Symfony command line on Ubuntu without using PHP

Question

Why if we type a Symfony command line on Ubuntu without using PHP, we don't have an error ?

For example

php app/console cache:clear

is the same thing than :

app/console cache:clear

Answer 1

We don't have an error.

app/console cache:clear
[OK] Cache for the "dev" environment (debug=true) was successfully cleared. 

Because php env defined in app/console

#!/usr/bin/env php

Also, app/console should have permissions for execute