Easy timed turns on Linux for kids (automatic logout after timer ends, with 1-minute warning)

timed_session.sh

#!/bin/bash
# Requires:
# 1. at
# 2. espeak or spd-say
# 3. zenity
# 4. notify-send
# 5. MATE or Gnome desktop
talk=$(which espeak || which spd-say)
if [[ "$(which mate-session-save)" != "" ]]; then
    logout="mate-session-save --force-logout"
else
    if [[ "$(which gnome-session-quit)" != "" ]]; then
        logout="gnome-session-quit --no-prompt"
    else
        echo "Unknown desktop error."
        return 1
    fi
fi
# DEBUG
#logout=$talk' "I just logged you out. Ha ha."'

$talk "How many minutes is your turn?"
end=$(zenity --list --title="How long is your turn?" \
             --column="How many minutes is your turn?" \
             --width=500 \
             --height=250 \
             --timeout=30 \
             1 \
             5 \
             10 \
             20 \
             30)

if [ "$end" == "" ]; then
    # It timed out or the user canceled.
    echo $talk' "Boop boop beep." && '$logout | at now
else
    # Calculate warning time.
    warn=$[$end-1]
    echo 'notify-send "1 minute left" "Please save your work now." && '$talk' "One minute warning"' | at now + $warn minutes
    echo $talk' "Your time is up. Goodbye." && '$logout | at now + $end minutes
    $talk "You have '$end' minutes, starting now."
fi
# Done!

Add this script to your Startup Items on your kids' user account(s).