I'm looking for a command to flash screens (if possible in colors)

I'm using the xfce4 timer and I want the alarm to make the screen blink in addition to the pop-up alarm. Currenly I am using

xset dpms force off; sleep 3; xset dpms force on

which lets the screen go off an on again but I would like it to blink with colors and faster if possible in a flashing style

Greetings

1 Answer

I made a bash script to meet the objective:

flash-primary-screen.sh bash script

Copy this bash script to your computer:

#!/bin/bash
# NAME: flash-primary-screen.sh
# PATH: ~/bin
# DESC: Flashes primary screen colours to alert timer has ended.
# DATE: November 15, 2018
# NOTE: Written for:
# I'm looking for a command to flash screens (if possible in colors)
# Change 6 variables below to control screen flashing levels
MaxBright="1.5"
MinBright=".5"
MaxRed="2.0"
MaxGreen="2.0"
MaxBlue="2.0"
MinGamma=".5"
declare aXrandr=()
# Next two functions lifted from: eyesome internet sunrise/sunset time screen
# brightness and gamma controller:
InitXrandrArray () { # Array is used for each monitor and searched by name. # Save time to search on connected/disconnected, primary monitor, # brightness level, gamma level. mapfile -t aXrandr < <(xrandr --verbose --current)
} # InitXrandrArray
SearchXrandrArray () { # Parms: $MonXrandrName = xrandr monitor name to search for. # NOTE: Entries in array follow predicatble order from xrandr --verbose: # <MONITOR-NAME> connected / disconnected (line 1 of monitor entry) # Gamma: 0.99:0.99:0.99 (line 5 of entry) # Brightness: 0.99 (line 6 of entry) # CRTC: 9 (line 8 of entry) fNameFnd=false fBrightnessFnd=false fGammaFnd=false fCrtcFnd=false XrandrConnection=disconnected XrandrPrimary=false XrandrGamma="" XrandrBrightness="" XrandrCRTC="" # Laptop lid open value=0, lid closed=blank for (( i=0; i<"${#aXrandr[*]}"; i++ )) ; do line="${aXrandr[$i]}" # Have we looped to next monitor and not found search string? if [[ "$line" =~ " connected " ]] && [[ $fNameFnd == true ]] ; then break fi if [[ "$line" =~ ^"$MonXrandrName connected" ]]; then fNameFnd=true XrandrConnection=connected [[ "$line" =~ "primary" ]] && XrandrPrimary=true fi if [[ $fNameFnd == true ]] && [[ $fGammaFnd == false ]] ; then if [[ "$line" =~ "Gamma: " ]]; then fGammaFnd=true XrandrGamma="${line##* }" # TODO: Use `xgamma` for accuracy fi fi if [[ $fGammaFnd == true ]] && [[ $fBrightnessFnd == false ]] ; then if [[ "$line" =~ "Brightness: " ]]; then fBrightnessFnd=true XrandrBrightness="${line##* }" fi fi if [[ $fBrightnessFnd == true ]] && [[ $fCrtcFnd == false ]] ; then if [[ "$line" =~ "CRTC: " ]]; then fCrtcFnd=true XrandrCRTC="${line##* }" break fi fi done
} # SearchXrandrArray
FlipBright () { if [[ $NewBrightness == "$MaxBright" ]] ; then NewBrightness="$MinBright" else NewBrightness="$MaxBright" fi
} # FlipBright
CleanUp() { xrandr --output "$MonXrandrName" --gamma "$SaveGamma" \ --brightness "$SaveBrightness" # Compensate for bug in Xrandr as of Nov 15, 2018 with second call InitXrandrArray SearchXrandrArray xrandr --output "$MonXrandrName" --gamma "$XrandrGamma" exit 0
} # CleanUp
Main () { trap CleanUp INT TERM # Get primary monitor current settings XrandrName=$(xrandr --current | grep primary) MonXrandrName="${XrandrName%% *}" InitXrandrArray SearchXrandrArray # Did we find primary monitor ok? if [[ $fBrightnessFnd == false ]] || [[ $fGammaFnd == false ]] ; then echo "Internal Error: Could not find Primary Screen brightness or gamma" echo XrandrPrimary: "$XrandrPrimary" echo aXrandr[0]: "${aXrandr[0]}" echo Brightness: "$XrandrBrightness" echo Gamma: "$XrandrGamma" exit 2 fi # Restore these values when CleanUping program SaveBrightness="$XrandrBrightness" SaveGamma="$XrandrGamma" # Wait for <Ctrl>+C or until parent kills us. while true ; do if [[ $Red == true ]] ; then Red=false Green=true NewGamma="$MaxRed:$MinGamma:$MinGamma" FlipBright elif [[ $Green == true ]] ; then Green=false NewGamma="$MinGamma:$MaxGreen:$MinGamma" FlipBright else Red=true NewGamma="$MinGamma:$MinGamma:$MaxBlue" FlipBright fi xrandr --output "$MonXrandrName" --gamma "$NewGamma" \ --brightness "$NewBrightness" sleep .2 done
} # Main
Main "$@"

Mark the script as executable using:

chmod a+x /path/flash-primary-screen.sh

Where /path is the directory you placed the script.

Call the script from your program (or even the command line). To end the script press Ctrl+C.

Change the first 6 variables defined to manipulate the brightness level and color level changes.

Don't hesitate to ask questions or post suggestions in comment section below!

You can also have color flashing ASCII Art text in the terminal:

Here is the script:

#!/bin/bash
From:
DATA[0]=" _/ _/ _/ _/ "
DATA[1]=" _/_/_/_/_/ _/_/_/ _/_/_/ _/_/_/ _/_/_/ "
DATA[2]=" _/ _/ _/ _/ _/ _/ _/_/ _/ _/"
DATA[3]="_/_/_/_/_/ _/ _/ _/ _/ _/_/ _/ _/ "
DATA[4]=" _/ _/ _/_/_/ _/_/_/ _/_/_/ _/ _/ "
# virtual coordinate system is X*Y ${#DATA} * 5
REAL_OFFSET_X=0
REAL_OFFSET_Y=0
draw_char() { V_COORD_X=$1 V_COORD_Y=$2 tput cup $((REAL_OFFSET_Y + V_COORD_Y)) $((REAL_OFFSET_X + V_COORD_X)) printf %c ${DATA[V_COORD_Y]:V_COORD_X:1}
}
trap 'exit 1' INT TERM
trap 'tput setaf 9; tput cvvis; clear' EXIT
tput civis
clear
while :; do
for ((c=1; c <= 7; c++)); do tput setaf $c for ((x=0; x<${#DATA[0]}; x++)); do for ((y=0; y<=4; y++)); do draw_char $x $y done done
done
done

To generate the ASCII Art you can use Figlet or Toilet. See: When terminal is opened can I get current calendar and time displayed?