UPDATE: This is changed now and author wants that we install drupal launcher and then drupal console per project as stated here so composer global require is no longer supported
To continue on installing globally vital drupal tools (http://drupaldump.com/install-composer-and-drush-globally)
You can install Drupal Console project globally using composer.
$ composer global require drupal/console:@stable
Add the binary directory to your class path:
$ echo "PATH=$PATH:~/.composer/vendor/bin" >> ~/.bash_profile
You can now execute console using:
$ drupal generate:module