diff --git a/src/Process.php b/src/Process.php
index 84fbc74..7fafb23 100644
--- a/src/Process.php
+++ b/src/Process.php
@@ -42,8 +42,12 @@ class Process {
         proc_terminate($this->process, $signal);
     }
 
+    public function status(): array { // get process status
+        return proc_get_status($this->process);
+    }
+
     public function isAlive(): bool { // whether sub process still running
-        return proc_get_status($this->process)['running'];
+        return $this->status()['running'];
     }
 
     public function quit(): int {
@@ -54,25 +58,25 @@ class Process {
 }
 
 
-$p = new Process(['sleep', '10'], $capture = true);
-echo "PID -> $p->pid\n";
-
-echo "Alive -> " . ($p->isAlive() ? 'yes' : 'no') . "\n";
-echo "Sleep 5s...\n";
-sleep(5);
-
-echo "Alive -> " . ($p->isAlive() ? 'yes' : 'no') . "\n";
-echo "Send kill signal\n";
-$p->signal(15);
-sleep(1);
-echo "Alive -> " . ($p->isAlive() ? 'yes' : 'no') . "\n";
-
-echo '--------------------------------------------' . PHP_EOL;
-echo $p->getStdout();
-echo '--------------------------------------------' . PHP_EOL;
-echo $p->getStdout();
-echo '--------------------------------------------' . PHP_EOL;
-echo $p->getStderr();
-echo '--------------------------------------------' . PHP_EOL;
-
-echo "Return code -> " . $p->quit() . "\n";
+//$p = new Process(['sleep', '10'], $capture = true);
+//echo "PID -> $p->pid\n";
+//
+//echo "Alive -> " . ($p->isAlive() ? 'yes' : 'no') . "\n";
+//echo "Sleep 5s...\n";
+//sleep(5);
+//
+//echo "Alive -> " . ($p->isAlive() ? 'yes' : 'no') . "\n";
+//echo "Send kill signal\n";
+//$p->signal(15);
+//sleep(1);
+//echo "Alive -> " . ($p->isAlive() ? 'yes' : 'no') . "\n";
+//
+//echo '--------------------------------------------' . PHP_EOL;
+//echo $p->getStdout();
+//echo '--------------------------------------------' . PHP_EOL;
+//echo $p->getStdout();
+//echo '--------------------------------------------' . PHP_EOL;
+//echo $p->getStderr();
+//echo '--------------------------------------------' . PHP_EOL;
+//
+//echo "Return code -> " . $p->quit() . "\n";
diff --git a/src/demo.php b/src/demo.php
index 1dc35b3..ffa565e 100644
--- a/src/demo.php
+++ b/src/demo.php
@@ -1,9 +1,55 @@
 <?php
 
-require_once 'Logger.php';
+//require_once 'Logger.php';
+//
+//logging::debug('debug');
+//logging::info('info');
+//logging::warning('warning');
+//logging::error('error');
+//logging::critical('critical');
 
-logging::debug('debug');
-logging::info('info');
-logging::warning('warning');
-logging::error('error');
-logging::critical('critical');
+require_once 'Process.php';
+
+//$vlmcsd = new Process(['/usr/bin/vlmcsd', '-De'], $capture = false);
+//var_dump($vlmcsd);
+//echo $vlmcsd->pid . PHP_EOL;
+//
+//while (true) {
+//    echo "Check vlmcsd...";
+//    if ($vlmcsd->isAlive()) {
+//        echo "Alive\n";
+//    } else {
+//        echo "Death\n";
+//        echo "try to restart\n";
+//    }
+//    sleep(1);
+//}
+
+$nginx = array(
+    'command' => ['/usr/sbin/nginx'],
+    'pidFile' => '/run/nginx/nginx.pid',
+);
+
+function getPid(string $pidFile): int { // get pid by given file
+    if (!file_exists($pidFile)) {
+        return -1; // file not exist
+    }
+    $file = fopen($pidFile, 'r');
+    if (!is_resource($file)) {
+        return -1; // file open failed
+    }
+    $content = fread($file, filesize($pidFile)); // read pid number
+    fclose($file);
+    return intval($content);
+}
+
+$p = new Process($nginx['command']);
+sleep(1);
+while (True) {
+    if (getPid($nginx['pidFile']) == -1) {
+        echo 'nginx exit' . PHP_EOL;
+        $p = new Process($nginx['command']);
+    }
+    $p->status();
+    sleep(1);
+}