Spawn a shell command from PHP, check Process status, respawn if not running.

php-spawn-command-check-processp-status.php

<?php
 
/**
 * $ php p.php
 *   S SPAWNED! RRRRS SPAWNED! RRRRRS SPAWNED! R
 */
 
function spawn() {
 
    $descriptorspec = array(
        0 => array("pipe", "r"),  // stdin
        1 => array("pipe", "w"),  // stdout
        2 => array("pipe", "w")   // stderr ?? instead of a file
      );
 
    $process = proc_open('bash -c "sleep 5s"', $descriptorspec, $pipes);
 
    echo " SPAWNED! ";
 
    return $process;
}
 
function isRunning($process) {
 
    if (!is_resource($process)) {
        return false;
    }
 
    $status = proc_get_status($process);
    return ($status["running"]);
}
 
$process = null;
 
while (true) {
 
    sleep(1);
    if (isRunning($process)) {
        echo "R";
    } else {
        echo "S";
        $process = spawn();
    }
}