update

1 files changed, 1355 insertions, 1923 deletions

diff --git a/node_modules/commander/index.js b/node_modules/commander/index.js
index 985a8cfc..37d20cc5 100644
--- a/node_modules/commander/index.js
+++ b/node_modules/commander/index.js
@@ -2,499 +2,91 @@
  * Module dependencies.
  */
 
-const EventEmitter = require('events').EventEmitter;
-const childProcess = require('child_process');
-const path = require('path');
-const fs = require('fs');
-
-// @ts-check
-
-// Although this is a class, methods are static in style to allow override using subclass or just functions.
-class Help {
-  constructor() {
-    this.helpWidth = undefined;
-    this.sortSubcommands = false;
-    this.sortOptions = false;
-  }
-
-  /**
-   * Get an array of the visible subcommands. Includes a placeholder for the implicit help command, if there is one.
-   *
-   * @param {Command} cmd
-   * @returns {Command[]}
-   */
-
-  visibleCommands(cmd) {
-    const visibleCommands = cmd.commands.filter(cmd => !cmd._hidden);
-    if (cmd._hasImplicitHelpCommand()) {
-      // Create a command matching the implicit help command.
-      const args = cmd._helpCommandnameAndArgs.split(/ +/);
-      const helpCommand = cmd.createCommand(args.shift())
-        .helpOption(false);
-      helpCommand.description(cmd._helpCommandDescription);
-      helpCommand._parseExpectedArgs(args);
-      visibleCommands.push(helpCommand);
-    }
-    if (this.sortSubcommands) {
-      visibleCommands.sort((a, b) => {
-        return a.name().localeCompare(b.name());
-      });
-    }
-    return visibleCommands;
-  }
-
-  /**
-   * Get an array of the visible options. Includes a placeholder for the implicit help option, if there is one.
-   *
-   * @param {Command} cmd
-   * @returns {Option[]}
-   */
-
-  visibleOptions(cmd) {
-    const visibleOptions = cmd.options.filter((option) => !option.hidden);
-    // Implicit help
-    const showShortHelpFlag = cmd._hasHelpOption && cmd._helpShortFlag && !cmd._findOption(cmd._helpShortFlag);
-    const showLongHelpFlag = cmd._hasHelpOption && !cmd._findOption(cmd._helpLongFlag);
-    if (showShortHelpFlag || showLongHelpFlag) {
-      let helpOption;
-      if (!showShortHelpFlag) {
-        helpOption = cmd.createOption(cmd._helpLongFlag, cmd._helpDescription);
-      } else if (!showLongHelpFlag) {
-        helpOption = cmd.createOption(cmd._helpShortFlag, cmd._helpDescription);
-      } else {
-        helpOption = cmd.createOption(cmd._helpFlags, cmd._helpDescription);
-      }
-      visibleOptions.push(helpOption);
-    }
-    if (this.sortOptions) {
-      const getSortKey = (option) => {
-        // WYSIWYG for order displayed in help with short before long, no special handling for negated.
-        return option.short ? option.short.replace(/^-/, '') : option.long.replace(/^--/, '');
-      };
-      visibleOptions.sort((a, b) => {
-        return getSortKey(a).localeCompare(getSortKey(b));
-      });
-    }
-    return visibleOptions;
-  }
-
-  /**
-   * Get an array of the arguments which have descriptions.
-   *
-   * @param {Command} cmd
-   * @returns {{ term: string, description:string }[]}
-   */
-
-  visibleArguments(cmd) {
-    if (cmd._argsDescription && cmd._args.length) {
-      return cmd._args.map((argument) => {
-        return { term: argument.name, description: cmd._argsDescription[argument.name] || '' };
-      }, 0);
-    }
-    return [];
-  }
+var EventEmitter = require('events').EventEmitter;
+var spawn = require('child_process').spawn;
+var path = require('path');
+var dirname = path.dirname;
+var basename = path.basename;
+var fs = require('fs');
 
