I would like to activate a cron job valid for specific users only (for my kids) that it will check if the kids use the pc more than e.g. 60 min per day and then poweroff system. This means that if the condition is true, pc shuts down and in case the user reboots then he/she is not able to login again.
Thank you in advance.
You can add to run at start up for those specific users the following script (which is very close to this one here):
#!/bin/bash
#timelimit - Set daily time limits for a user
#Licensed under the standard MIT license:
#Copyright 2013 Radu Rădeanu (https://askubuntu.com/users/147044/).
#Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
#The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
#THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE
export DISPLAY=:0
time_to_play_daily="0:60:00" # channge as you wish; the format is: H[:M[:S]]
file="$HOME/.count_time"
if [ -a $file ]; then
if [ "$(head -1 $file)" != "$(date +%D)" ]; then
echo $(date +%D) > $file
echo $time_to_play_daily >> $file
fi
else
touch $file
echo $(date +%D) >> $file
echo $time_to_play_daily >> $file
fi
time_to_play_left=$(sed -n '2p' $file)
sec_left=$(echo $time_to_play_left | awk -F: '{ print ($1 * 3600) + ($2 * 60) + $3 }')
function countdown
{
sec_left=$(echo $time_to_play_left | awk -F: '{ print ($1 * 3600) + ($2 * 60) + $3 }')
local start=$(date +%s)
local end=$((start + sec_left))
local cur=$start
while [[ $cur -lt $end ]]; do
cur=$(date +%s)
sec_left=$((end-cur))
time_to_play_left="$((sec_left/3600)):$(((sec_left/60)%60)):$((sec_left%60))"
sed -i "2s/.*/$time_to_play_left/" $file
sleep 1
done
}
if [ $sec_left -gt 0 ]; then
notify-send -i "Time left to play for today: $time_to_play_left"
else
notify-send -i "error" "Your time to play has finished for today!"
sleep 3
fi
countdown $time_to_play_left
sudo poweroff
# or, only for logout you can use:
# gnome-session-quit --logout --no-prompt
Don't forget to make it executable:
chmod +x script_name
Important:
sudo poweroff).
