server_php_session_discover.php

<?php

header('Content-Type: text/plain');

$dir = new DirectoryIterator(ini_get('session.save_path'));

foreach ($dir as $file)
{
  if ($file->isDot())
  {
    continue;
  }

  // {$filename}\t{$last_modified_time}\n
  echo $file->getFilename()."\t".date('Y-m-d H:i:s', $file->getMTime()).PHP_EOL;
}