解决方法
我知道了.命令是
rails generate
输出是这样的：
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: assets controller generator helper inherited_resources_controller integration_test mailer migration model observer performance_test resource responders_controller scaffold scaffold_controller session_migration task ActiveRecord: active_record:devise active_record:migration active_record:model active_record:observer active_record:session_migration Coffee: coffee:assets Devise: devise devise:install devise:views