Linux - Screen Control
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12 (bookworm) |
This little setup allows for remote control (via MQTT) of the screen(s) of Linux-based computers.
Specifically set up for all-in-one machines & laptops since these are a little difficult to shut off the screen without shutting down the machine itself.
The Script
sudo apt install vbetool
The following script needs to run as root...
sudo vi /usr/local/bin/screenremote.py
#!/usr/bin/env python
import paho.mqtt.client as mqttClient
import time
import os
import subprocess
import socket
###################################################################################################
hostname = socket.gethostname()
broker_address = "skynet"
port = 1883
topic = hostname + "/#"
user = "user"
password = "password"
client = mqttClient.Client(hostname + "control")
client.username_pw_set(user, password=password)
###################################################################################################
## Broker Connection ##
###################################################################################################
Connected = False
def on_connect(client, userdata, flags, rc):
global Connected
if rc == 0:
print(" HostName: ", hostname)
print("Connected to broker: ", broker_address)
print(" Subscribed to: ", topic)
print()
Connected =True
else:
print("Connection failed")
Connected =False
###################################################################################################
## Message Handling ##
###################################################################################################
def on_message(client, userdata, message):
print( " Received message: " + str(message.payload.decode("utf-8")))
print( " on topic: " + message.topic)
#print( " with QoS: " + str(message.qos))
time.sleep(1)
### Display control (turn the screen on or off...)
if message.topic == hostname + "/display":
command = "/usr/sbin/vbetool dpms " + str(message.payload.decode("utf-8"))
print( command )
os.system(command)
### Audio control (something for th future...)
elif message.topic == hostname + "/audio":
print("audio stuff")
### Not any sort of valid topic...
else:
print("Not Important to us...")
print()
###################################################################################################
client.on_connect = on_connect
client.on_message = on_message
client.connect(broker_address, port=port)
client.loop_start()
while Connected != True:
time.sleep(0.1)
client.subscribe(topic)
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
print( "exiting" )
client.disconnect()
client.loop_stop()
sudo chmod +x /usr/local/bin/screenremote.py
This will respond to MQTT messages:
- HOSTNAME/display on
- HOSTNAME/display off
The Service
It works as a systemd service
sudo vi /etc/systemd/system/remote-screen-control.service
[Unit]
Description=Watch for MQTT messages to turn screen on/off
Documentation=https://wiki.nerdmage.ca/index.php/Linux_-_Screen_Control
After=multi-user.target network.target
[Service]
ExecStart=<code>/usr/local/bin/screenremote.py</code>
Type=simple
Restart=on-failure
[Install]
WantedBy=multi-user.target
sudo systemctl daemon-reload
sudo systemctl enable remote-screen-control.service
sudo systemctl start remote-screen-control.service
sudo systemctl status remote-screen-control.service
Notes
non vbetool capable systems
For some systems, vbetool fails.
In this case, if the system has X installed (i.e.: it has a GUI), xset might do the job in its place.
xset -display :0.0 dpms force off
xset -display :0.0 dpms force on
As of yet... No solution for systems without X.
Python Weirdness
Sometimes, Python & it's tools & modules are a little problematic.
Installing Python3 & paho-mqtt directly will force this to work. (&, of course, you should force it to be Python3...)
sudo apt install python-is-python3 python3-paho-mqtt