Correct my LCD brightness bash script!

rent0n · 2009-12-01 19:59:58

Hi there

I'm trying to write a script to control my LCD brightness because Arch always set it to 70% or so at startup.
I would like to have full brightness when the AC adapter is present and to have a decrease in brightness when I'm running on battery.

It seems to work quite well but I would like to have suggestions on how to improve it because I have not bash scripting / programming skills at all!

#!/bin/bash

if cat /proc/acpi/ac_adapter/ACAD/state | grep on-line
then
    echo 9 | sudo tee /sys/class/backlight/acpi_video0/brightness
    echo 9 | sudo tee /sys/class/backlight/acpi_video1/brightness
    echo 9 | sudo tee /sys/devices/virtual/backlight/acpi_video0/brightness
    echo 9 | sudo tee /sys/devices/virtual/backlight/acpi_video1/brightness
    echo 100 | sudo tee /proc/acpi/video/GFX0/DD03/brightness
    echo 100 | sudo tee /proc/acpi/video/GFX0/DD04/brightness
    xbacklight -set 100
    exit 0
else
    echo 4 | sudo tee /sys/class/backlight/acpi_video0/brightness
    echo 4 | sudo tee /sys/class/backlight/acpi_video1/brightness
    echo 4 | sudo tee /sys/devices/virtual/backlight/acpi_video0/brightness
    echo 4 | sudo tee /sys/devices/virtual/backlight/acpi_video1/brightness
    echo 40 | sudo tee /proc/acpi/video/GFX0/DD03/brightness
    echo 40 | sudo tee /proc/acpi/video/GFX0/DD04/brightness
    xbacklight -set 40
    exit 1
fi

What do you think of it? Maybe it's too redundant?
Give me your feedback! Thanks!

Last edited by rent0n (2009-12-01 20:00:59)

jelly · 2009-12-01 22:05:48

echo 4 | sudo tee /sys/class/backlight/acpi_video0/brightness
Can't you replace that with:

echo 4 > sudo tee /sys/class/backlight/acpi_video0/brightness

fsckd · 2009-12-01 22:20:22

rent0n wrote:

What do you think of it? Maybe it's too redundant?
Give me your feedback! Thanks!

Yes, I would use functions.

#!/bin/bash

backlight()
{   # usage: backlight int
    local files=(
        /sys/class/backlight/acpi_video0/brightness
        /sys/class/backlight/acpi_video1/brightness
        /sys/devices/virtual/backlight/acpi_video0/brightness
        /sys/devices/virtual/backlight/acpi_video1/brightness
    )
    echo $1 | sudo tee ${files[@]}
}

video()
{   # usage: video int
    local files=(
        /proc/acpi/video/GFX0/DD03/brightness
        /proc/acpi/video/GFX0/DD04/brightness
    )
    echo $1 | sudo tee ${files[@]}
}

if cat /proc/acpi/ac_adapter/ACAD/state | grep -q on-line
then
    backlight 9
    video 100
    xbacklight -set 100
    exit 0
else
    backlight 4
    video 40
    xbacklight -set 40
    exit 1
fi

I haven't tested this nor can I comment on the brightness interface stuff.

Edit 2: I would remove the sudoes and call the whole script using sudo.

Edit:

jelly wrote:

echo 4 | sudo tee /sys/class/backlight/acpi_video0/brightness
Can't you replace that with:
echo 4 > sudo tee /sys/class/backlight/acpi_video0/brightness

No, sudo is a command, not a file.

Last edited by fsckd (2009-12-01 22:26:13)

fsckd · 2009-12-01 22:36:29

Ugh, my network is not great today.

Anyways, two links that can help you in learning bash:

http://tldp.org/LDP/Bash-Beginners-Guide/html/

http://tldp.org/LDP/abs/html/

Edit: Explanation of my changes above.

I added two functions, backlight and video which each take a single argument (I believe should be an integer). The files are listed as arrays using the array_var=( item1 item2 ... itemn ) syntax. This allows for using the array as arguments to a command thanks to array expansion, like so, command ${array_var[@]}. Finally I added -q to the grep to silence it. See grep's manual for more scintillating options. Hope that helps.

