3v4l.org

run code in 300+ PHP versions simultaneously
<?php echo syscall("echo foo"); function syscall($command){ $result = ""; if ($proc = popen("($command)2>&1","r")){ while (!feof($proc)) $result .= fgets($proc, 1000); pclose($proc); return $result; } } ?>

preferences:
41.89 ms | 402 KiB | 5 Q