A really simple and quick script for Symfony2 console bash completions. These completions respond after you've typed symfony or app/console and press TAB.
Copy the file symfony2-completions.bash to somewhere on your disk and add to your .bashrc or .bash_profile:
source ~/path/to/symfony2-completsions.bash
And you should be good to go. For the first argument it will try to complete the command name, for the rest it will try to complete the command options. Note that your symfony or app/console utility needs to provide at least the list and help commands for this to work.