Ubuntu – Schedule to turn off monitor via crontab

cronmonitorshutdown

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!

Best Answer

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

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

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

Save the file and close it.
Go back into terminal and run: chmod +x screen_on_or_off.sh - to grant execute access for the script.
Just for test, to run your new script, type in terminal ~/bin/screen_on_or_off.sh.
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.
Save the file and check the new crontab entry with crontab -l.

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

Related Solutions

Ubuntu – How to turn off the laptop screen while using an external monitor

Find the Name of displays by run xrandr in terminal(your laptop screen is something like LVDS1, and your external monitor is some thing like VGA).

# turn off laptop screen
xrandr --output LVDS1 --off

If you need to turn on the laptop screen::

# laptop screen on
xrandr --output LVDS --mode 1280x800

If you want to turn off external screen::

xrandr --output VGA --off

Ubuntu – How to lock without turning the screen (monitor) off

If you need or want a solution that prevents the screen to fall asleep, but that does dim/lock the screen after a while, there is another solution: instead of the system's own dim/lock option, use the script below to run in the background. You will need to install xprintidle.

How to set up:

Disable all dim / lock options in System Settings. (In Brightness & lock AND in "Energy" settings)
install xprintidle:
```
sudo apt-get install xprintidle
```
Find your screen name; run in a terminal:
```
xrandr
```
Look for the name in the line where it says "connected". Your screen name could be for example VGA-1 or DVI-I-1.
Copy the script below, set the correct screen_name, the idle time before it should lock/dim the screen, and paste it into an empty file. Save it aslock_dim.py

The script

#!/usr/bin/env python3

import subprocess
import time

seconds = 600 # number of seconds to wait before lock/dim the screen
screen_name = "DVI-I-1" # example, replace it with your screen's name

awake = True

while True:
    curr_idle = subprocess.check_output(["xprintidle"]).decode("utf-8").strip()
    if awake == True:
        if int(curr_idle) > seconds*1000:
            command1 = "gnome-screensaver-command -l"
            command2 = "xrandr --output "+screen_name+" --brightness 0.1"
            subprocess.call(["/bin/bash", "-c", command1])
            subprocess.call(["/bin/bash", "-c", command2])
            awake = False
        else:
            pass
    elif awake == False:
        if int(curr_idle) > seconds*1000:
            pass
        else:
            command3 = "xrandr --output "+screen_name+" --brightness 1"
            subprocess.call(["/bin/bash", "-c", command3])
            awake = True
    time.sleep(2)

Test the script by opening a terminal and type:

python3 /path/to/lock_dim.py

If it works as you like, add it to your startup applications: Open Dash > "Startup Applications" > "Add", add the command:

python3 /path/to/lock_dim.py

Best Answer

Related Solutions

Ubuntu – How to turn off the laptop screen while using an external monitor

Ubuntu – How to lock without turning the screen (monitor) off

Related Question