cmdparse

cmdparse

… is an advanced Ruby command line parser supporting nested commands.

It allows the creation of “command style” programs, like git or svn, that perform different functions depending on which command is invoked. Additionally, nesting of commands, i.e. commands that take commands themselves, is also possible. For option parsing, the battle-tested Ruby standard library optparse is used.

A typical command line for a program which uses commands looks like this:

$ net --verbose ipaddr add 192.168.0.1 193.150.0.1

Features

  • Commands can have sub-commands
  • Built-in commands for showing help and the version of the program
  • Automatic discovery of names and number of required/optional command arguments
  • Truly global options that can be used on any command
  • No need to learn a special DSL
  • Use POROs (plain old Ruby objects) for creating commands or create them on the fly
  • All OptionParser goodies available for option parsing
  • Easy to use

Quickstart

Here are two short code samples which show how to use cmdparse. A complete example application can be found in the tutorial, also see the API documentation of CmdParse::CommandParser and CmdParse::Command.

A sample CLI program where commands are defined using classes:

require 'cmdparse'

class TestCmd < CmdParse::Command
  def initialize
    super('test')
    short_desc('Short description of command')
    add_command(TestSubCmd.new)
  end
end

class TestSubCmd < CmdParse::Command
  def initialize
    super('sub', takes_commands: false)
    options.on('-x', '--example', 'Example option') { puts 'example' }
  end

  def execute(name, *opt)
    puts "Hello #{name}, options: #{opt.join(', ')}"
  end
end

parser = CmdParse::CommandParser.new(handle_exceptions: :no_help)
parser.add_command(CmdParse::HelpCommand.new)
parser.add_command(TestCmd.new)
parser.parse

The same program but with the commands defined on the fly:

require 'cmdparse'

parser = CmdParse::CommandParser.new(handle_exceptions: :no_help)
parser.add_command(CmdParse::HelpCommand.new)
parser.add_command('test') do |test_cmd|
  test_cmd.short_desc('Short description of command')

  test_cmd.add_command('sub') do |sub_cmd|
    sub_cmd.takes_commands(false)
    sub_cmd.options.on('-x', '--example', 'Example option') { puts 'example' }
    sub_cmd.action do |name, *opt|
      puts "Hello #{name}, options: #{opt.join(', ')}"
    end
  end
end
parser.parse

Sample output for different invocations:

$ sample.rb 
Error while parsing command line:
    No command given

$ sample.rb help
Usage: sample {help | test}

Available commands:
    help              Provide help for individual commands
    test              Short description of command
      sub            

Global Options:
    -h, --help                       Show help


$ sample.rb test sub
Error while parsing command line:
    Not enough arguments provided, minimum is: 1

$ sample.rb test sub -h
Usage: sample test sub [options] [NAME] [OPT...]

Options (take precedence over global options):
    -x, --example                    Example option

Global Options:
    -h, --help                       Show help


$ sample.rb test sub Thomas
Hello Thomas, options: 

$ sample.rb test sub -x Thomas opt1 opt2
example
Hello Thomas, options: opt1, opt2

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