-  /**
-   * Get the command term to show in the list of subcommands.
-   *
-   * @param {Command} cmd
-   * @returns {string}
-   */
-
-  subcommandTerm(cmd) {
-    // Legacy. Ignores custom usage string, and nested commands.
-    const args = cmd._args.map(arg => humanReadableArgName(arg)).join(' ');
-    return cmd._name +
-      (cmd._aliases[0] ? '|' + cmd._aliases[0] : '') +
-      (cmd.options.length ? ' [options]' : '') + // simplistic check for non-help option
-      (args ? ' ' + args : '');
-  }
-
-  /**
-   * Get the option term to show in the list of options.
-   *
-   * @param {Option} option
-   * @returns {string}
-   */
-
-  optionTerm(option) {
-    return option.flags;
-  }
-
-  /**
-   * Get the longest command term length.
-   *
-   * @param {Command} cmd
-   * @param {Help} helper
-   * @returns {number}
-   */
-
-  longestSubcommandTermLength(cmd, helper) {
-    return helper.visibleCommands(cmd).reduce((max, command) => {
-      return Math.max(max, helper.subcommandTerm(command).length);
-    }, 0);
-  };
-
-  /**
-   * Get the longest option term length.
-   *
-   * @param {Command} cmd
-   * @param {Help} helper
-   * @returns {number}
-   */
-
-  longestOptionTermLength(cmd, helper) {
-    return helper.visibleOptions(cmd).reduce((max, option) => {
-      return Math.max(max, helper.optionTerm(option).length);
-    }, 0);
-  };
-
-  /**
-   * Get the longest argument term length.
-   *
-   * @param {Command} cmd
-   * @param {Help} helper
-   * @returns {number}
-   */
-
-  longestArgumentTermLength(cmd, helper) {
-    return helper.visibleArguments(cmd).reduce((max, argument) => {
-      return Math.max(max, argument.term.length);
-    }, 0);
-  };
-
-  /**
-   * Get the command usage to be displayed at the top of the built-in help.
-   *
-   * @param {Command} cmd
-   * @returns {string}
-   */
-
-  commandUsage(cmd) {
-    // Usage
-    let cmdName = cmd._name;
-    if (cmd._aliases[0]) {
-      cmdName = cmdName + '|' + cmd._aliases[0];
-    }
-    let parentCmdNames = '';
-    for (let parentCmd = cmd.parent; parentCmd; parentCmd = parentCmd.parent) {
-      parentCmdNames = parentCmd.name() + ' ' + parentCmdNames;
-    }
-    return parentCmdNames + cmdName + ' ' + cmd.usage();
-  }
-
-  /**
-   * Get the description for the command.
-   *
-   * @param {Command} cmd
-   * @returns {string}
-   */
-
-  commandDescription(cmd) {
-    // @ts-ignore: overloaded return type
-    return cmd.description();
-  }
-
-  /**
-   * Get the command description to show in the list of subcommands.
-   *
-   * @param {Command} cmd
-   * @returns {string}
-   */
-
-  subcommandDescription(cmd) {
-    // @ts-ignore: overloaded return type
-    return cmd.description();
-  }
-
-  /**
-   * Get the option description to show in the list of options.
-   *
-   * @param {Option} option
-   * @return {string}
-   */
-
-  optionDescription(option) {
-    if (option.negate) {
-      return option.description;
-    }
-    const extraInfo = [];
-    if (option.argChoices) {
-      extraInfo.push(
-        // use stringify to match the display of the default value
-        `choices: ${option.argChoices.map((choice) => JSON.stringify(choice)).join(', ')}`);
-    }
-    if (option.defaultValue !== undefined) {
-      extraInfo.push(`default: ${option.defaultValueDescription || JSON.stringify(option.defaultValue)}`);
-    }
-    if (extraInfo.length > 0) {
-      return `${option.description} (${extraInfo.join(', ')})`;
-    }
-    return option.description;
-  };
-
-  /**
-   * Generate the built-in help text.
-   *
-   * @param {Command} cmd
-   * @param {Help} helper
-   * @returns {string}
-   */
-
-  formatHelp(cmd, helper) {
-    const termWidth = helper.padWidth(cmd, helper);
-    const helpWidth = helper.helpWidth || 80;
-    const itemIndentWidth = 2;
-    const itemSeparatorWidth = 2; // between term and description
-    function formatItem(term, description) {
-      if (description) {
-        const fullText = `${term.padEnd(termWidth + itemSeparatorWidth)}${description}`;
-        return helper.wrap(fullText, helpWidth - itemIndentWidth, termWidth + itemSeparatorWidth);
-      }
-      return term;
-    };
-    function formatList(textArray) {
-      return textArray.join('\n').replace(/^/gm, ' '.repeat(itemIndentWidth));
-    }
-
-    // Usage
-    let output = [`Usage: ${helper.commandUsage(cmd)}`, ''];
+/**
+ * Inherit `Command` from `EventEmitter.prototype`.
+ */
 
