FileObject.php

<?php

class FileObject extends SplFileObject {

    public function tail($amount)
    {
        $lastKey = $this->key();

        $this->seek(PHP_INT_MAX);

        $end = $this->key();

        $start = $end - $amount;

        // Set as last Line of iterations 

        $this->seek($lastKey);

        return new LimitIterator($this, $start, $end);
    }
}