

% brightnessctl -c backlight -d "ddcci*" s 0
Updated device 'ddcci10':
Device 'ddcci10' of class 'backlight':
	Current brightness: 0 (0%)
	Max brightness: 100

% brightnessctl -l                           
Available devices:
Device 'ddcci10' of class 'backlight':
	Current brightness: 0 (0%)
	Max brightness: 100

Device 'ddcci9' of class 'backlight':
	Current brightness: 20 (20%)
	Max brightness: 100

Device 'input0::scrolllock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'input0::capslock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'input0::numlock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

v0.5.1-3 debian sid

Could you build and upload Packages for Fedora 30, as it is now released ?
Up until now, the packages are only available on Fedora 28 and 29.

Best
Florian

I am using Sway + Waybar and I have setup my brightness key bindings as follows:

bindsym XF86MonBrightnessDown exec "brightnessctl set 5%-"
bindsym XF86MonBrightnessUp exec "brightnessctl set +5%"

The issue is when starting at a brightness level of 0% and going up it increases by 5% as expected. However, when going from 100% down, it initially goes down to 94% which not is not right as that it a decreased of 6%. What is weird is that after the first decrease it goes returns to normal decreasing by 5%.

So 100%, 94%??, 89% and so on....

A lot of the allocated memory isn't freed, I don't think it's an issue in itself since the program is short lived but it would make tools like valgrind or ASAN happy and thus make potential bugs easier to debug.

I first installed brightnessctl via apt.
But then I could not set the brightness via brightnessctl s +10%. Although brightness-udev (0.5.1-2) is installed.
I than I uninstalled brightnessctl and installed via pip.
When calling brightnessctl now I get an error, that there is no path: /sys/class/backlight/intel_backlight/actual_brightness which is correct because the laptop uses a AMD APU with the path /sys/class/backlichtamdgpu_bl0

How do can I set the brightness, on the system?