pixelchanged is a simple bash script to detect changes in a region of your screen and execute commands when the change happens.

pixelchanged works in linux (wayland and x11).

Install the dependencies:

On debian based operating systems, install with:

sudo apt install slurp grim awk

On debian based operating system, install with:

sudo apt install imagemagick slop awk

curl -LO https://raw.githubusercontent.com/revelaction/pixelchanged/master/pixelchanged.sh 
# make it executable
chmod +x pixelchanged.sh
# copy it to your path
cp pixelchanged.sh ~/bin

⤷ pixelchanged.sh
Please select a region of the screen
Selected region: 100x101+2346+397. Desktop type: x11

📡 Starting monitoring for changes of the selected region each 10 seconds.

Per default, the script creates a desktop notification when it detects a change in the selected region.

change_handler()
{
    # put commands here that are executed when a change in the pixel happens
    notify_desktop
    # play_sound
}

To play a sound when the selected region changes just substitute the path to a music file in the play_sound function.

play_sound()
{
    check_command "cvlc"
    cvlc --play-and-exit <your-path-to-a-sound-file>.opus
}

and uncomment the call to the function in change_handler

change_handler()
{
    # put commands here that are executed when a change in the pixel happens
    # notify_desktop
    play_sound
}

Modify the script to run arbitrary commands by first creating a bash function:

my_commands()
{
    # my commands
}

Add the function call to the change_handler function:

change_handler()
{
    # put your commands function here 
    my_commands

    # notify_desktop
    # play_sound
}