gistfile1.txt

require 'optparse'

options = {}
optparse = OptionParser.new do|opts|
	opts.banner = "Usage: ruby #{File.basename(__FILE__)} -t <target ip address> -i <input file name> [-o <output file name>]"
	opts.on( '-t', '--target HOST', 'Target\'s IP address' ) do|h|
		options[:host] = h
	end
	opts.on('-i', '--input FILE', 'Input file name') do |f|
		options[:input] = f
	end
	opts.on('-o', '--output FILE', 'Input file name') do |f|
		options[:output] = f
	end
end

begin                                                                                                                                                                                                             
  optparse.parse!                                                                                                                                                                                                 
  mandatory = [:host, :input]                                                                                                                          
  missing = mandatory.select{ |param| options[param].nil? }                                                                                         
  if not missing.empty?                                                                                                               
    puts "Missing options: #{missing.join(', ')}"                                                                                                          
    puts optparse                                                                                                         
    exit                                                                                                                   
  end                                                                                                                                                                                 
rescue OptionParser::InvalidOption, OptionParser::MissingArgument                                                                                                                                                
  puts $!.to_s
  puts optparse 
  exit 
end