-    // Description
-    const commandDescription = helper.commandDescription(cmd);
-    if (commandDescription.length > 0) {
-      output = output.concat([commandDescription, '']);
-    }
+require('util').inherits(Command, EventEmitter);
 
-    // Arguments
-    const argumentList = helper.visibleArguments(cmd).map((argument) => {
-      return formatItem(argument.term, argument.description);
-    });
-    if (argumentList.length > 0) {
-      output = output.concat(['Arguments:', formatList(argumentList), '']);
-    }
+/**
+ * Expose the root command.
+ */
 
-    // Options
-    const optionList = helper.visibleOptions(cmd).map((option) => {
-      return formatItem(helper.optionTerm(option), helper.optionDescription(option));
-    });
-    if (optionList.length > 0) {
-      output = output.concat(['Options:', formatList(optionList), '']);
-    }
+exports = module.exports = new Command();
 
-    // Commands
-    const commandList = helper.visibleCommands(cmd).map((cmd) => {
-      return formatItem(helper.subcommandTerm(cmd), helper.subcommandDescription(cmd));
-    });
-    if (commandList.length > 0) {
-      output = output.concat(['Commands:', formatList(commandList), '']);
-    }
+/**
+ * Expose `Command`.
+ */
 
-    return output.join('\n');
-  }
+exports.Command = Command;
 
-  /**
-   * Calculate the pad width from the maximum term length.
-   *
-   * @param {Command} cmd
-   * @param {Help} helper
-   * @returns {number}
-   */
+/**
+ * Expose `Option`.
+ */
 
-  padWidth(cmd, helper) {
-    return Math.max(
-      helper.longestOptionTermLength(cmd, helper),
-      helper.longestSubcommandTermLength(cmd, helper),
-      helper.longestArgumentTermLength(cmd, helper)
-    );
-  };
+exports.Option = Option;
 
-  /**
-   * Wrap the given string to width characters per line, with lines after the first indented.
-   * Do not wrap if insufficient room for wrapping (minColumnWidth), or string is manually formatted.
-   *
-   * @param {string} str
-   * @param {number} width
-   * @param {number} indent
-   * @param {number} [minColumnWidth=40]
-   * @return {string}
-   *
-   */
+/**
+ * Initialize a new `Option` with the given `flags` and `description`.
+ *
+ * @param {String} flags
+ * @param {String} description
+ * @api public
+ */
 
-  wrap(str, width, indent, minColumnWidth = 40) {
-    // Detect manually wrapped and indented strings by searching for line breaks
-    // followed by multiple spaces/tabs.
-    if (str.match(/[\n]\s+/)) return str;
-    // Do not wrap if not enough room for a wrapped column of text (as could end up with a word per line).
-    const columnWidth = width - indent;
-    if (columnWidth < minColumnWidth) return str;
-
-    const leadingStr = str.substr(0, indent);
-    const columnText = str.substr(indent);
-
-    const indentString = ' '.repeat(indent);
-    const regex = new RegExp('.{1,' + (columnWidth - 1) + '}([\\s\u200B]|$)|[^\\s\u200B]+?([\\s\u200B]|$)', 'g');
-    const lines = columnText.match(regex) || [];
-    return leadingStr + lines.map((line, i) => {
-      if (line.slice(-1) === '\n') {
-        line = line.slice(0, line.length - 1);
-      }
-      return ((i > 0) ? indentString : '') + line.trimRight();
-    }).join('\n');
-  }
+function Option(flags, description) {
+  this.flags = flags;
+  this.required = flags.indexOf('<') >= 0; // A value must be supplied when the option is specified.
+  this.optional = flags.indexOf('[') >= 0; // A value is optional when the option is specified.
+  this.mandatory = false; // The option must have a value after parsing, which usually means it must be specified on command line.
+  this.negate = flags.indexOf('-no-') !== -1;
+  flags = flags.split(/[ ,|]+/);
+  if (flags.length > 1 && !/^[[<]/.test(flags[1])) this.short = flags.shift();
+  this.long = flags.shift();
+  this.description = description || '';
 }
 
