For example, I have something like this:
  if(ENV === 'production') {
    grunt.registerTask('default', ['mkdir', 'copy', 'min']); // production
  } else {
    grunt.registerTask('default', ['mkdir', 'copy']); // dev
  }
if I do ENV=development grunt or grunt, I want dev task to be executed, and if I do ENV=production grunt, i want production task to be executed.
I cannot register two tasks: default-dev, default-prod and run grunt default-dev or grunt default-prod.
I have to use ENV variable to specify which task to run.
 
    