[TUTORIAL] Sharing information between BASH and Gladys

Tutorials
2

TUTORIAL No.2: Run a BASH command via a Gladys action.
The idea is to monitor a Gladys device topic from BASH and execute the appropriate commands.

Gladys side:

  1. Device creation:
    Name : Appel BASH
    External ID : mqtt:Salle:AppelBASH
    Room : Salle

  2. Add a feature of type Button Click (for example):
    Name : Appel BASH
    Feature external ID : mqtt:AppelBASH:Action
    Min value : 0
    Max value : 9 (Allows 10 different actions)
    Keep state history : Yes
    Is it a sensor : No
    MQTT topic to listen to : You can note the topic that will be used later.

  3. Define a scene:
    Trigger : One of your choice (such as the state change of a real button, for example).
    Action : Control a device.
    Device : Appel BASH
    Value : 1 (between 0 and 9)

You will only need to trigger the scene once the BASH scripts are finished.

BASH scripts.

  1. Reuse the common script /opt/mosquitto/MQTTConfig.sh from TUTORIAL No.1.

  2. Create the script /opt/mosquitto/GladysToBash.sh :
    It will listen to the topic of the device created in Gladys.

#!/bin/bash

#####################################################################
## Monitoring a Gladys topic with execution of BASH commands ##
#####################################################################

### Variables to customize
# You must customize the CASE in the WHILE loop.

# Device topic address
# Available in Gladys > Integration > MQTT > Devices > Appel BASH > Button Click > MQTT topic to listen to
Topic="gladys/device/mqtt:salle:AppelBASH/feature/mqtt:AppelBASH:Action/state"
### Variables to customize

# Load the common file
source /opt/mosquitto/MQTTConfig.sh

# Requires the mosquitto_sub command from the mosquitto-clients package
! CommandCheck "mosquitto_sub:mosquitto-clients" \u0026\u0026 exit 1

echo "Le script attend de recevoir les commandes de Gladys." 1\u003e\u00262
echo "Il ne rend la main que si des break et exit sont intégrés à la boucle while." 1\u003e\u00262

# Loop continuously listening to the Gladys device topic
# -u User : User for connecting to the MQTT broker, comes from MQTTConfig.sh
# -P Pass : Password for connecting to the MQTT broker, comes from MQTTConfig.sh
# -t Topic : Address of the Topic of the device created in Gladys, defined at the beginning of the script
# Capture the returns into the variable Value
while read Value
do
    # Skip processing if Value is not between 0 and 9
    if [[ "${Value}" != [0-9] ]]
    then
        echo -e "[${ORANGE}Attention${RAZ}] Valeur ${Value} inconnue..." 1\u003e\u00262
        continue
    fi

    echo -e "[${FUCHSIA}$(date +'%x %X')${RAZ}] Exécution de la commande n°${Value}."

    # Case to perform the correct action depending on Value
    # Use of echo to avoid actually executing the commands in this TUTORIAL
    case "${Value}" in
        # Reboot the Raspberry
        0) echo sudo reboot ;;

        # Wake up a PC via WakeOnLan in the background so as not to block the loop
        1) echo wakeonlan XX:YY:ZZ:ZZ:YY:XX \u0026 ;;

        # Start an alarm via a wav file in vlc in the background so as not to block the loop
        2) echo vlc "/opt/alarme.wav" \u0026 ;;

        # Kill all vlc commands
        3) echo killall vlc ;;

        # Any other actions of your choice...
        [3-9]) echo "Réalisation de l'action ${Value}.";;
    esac
done \u003c \u003c(mosquitto_sub -u "${User}" -P "${Pass}" -t "${Topic}")

You must adapt the variables between ### Variables to customize as well as the actions in the case of the while loop.

For information, it is possible to specify the number of messages expected by mosquitto_sub before it returns control:

mosquitto_sub -u "${User}" -P "${Pass}" -t "${Topic}" -C x # Where x is the number of messages
  1. Script execution:

Just call the script with a simple:

bash /opt/mosquitto/GladysToBash.sh

The script does not return control to the prompt, this is normal; the loop is infinite.
It displays:

The script is waiting to receive commands from Gladys.
It only returns control if break and exit are integrated into the while loop.

  1. Executing the desired scene from Gladys:

Nothing special here; just execute the scene manually or via another device.
The shell then displays:

[16/02/2023 11:35:05] Execution of command No.5.
[16/02/2023 11:35:55] Execution of command No.2.
[16/02/2023 11:45:55] Execution of command No.3.

If everything works, the only thing left is to run the script at Raspberry startup.

Other tutorials:

TUTORIAL No.1: Display the Raspberry temperature in Gladys.

TUTORIAL No.3: Indicate a user’s presence via their phone’s Wi‑Fi.

TUTORIAL No.4: Managing your robot vacuum running Valetudo in Gladys.

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