Last edited by fsckd (2009-12-01 22:45:14)

Gen2ly · 2009-12-02 07:34:32

Does acpid still work? I tried to start the daemon and get (yeah, put it before hal,dbun in the daemon array):

acpid: can't open /proc/acpi/event: Device or resource busy

The reason I talk about this is because acpid is used for power management events and it may be able to be used for mapping to your brightness keys. If that doesn't work you can use xbindkeys. If that isn't enough, a udev event can be created that detects when your battery is plugged in/out and trigger an event.

rent0n · 2009-12-02 11:34:06

@fsckd: thank you very much for your help, this would definitely improve my script. However, it sounds a bit more complicated to me now. I really would like to learn bash scripting, if only I have enough time!

@Gen2ly: Well, actually, my brightness keys are working perfectly. The problem was just to set the default brightness level at startup because arch always sets it to 70% or so.

NeoXP · 2009-12-02 21:25:16

Don't know if it is of any use to you, but I'm using acpid to handle this. The part regarding screen brightness is handled in the following part of my handler.sh:

    ac_adapter)
        if [ `awk '{print $2}' /proc/acpi/ac_adapter/C1E8/state` == "off-line" ];
        then
            logger "AC Adapter disconnected"
            echo 7 > /sys/class/backlight/acpi_video0/brightness
        else
            logger "AC Adpater connected"
            echo 10 > /sys/class/backlight/acpi_video0/brightness
        fi
    ;;

This works quite well for me.

rent0n · 2009-12-02 22:11:28

NeoXP wrote:

Don't know if it is of any use to you, but I'm using acpid to handle this. The part regarding screen brightness is handled in the following part of my handler.sh:
    ac_adapter)
        if [ `awk '{print $2}' /proc/acpi/ac_adapter/C1E8/state` == "off-line" ];
        then
            logger "AC Adapter disconnected"
            echo 7 > /sys/class/backlight/acpi_video0/brightness
        else
            logger "AC Adpater connected"
            echo 10 > /sys/class/backlight/acpi_video0/brightness
        fi
    ;;
This works quite well for me.

Well this is interesting...Acpid is probably the best way to handle these issues.
I can't understand what the "logger" part is doing, can you please explain it?

Last edited by rent0n (2009-12-02 22:12:06)

NeoXP · 2009-12-02 22:20:21

rent0n wrote:

NeoXP wrote:
Don't know if it is of any use to you, but I'm using acpid to handle this. The part regarding screen brightness is handled in the following part of my handler.sh:
...
This works quite well for me.
Well this is interesting...Acpid is probably the best way to handle these issues.
I can't understand what the "logger" part is doing, can you please explain it?

It logs the text between the quotes in my messages.log and in my everything.log. If something goes wrong on my system it helps me find clues.

rent0n · 2009-12-03 17:35:38

NeoXP wrote:

It logs the text between the quotes in my messages.log and in my everything.log. If something goes wrong on my system it helps me find clues.

I was thinking that your solution should work well when you switch between ac and battery power, however it shouldn't handle LCD brightness at startup, when you boot your laptop, because no acpi event is triggered. Am I wrong?
In my case, I want to set the correct brightness level when I power up my laptop and, for this reason, I placed my script in my autostarted program list. Xfce-power-manager already reduces screen brightness when I switch from ac to battery power.

NeoXP · 2009-12-05 15:53:39

rent0n wrote:

I was thinking that your solution should work well when you switch between ac and battery power, however it shouldn't handle LCD brightness at startup, when you boot your laptop, because no acpi event is triggered. Am I wrong?
In my case, I want to set the correct brightness level when I power up my laptop and, for this reason, I placed my script in my autostarted program list. Xfce-power-manager already reduces screen brightness when I switch from ac to battery power.

I think you're right, there is no difference in brightness if I boot plugged or unplugged. Your script is indeed a good idea to set brightness at boot time.

Thx.

Arch Linux

#1 2009-12-01 19:59:58

Correct my LCD brightness bash script!

#2 2009-12-01 22:05:48

Re: Correct my LCD brightness bash script!

#3 2009-12-01 22:20:22

Re: Correct my LCD brightness bash script!

#4 2009-12-01 22:36:29

Re: Correct my LCD brightness bash script!

#5 2009-12-02 07:34:32

Re: Correct my LCD brightness bash script!

#6 2009-12-02 11:34:06

Re: Correct my LCD brightness bash script!

#7 2009-12-02 21:25:16

Re: Correct my LCD brightness bash script!

#8 2009-12-02 22:11:28

Re: Correct my LCD brightness bash script!

#9 2009-12-02 22:20:21

Re: Correct my LCD brightness bash script!

#10 2009-12-03 17:35:38

Re: Correct my LCD brightness bash script!

#11 2009-12-05 15:53:39

Re: Correct my LCD brightness bash script!

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