This script periodically kills firefox or chromium processes when idle timeout occurs in order to prevent device overheat or overuse of NUC resources (memory)

idle-cleanup.sh

#!/bin/bash
# author Andrej Vitez
# This script is used as a cronjob on Ubuntu 16 on Intel NUC / Compute Stick connected to TV 
# as a media center. The idea is to periodically kill firefox or chromium processes in order to prevent device 
# overheat or overuse of NUC resources (memory). In case if someone is watching a long movie script 
# will show a GUI timeout dialog so the user can abort. Similar to when a TV goes to sleep.
#
# IMPORTANT!
# run the script by dbus-launch to configure dbus session needed by script
# EXAMPLE: $ dbus-launch --sh-syntax --exit-with-session SCRIPT_PATH
# 

# make sure the long process names won't get trimmed
COLUMNS=160
# use default display
export DISPLAY=:0

# export env vars for gksudo to work
# eval $(dbus-launch --sh-syntax --exit-with-session)

# export Xauthority if you have problems opening display from cron script. 
# Replace $USER with user that has desktop environment.
# export XAUTHORITY=/home/$USER/.Xauthority

echo "*** Starting idle-cleanup job at $(date)"

# first check if we have something to clean, we are looking for firefox or chromium processes
pids_firefox=$(pgrep -f firefox/firefox)
pids_chromium=$(pgrep -f chromium)

if [[ -z "${pids_firefox// }" ]] && [[ -z "${pids_chromium// }" ]]; then
        echo "nothing to clean"
        exit 0
fi

# find idle time (no mouse or user activity)
time_offset=$(( 3 * 60 * 60 * 1000 )) # 3 hrs innactivity
idle_time=$(xprintidle)

if [ "$?" -ne 0 ]; then
        (>&2 echo 'Error while retrieving idle time')
        exit 1
fi

if [ "$idle_time" -lt $(( 3 * 60 * 60 * 1000 )) ]; then
        echo "Was active in last three hours, skipping ($idle_time)"
        exit 0
fi

# show GUI user a simple question dialog to abort the cleanup job
zenity --question --timeout 60 \
        --text="Idle-cleanup job was triggered.\n\nPress no to abort or wait 60 seconds to start cleanup." \
         2> /dev/null

case "$?" in
         0|5)
                echo "Executing cleanup..."
                ;;
         1)
                echo "Cleanup canceled by user"
                exit 0
                ;;
         *)
                (>&2 echo "An unexpected error has occurred.")
                exit 1
                ;;
esac

# kill firefox processes
if [[ ! -z "${pids_firefox// }" ]]; then
        for PID in "$pids_firefox"; do
                echo "killing firefox pid $PID"
                kill $PID
        done
fi

# kill chromium processes
if [[ ! -z "${pids_chromium// }" ]]; then
        for PID in "$pids_chromium"; do
                echo "killing chromium pid $PID"
                kill $PID
        done
fi

echo "Job finished at $(date)"