The complete solution for Ruby command-line executables. Commander bridges the gap between other terminal related libraries you know and love (OptionParser, HighLine), while providing many new features, and an elegant API.

Code Quality Rank: L3
Monthly Downloads: 2,250,154
Programming language: Ruby
License: MIT License
Latest version: v4.6.0

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The complete solution for Ruby command-line executables. Commander bridges the gap between other terminal related libraries you know and love (OptionParser, HighLine), while providing many new features, and an elegant API.


  • Easier than baking cookies
  • Parses options using OptionParser
  • Auto-populates struct with options ( no more { |v| options[:recursive] = v } )
  • Auto-generates help documentation via pluggable help formatters
  • Optional default command when none is present
  • Global / Command level options
  • Packaged with two help formatters (Terminal, TerminalCompact)
  • Imports the highline gem for interacting with the terminal
  • Adds additional user interaction functionality
  • Highly customizable progress bar with intuitive, simple usage
  • Multi-word command name support such as drupal module install MOD, rather than drupal module_install MOD
  • Sexy paging for long bodies of text
  • Support for MacOS text-to-speech
  • Command aliasing (very powerful, as both switches and arguments can be used)
  • Growl notification support for MacOS
  • Use the commander executable to initialize a commander driven program


$ gem install commander

Quick Start

To generate a quick template for a commander app, run:

$ commander init yourfile.rb

To generate a quick modular style template for a commander app, run:

$ commander init --modular yourfile.rb


For more option examples view the Commander::Command#option method. Also an important feature to note is that action may be a class to instantiate, as well as an object, specifying a method to call, so view the RDoc for more information.

Classic style

require 'rubygems'
require 'commander/import'

# :name is optional, otherwise uses the basename of this executable
program :name, 'Foo Bar'
program :version, '1.0.0'
program :description, 'Stupid command that prints foo or bar.'

command :foo do |c|
  c.syntax = 'foobar foo'
  c.description = 'Displays foo'
  c.action do |args, options|
    say 'foo'

command :bar do |c|
  c.syntax = 'foobar bar [options]'
  c.description = 'Display bar with optional prefix and suffix'
  c.option '--prefix STRING', String, 'Adds a prefix to bar'
  c.option '--suffix STRING', String, 'Adds a suffix to bar'
  c.action do |args, options|
    options.default :prefix => '(', :suffix => ')'
    say "#{options.prefix}bar#{options.suffix}"

Example output:

$ foobar bar
# => (bar)

$ foobar bar --suffix '}' --prefix '{'
# => {bar}

Modular style

NOTE: Make sure to use require 'commander' rather than require 'commander/import', otherwise Commander methods will still be imported into the global namespace.

require 'rubygems'
require 'commander'

class MyApplication
  include Commander::Methods

  def run
    program :name, 'Foo Bar'
    program :version, '1.0.0'
    program :description, 'Stupid command that prints foo or bar.'

    command :foo do |c|
      c.syntax = 'foobar foo'
      c.description = 'Displays foo'
      c.action do |args, options|
        say 'foo'


MyApplication.new.run if $0 == __FILE__

Block style

require 'rubygems'
require 'commander'

Commander.configure do
  program :name, 'Foo Bar'
  program :version, '1.0.0'
  program :description, 'Stupid command that prints foo or bar.'

  # see classic style example for options


As mentioned above, the highline gem is imported into the global scope. Here are some quick examples for how to utilize highline in your commands:

# Ask for password masked with '*' character
ask("Password:  ") { |q| q.echo = "*" }

# Ask for password
ask("Password:  ") { |q| q.echo = false }

# Ask if the user agrees (yes or no)
agree("Do something?")

# Asks on a single line (note the space after ':')
ask("Name: ")

# Asks with new line after "Description:"

# Calls Date#parse to parse the date string passed
ask("Birthday? ", Date)

# Ensures Integer is within the range specified
ask("Age? ", Integer) { |q| q.in = 0..105 }

# Asks for a list of strings, converts to array
ask("Fav colors?", Array)

HighLine & Interaction Additions

In addition to highline's fantastic choice of methods, commander adds the following methods to simplify common tasks:

# Ask for password

# Ask for password with specific message and mask character
password "Enter your password please:", '-'

# Ask for CLASS, which may be any valid class responding to #parse. Date, Time, Array, etc
names = ask_for_array 'Names: '
bday = ask_for_date 'Birthday?: '

# Simple progress bar (Commander::UI::ProgressBar)
uris = %w[
progress uris do |uri|
  res = open uri
  # Do something with response

# 'Log' action to stdout
log "create", "path/to/file.rb"

# Enable paging of output after this point

# Ask editor for input (EDITOR environment variable or whichever is available: TextMate, vim, vi, emacs, nano, pico)

# Ask editor, supplying initial text
ask_editor 'previous data to update'

# Ask editor, preferring a specific editor
ask_editor 'previous data', 'vim'

# Choose from an array of elements
choice = choose("Favorite language?", :ruby, :perl, :js)

# Alter IO for the duration of the block
io new_input, new_output do
  new_input_contents = $stdin.read
  puts new_input_contents # outputs to new_output stream
# $stdin / $stdout reset back to original streams

# Speech synthesis
speak 'What is your favorite food? '
food = ask 'favorite food?: '
speak "Wow, I like #{food} too. We have so much in common."
speak "I like #{food} as well!", "Victoria", 190

# Execute arbitrary applescript
applescript 'foo'

# Converse with speech recognition server
case converse 'What is the best food?', :cookies => 'Cookies', :unknown => 'Nothing'
when :cookies
  speak 'o.m.g. you are awesome!'
  case converse 'That is lame, shall I convince you cookies are the best?', :yes => 'Ok', :no => 'No', :maybe => 'Maybe another time'
  when :yes
    speak 'Well you see, cookies are just fantastic, they melt in your mouth.'
    speak 'Ok then, bye.'

