```ruby
require 'tempfile'

module StackMaster
  module Commands
    class Lint
      include Command
      include Commander::UI

      def initialize(config, stack_definition, options = {})
        @config = config
        @stack_definition = stack_definition
      end

      def perform
        unless cfn_lint_available
          puts "Failed to run cfn-lint, do you have it installed and available in $PATH?"
          return
        end

        Tempfile.open(['stack', ".#{proposed_stack.template_format}"]) do |f|
          f.write(proposed_stack.template_body)
          system('cfn-lint', f.path).nil?
          puts "cfn-lint run complete"
        end
      end

      private

      def stack_definition
        @stack_definition ||= @config.find_stack(@region, @stack_name)
      end

      def proposed_stack
        @proposed_stack ||= Stack.generate(stack_definition, @config)
      end

      def cfn_lint_available
        !system('cfn-lint', '--version').nil?
      end
    end
  end
end
```

Make sure we flush the buffers
user
```ruby
require 'tempfile'

module StackMaster
  module Commands
    class Lint
      include Command
      include Commander::UI

      def initialize(config, stack_definition, options = {})
        @config = config
        @stack_definition = stack_definition
      end

      def perform
        unless cfn_lint_available
          puts "Failed to run cfn-lint, do you have it installed and available in $PATH?"
          return
        end

        Tempfile.open(['stack', ".#{proposed_stack.template_format}"]) do |f|
          f.write(proposed_stack.template_body)
          f.flush
          system('cfn-lint', f.path).nil?
          puts "cfn-lint run complete"
        end
      end

      private

      def stack_definition
        @stack_definition ||= @config.find_stack(@region, @stack_name)
      end

      def proposed_stack
        @proposed_stack ||= Stack.generate(stack_definition, @config)
      end

      def cfn_lint_available
        !system('cfn-lint', '--version').nil?
      end
    end
  end
end
```
assistant