www/api/mqtt.php

<?php
declare(strict_types=1);

function mqtt_publish(string $topic, string $msg): void {
    $cmd = sprintf(
        'mosquitto_pub -h 127.0.0.1 -p 1883 -t %s -m %s',
        escapeshellarg($topic),
        escapeshellarg($msg)
    );
    shell_exec($cmd . " > /dev/null 2>&1");
}