There are only three ways to invoke install.sh

./install.sh
./install.sh --force
./install.sh -f

I can write it easily. However I am trying to make use of OptionParse. This is what I have so far.

 def self.parse
    option = {}
    optparse = OptionParser.new do |opts|
      opts.banner = "Usage: ./install.sh [--force]"
      opts.on('-f', '--force', '') do |dir|
        option[:force] = true
      end
    end

    begin
      optparse.parse!
    rescue OptionParser::InvalidOption => e
      puts e
    end
  end

How do I provide feedback to user in case user provides something other than -f or --force.