Mailer Error

gistfile1.sh

$ rails g
Usage: rails generate GENERATOR [args] [options]

General options:
  -h, [--help]     # Print generator's options and usage
  -p, [--pretend]  # Run but do not make any changes
  -f, [--force]    # Overwrite files that already exist
  -s, [--skip]     # Skip files that already exist
  -q, [--quiet]    # Suppress status output

Please choose a generator below.

Rails:
  controller
  generator
  helper
  integration_test
  migration
  model
  observer
  performance_test
  plugin
  resource
  scaffold
  scaffold_controller
  session_migration
  stylesheets