This bundle allows you to merge pdf files with poppler util - pdfUnit
Open your command console, browse to your project and execute the following:
$ composer require melnikoved/poppler-bundle:dev-master
// app/AppKernel.php
public function registerBundles()
{
return array(
// ...
new Melnikoved\PopplerBundle\MelnikovedPopplerBundle(),
);
}
For merging pdf files you should use service 'poppler'
$this->get('poppler')->merge($inputFileNames, $outputFileName);