Changing wallpaper login screen

Tips, Tricks and Tutorials Tips & Tricks
1

I made a script to easily change the wallpaper of the loginscreen.

It lets the user select an image and set it as the desktop background on Ubuntu MATE. It copies the image to the /usr/share/backgrounds directory, updates the background setting, and recompiles the schemas.

2025-03-21_19-54
2025-03-21_19-54506×266 35.3 KB

#!/bin/bash

# This script lets the user select an image and
# set it as the desktop background on Ubuntu MATE. It copies
# the image to the /usr/share/backgrounds directory,
# updates the background setting, and recompiles the schemas.
# Philippe734 @ 2025

# Check if YAD installed
if ! command -v yad &> /dev/null; then
    pkexec bash -c "apt install yad -y"
fi

yad --title="Change background login screen" --height=150 --width=400 --fixed --text="<span foreground='blue'><b><big><big>Select your image</big></big></b></span>" --text-align=center --center --borders=20 --image='./design.png'

if [ $? = 1 ]; then
    echo "canceled"
    exit 0
fi

DEST_DIR="/usr/share/backgrounds"
SCHEMA_FILE="/usr/share/glib-2.0/schemas/30_ubuntu-mate.gschema.override"

while true; do
    # Let the user select an image
    IMAGE_PATH=$(yad --file --center --title="Select an image" --width=600 --height=400)
    
    # If no image is selected, exit
    test -z "$IMAGE_PATH" && exit 1
    
    # Check if the selected file is an image
    MIME_TYPE=$(file --mime-type -b "$IMAGE_PATH")
    if [[ $MIME_TYPE =~ ^image/ ]]; then
        break  # Exit the loop if the file is a valid image
    else
        yad --title "Error" --width=400 --height=100 --center --button=OK:0 \
            --text "The selected file is not an image. Please select a valid image file."
    fi
done

# Get the file name without modification
IMAGE_NAME=$(basename "$IMAGE_PATH")

# Final path in /usr/share/backgrounds
FINAL_IMAGE_PATH="$DEST_DIR/$IMAGE_NAME"

# Escape the apostrophes in the image path before running pkexec
ESCAPED_IMAGE_PATH=$(echo "$FINAL_IMAGE_PATH" | sed "s/'/'\\\\''/g")

# Call pkexec to execute commands as root
pkexec bash -c "

    # Copy the image and modify the schema
    cp -f \"$IMAGE_PATH\" \"$FINAL_IMAGE_PATH\"

    # Change permissions of the copied image to make it readable by others
    chmod 644 "$FINAL_IMAGE_PATH"

    # Modify the schema file to set the new background image path
    sed -i \"s|^background=.*|background='$ESCAPED_IMAGE_PATH'|\" \"$SCHEMA_FILE\"
    
    # Compile the schemas
    glib-compile-schemas /usr/share/glib-2.0/schemas/
"

# Display the final result
echo "### result:"
grep "^background=" "$SCHEMA_FILE"
echo "###"

notify-send "Done" "You should logout"

exit 0
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