Growl Notifications

Commander provides methods for displaying Growl notifications. To use these methods you need to install https://github.com/tj/growl which utilizes the growlnotify executable. Note that growl is auto-imported by Commander when available, no need to require.

# Display a generic Growl notification
notify 'Something happened'

# Display an 'info' status notification
notify_info 'You have #{emails.length} new email(s)'

# Display an 'ok' status notification
notify_ok 'Gems updated'

# Display a 'warning' status notification
notify_warning '1 gem failed installation'

# Display an 'error' status notification
notify_error "Gem #{name} failed"

Commander Goodies

Option Defaults

The options struct passed to #action provides a #default method, allowing you to set defaults in a clean manner for options which have not been set.

command :foo do |c|
  c.option '--interval SECONDS', Integer, 'Interval in seconds'
  c.option '--timeout SECONDS', Integer, 'Timeout in seconds'
  c.action do |args, options|
    options.default \
      :interval => 2,
      :timeout  => 60

Command Aliasing

Aliases can be created using the #alias_command method like below:

command :'install gem' do |c|
  c.action { puts 'foo' }
alias_command :'gem install', :'install gem'

Or more complicated aliases can be made, passing any arguments as if it was invoked via the command line:

command :'install gem' do |c|
  c.syntax = 'install gem <name> [options]'
  c.option '--dest DIR', String, 'Destination directory'
  c.action { |args, options| puts "installing #{args.first} to #{options.dest}" }
alias_command :update, :'install gem', 'rubygems', '--dest', 'some_path'
$ foo update
# => installing rubygems to some_path

Command Defaults

Although working with a command executable framework provides many benefits over a single command implementation, sometimes you still want the ability to create a terse syntax for your command. With that in mind we may use #default_command to help with this. Considering our previous :'install gem' example:

default_command :update
$ foo
# => installing rubygems to some_path

Keeping in mind that commander searches for the longest possible match when considering a command, so if you were to pass arguments to foo like below, expecting them to be passed to :update, this would be incorrect, and would end up calling :'install gem', so be careful that the users do not need to use command names within the arguments.

$ foo install gem
# => installing  to

Long descriptions

If you need to have a long command description, keep your short description under summary, and consider multi-line strings for description:

  program :summary, 'Stupid command that prints foo or bar.'
  program :description, %q(

More information about that stupid command that prints foo or bar.

And more

Additional Global Help

Arbitrary help can be added using the following #program symbol:

program :help, 'Author', 'TJ Holowaychuk <[email protected]>'

Which will output the rest of the help doc, along with:


  TJ Holowaychuk <[email protected]>

Global Options

Although most switches will be at the command level, several are available by default at the global level, such as --version, and --help. Using #global_option you can add additional global options:

global_option('-c', '--config FILE', 'Load config data for your commands to use') { |file| ... }

This method accepts the same syntax as Commander::Command#option so check it out for documentation.

All global options regardless of providing a block are accessable at the command level. This means that instead of the following:

global_option('--verbose') { $verbose = true }
c.action do |args, options|
  say 'foo' if $verbose

You may:

global_option '--verbose'
c.action do |args, options|
  say 'foo' if options.verbose


Two core formatters are currently available, the default Terminal formatter as well as TerminalCompact. To utilize a different formatter simply use :help_formatter like below:

program :help_formatter, Commander::HelpFormatter::TerminalCompact

Or utilize the help formatter aliases:

program :help_formatter, :compact

This abstraction could be utilized to generate HTML documentation for your executable.


By default the -t and --trace global options are provided to allow users to get a backtrace to aid debugging.

You can disable these options:


Or make it always on:



When adding a global or command option, OptionParser implicitly adds a small switch even when not explicitly created, for example -c will be the same as --config in both examples, however -c will only appear in the documentation when explicitly assigning it.

global_option '-c', '--config FILE'
global_option '--config FILE'

ASCII Tables

For feature rich ASCII tables for your terminal app check out the terminal-table gem at https://github.com/tj/terminal-table

| Terminal | Table | Is | Wicked | Awesome               |
|          |       |    |        | get it while its hot! |

Running Specifications

$ rake spec


$ spec --color spec


Feel free to fork and request a pull, or submit a ticket https://github.com/commander-rb/commander/issues


This project is available under the MIT license. See LICENSE for details.

*Note that all licence references and agreements mentioned in the Commander README section above are relevant to that project's source code only.