composer dump-autoload not working on controller Laravel 5

I want run php /bin/composer.phar dump-autoload on my controller.
When I run shell_exec("php /bin/composer.phar dump-autoload");
dose not work because when run shell_exec("dir"); I am on public folder and When I run this command shell_exec("cd.. & php /bin/composer.phar dump-autoload"); Nothing not happen because when run cd .. ; dir I am on public folder yet. My host in centos 6

via Chebli Mohamed