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Documentation quickstart: See Trollop.options and then Trollop::Parser#opt. Also see the examples at


Trollop is a commandline option parser for Ruby that just gets out of your way. One line of code per option is all you need to write. For that, you get a nice automatically-generated help page, robust option parsing, and sensible defaults for everything you don't specify.


  • Dirt-simple usage.
  • Single file. Throw it in lib/ if you don't want to make it a Rubygem dependency.
  • Sensible defaults. No tweaking necessary, much tweaking possible.
  • Support for long options, short options, subcommands, and automatic type validation and conversion.
  • Automatic help message generation, wrapped to current screen width.


  • A burning desire to write less code.


  • gem install trollop


require 'trollop'
opts = Trollop::options do
  opt :monkey, "Use monkey mode"                    # flag --monkey, default false
  opt :name, "Monkey name", :type => :string        # string --name <s>, default nil
  opt :num_limbs, "Number of limbs", :default => 4  # integer --num-limbs <i>, default to 4

p opts # a hash: { :monkey=>false, :name=>nil, :num_limbs=>4, :help=>false }


Copyright © 2008-2014 William Morgan.

Copyright © 2014 Red Hat, Inc.

Trollop is released under the [MIT License][].