Use bin/console instead of app/console.
However, Symfony 3.0 was just released yesterday. http://symfony.com/blog/symfony-3-0-0-released. Most of the core concepts between S2 and S3 are the same but the implementations have changed significantly. For example, the form components work differently. Most of the current documentation is S2 specific and will not work under S3. Furthermore, many 3rd party bundles such as FOSUserBundle will not currently work under S3.
So, if want to use bleeding edge software then roll up your sleeves and start reading the upgrade files as well as the blog.
If you just want to make applications then start over with S2.8.
Something else that will be really fun. The 'current' documents now point to S3. So most of the S2 links will now point to incorrect information.
php app/consoleUse in Symfony3:php bin/console- Imanali Mamadiev