Check SSH multiplexing initialization

check.php

<?php
$host = 'beta'; // WRITE YOU HOSTNAME HERE

$run = function ($cmd, $write = '') {
    static $i = 0;
    $i++;
    $descriptors = array(
        array("pipe", "r"),
        array("pipe", "w"),
        array("pipe", "w")
    );
    echo "$i:$cmd\n";
    $process = proc_open($cmd, $descriptors, $pipes);

    if (is_resource($process)) {
        echo "$i:run '$write'\n";
        fwrite($pipes[0], $write);
        fclose($pipes[0]);

        echo "$i:" . stream_get_contents($pipes[1]);
        fclose($pipes[1]);

        $return_value = proc_close($process);
        echo "$i:command returned $return_value\n";
    } else {
        echo "$i:proc_open failure\n";
    }
};
$ssh = function ($args, $write) use ($run, $host) {
    $run("ssh $args $host 'bash -s'", $write);
};
$generateControlPath = function () use ($host) {
    $connectionData = "$host";
    $tryLongestPossible = 0;
    $controlPath = '';
    do {
        switch ($tryLongestPossible) {
            case 1:
                $controlPath = "~/.ssh/deployer_mux_$connectionData";
                break;
            case 2:
                $controlPath = "~/.ssh/deployer_mux_%C";
                break;
            case 3:
                $controlPath = "~/deployer_mux_$connectionData";
                break;
            case 4:
                $controlPath = "~/deployer_mux_%C";
                break;
            case 5:
                $controlPath = "~/mux_%C";
                break;
            case 6:
                throw new Exception("The multiplexing control path is too long. Control path is: $controlPath");
            default:
                $controlPath = "~/.ssh/deployer_mux_$connectionData";
        }
        $tryLongestPossible++;
    } while (strlen($controlPath) > 104); // Unix socket max length

    return $controlPath;
};

$controlPath = $generateControlPath();
$options = "-o ControlMaster=auto -o ControlPersist=60 -o ControlPath=$controlPath";

$ssh("$options", 'pwd');
$run("ssh -O check $options $host 2>&1");