Schedule to turn off monitor via crontab?

I want to turn off monitor on a specific period of time automatically (for example between 07:00 and 11:00). Is there any command to be set in crontab file? Is there any better way?

In summary:

Turning off the monitor at 07:00 automatically.

Turning on the monitor at 11:00 automatically.

• scren-saver & lock screen are disabled!

Solution 1:

Assuming that you are using the default gnome-screensaver for Ubuntu, open a terminal and run next commands followed by instructions:

1. mkdir -p bin - this command will make a bin directory in your home folder if you don't already have it.
2. gedit ~/bin/screen_on_or_off.sh - this will create the new file screen_on_or_off.sh in gedit.

3. Copy and paste the next script:

   #!/bin/bash
   
   export DISPLAY=:0 #very important if you want to be runned by a cron job
   
   current_hour=$(date +"%k")
   
   # Defining the disable_screensaver function
   function disable_screensaver {
       # Disabling sleep time
       # 0 value will never turn the screen off; you can change this value as you wish:
       # for example to turn the screen of after 10 min, use 600
       gsettings set org.gnome.settings-daemon.plugins.power sleep-display-ac 0
       gsettings set org.gnome.settings-daemon.plugins.power sleep-display-battery 0
       gsettings set org.gnome.desktop.session idle-delay 0
   }
   
   # Defining the enable_screensaver function
   function enable_screensaver {
       # Enabling sleep time to 1 second
       gsettings set org.gnome.settings-daemon.plugins.power sleep-display-ac 1
       gsettings set org.gnome.settings-daemon.plugins.power sleep-display-battery 1
       gsettings set org.gnome.desktop.session idle-delay 1
   
       notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "Let's go to sleep now!"
   }
   
   if [ "$current_hour" -ge "7" ] && [ "$current_hour" -lt "11" ]; then
       enable_screensaver
   else
       disable_screensaver
   fi
   
   exit 0
   

4. Save the file and close it.

5. Go back into terminal and run: chmod +x screen_on_or_off.sh - to grant execute access for the script.
6. Just for test, to run your new script, type in terminal ~/bin/screen_on_or_off.sh.

7. Edit the crontab entries using crontab -e command (by default this will edit the current logged-in users crontab) and add the following line:

   */1 * * * * /home/$USER/bin/screen_on_or_off.sh  #change $USER with your username
   

   I have set the cron job for every minute, but you can change as you wish or as you think is better. See http://en.wikipedia.org/wiki/Cron in this sense.

8. Save the file and check the new crontab entry with crontab -l.

Now your screen will turn off every day between 7 and 11.

Solution 2:

Newer and much simpler answer, put this in cron:

0 07 * * *  export DISPLAY=:0 && xset dpms force off
0 11 * * *  export DISPLAY=:0 && xset dpms force on