Log user out of Ubuntu session when the sesion duration has been exceeded or total logon time for today has been exceeded.

functions.sh

#!/bin/bash

function current_session_time() {
    # Get the duration of the current logon session in seconds

    username="$1"
    info=$(last -Fn1 $username)
    # Get the current time and the session time in seconds
    current_time=$(date +%s) 
    session_time=$(date -d "$(echo $info | awk '{print $5, $6, $7, $8}')" +%s)

    # Calculate the difference between the current time and the session time
    difference=$((current_time - session_time))
}

function get_time_previous_sessions() {
	# Get the total time of previous logon sessions in seconds.

	username="$1"
	
	info=$(last -F --since today $username)
	# Example output:
	# miguel   tty3         tty3             Sun Jul  7 16:14:53 2024   still logged in
	# miguel   tty3         tty3             Sun Jul  7 14:07:12 2024 - Sun Jul  7 15:03:10 2024  (00:55)
	# miguel   tty3         tty3             Sun Jul  7 14:01:10 2024 - Sun Jul  7 14:06:59 2024  (00:05)
	# miguel   tty3         tty3             Sun Jul  7 09:00:17 2024 - Sun Jul  7 14:00:59 2024  (05:00)

	# Get the time (xx:xx) from each of the following lines
	times=$(echo "$info" | grep -o '([0-9][0-9]:[0-9][0-9])')

	# Calculate the total time in seconds from the session durations
	for time in $times; do
	    hours=$(echo $time | cut -d: -f1)
	    minutes=$(echo $time | cut -d: -f2)
	    total_time=$((total_time + ($hours * 3600) + ($minutes * 60)))
	done
}

logout.sh

#!/bin/bash

function log_user_out() {
    # Notify the user that the session will be logged out
    username="$1"
    export DISPLAY=$username
    export XAUTHORITY=/home/$username/.Xauthority
    export XDG_RUNTIME_DIR=/run/user/$(id -u $username)

    /usr/bin/notify-send 'Je zit te lang op de computer.'
    sleep 3
    # Users still have the option here to cancel the logout
    #gnome-session-quit --logout
    
    # Force user logout
    pkill -SIGKILL -u $(whoami)
}

session_duration.sh

#!/bin/bash
# Log the user out if the current session duration has been exceeded.

# Provide the full path to the functions file, otherwise cron will not find them
source "$HOME"/cron_jobs/logout.sh
source "$HOME"/cron_jobs/functions.sh

#set -x

duration_limit=1800 # 30 minutes
current_session_time $(whoami)
echo $(date -u) "Current session duration: $difference seconds"

# Check if the session duration exceeds the limit
if (($difference > $duration_limit)); then
    echo $(date -u) "Session duration exceeds the limit of 30 minutes"
    # Log the user out
    log_user_out $username
fi

total_sessions_duration_today.sh

#!/bin/bash

# Log the user out if the total login time today has been exceeded.

# Provide the full path to the functions file, otherwise cron will not find them
source "$HOME"/cron_jobs/logout.sh
source "$HOME"/cron_jobs/functions.sh

#set -x

username=$(whoami)
total_time_allowed=3600 # One hour a day allowed

current_session_time $username
get_time_previous_sessions $username
total_time=$((difference + total_time))

echo $(date -u) "Total time logged in today: $total_time seconds"

# Check if the session duration exceeds the limit
if (($total_time > $total_time_allowed)); then
    echo $(date -u) "User has been logged in for more than one hour today."
    # Log the user out
    log_user_out $username
fi