ruby.rb

def checkFlagValue(flag,value)
	   # Remove the = symbol, which OptionParser leaves there if you use the shortflag (-p)
	  	value=value.gsub('=','')
	    if value.empty? 
	      usage("Missing value for --#{flag}")
	    end
	    return value
	end

	# If we have the correct number of arguments let's make sure we have the required options.
	Arguments = OptionParser.new do |opt|
		opt.on('--profile PROFILE',"The AWS profile to connect to.") do |o|
			profile=checkFlagValue('profile',o)
		end
		opt.on('--region [REGION]','The AWS region to use.') do |o|
			region=checkFlagValue('region',o)
		end
		opt.on('--retention-days [DAYS]','The number of days to hold the snapshots.') do |o|
			retention_days=checkFlagValue('retention_days',o)
		end
		opt.on('--[no-]dry-run','Test rather than actually running.') do |o|
			dry_run = true
		end
		opt.on('--instance instance','The instance id you want to snapshot') do |o|
			instance = o
		end
	end.parse!

	def usage(optional_message = nil)
		unless optional_message.nil?
	    	puts optional_message
	  	end
	  	puts Arguments.help
		exit 1
	end