-class Option {
-  /**
-   * Initialize a new `Option` with the given `flags` and `description`.
-   *
-   * @param {string} flags
-   * @param {string} [description]
-   */
-
-  constructor(flags, description) {
-    this.flags = flags;
-    this.description = description || '';
-
-    this.required = flags.includes('<'); // A value must be supplied when the option is specified.
-    this.optional = flags.includes('['); // A value is optional when the option is specified.
-    // variadic test ignores <value,...> et al which might be used to describe custom splitting of single argument
-    this.variadic = /\w\.\.\.[>\]]$/.test(flags); // The option can take multiple values.
-    this.mandatory = false; // The option must have a value after parsing, which usually means it must be specified on command line.
-    const optionFlags = _parseOptionFlags(flags);
-    this.short = optionFlags.shortFlag;
-    this.long = optionFlags.longFlag;
-    this.negate = false;
-    if (this.long) {
-      this.negate = this.long.startsWith('--no-');
-    }
-    this.defaultValue = undefined;
-    this.defaultValueDescription = undefined;
-    this.parseArg = undefined;
-    this.hidden = false;
-    this.argChoices = undefined;
-  }
-
-  /**
-   * Set the default value, and optionally supply the description to be displayed in the help.
-   *
-   * @param {any} value
-   * @param {string} [description]
-   * @return {Option}
-   */
-
-  default(value, description) {
-    this.defaultValue = value;
-    this.defaultValueDescription = description;
-    return this;
-  };
-
-  /**
-   * Set the custom handler for processing CLI option arguments into option values.
-   *
-   * @param {Function} [fn]
-   * @return {Option}
-   */
-
-  argParser(fn) {
-    this.parseArg = fn;
-    return this;
-  };
-
-  /**
-   * Whether the option is mandatory and must have a value after parsing.
-   *
-   * @param {boolean} [mandatory=true]
-   * @return {Option}
-   */
-
-  makeOptionMandatory(mandatory = true) {
-    this.mandatory = !!mandatory;
-    return this;
-  };
-
-  /**
-   * Hide option in help.
-   *
-   * @param {boolean} [hide=true]
-   * @return {Option}
-   */
-
-  hideHelp(hide = true) {
-    this.hidden = !!hide;
-    return this;
-  };
-
-  /**
-   * @api private
-   */
-
-  _concatValue(value, previous) {
-    if (previous === this.defaultValue || !Array.isArray(previous)) {
-      return [value];
-    }
-
-    return previous.concat(value);
-  }
-
-  /**
-   * Only allow option value to be one of choices.
-   *
-   * @param {string[]} values
-   * @return {Option}
-   */
-
-  choices(values) {
-    this.argChoices = values;
-    this.parseArg = (arg, previous) => {
-      if (!values.includes(arg)) {
-        throw new InvalidOptionArgumentError(`Allowed choices are ${values.join(', ')}.`);
-      }
-      if (this.variadic) {
-        return this._concatValue(arg, previous);
-      }
-      return arg;
-    };
-    return this;
-  };
-
-  /**
-   * Return option name.
-   *
-   * @return {string}
-   */
+/**
+ * Return option name.
+ *
+ * @return {String}
+ * @api private
+ */
 
-  name() {
-    if (this.long) {
-      return this.long.replace(/^--/, '');
-    }
-    return this.short.replace(/^-/, '');
-  };
+Option.prototype.name = function() {
+  return this.long.replace(/^--/, '');
+};
 
-  /**
-   * Return option name, in a camelcase format that can be used
-   * as a object attribute key.
-   *
-   * @return {string}
-   * @api private
-   */
+/**
+ * Return option name, in a camelcase format that can be used
+ * as a object attribute key.
+ *
+ * @return {String}
+ * @api private
+ */
 
-  attributeName() {
-    return camelcase(this.name().replace(/^no-/, ''));
-  };
+Option.prototype.attributeName = function() {
+  return camelcase(this.name().replace(/^no-/, ''));
+};
 
-  /**
-   * Check if `arg` matches the short or long flag.
-   *
-   * @param {string} arg
-   * @return {boolean}
-   * @api private
-   */
+/**
+ * Check if `arg` matches the short or long flag.
+ *
+ * @param {String} arg
+ * @return {Boolean}
+ * @api private
+ */
 
-  is(arg) {
-    return this.short === arg || this.long === arg;
-  };
-}
+Option.prototype.is = function(arg) {
+  return this.short === arg || this.long === arg;
+};
 
 /**
  * CommanderError class
@@ -503,9 +95,9 @@ class Option {
 class CommanderError extends Error {
   /**
    * Constructs the CommanderError class
-   * @param {number} exitCode suggested exit code which could be used with process.exit
-   * @param {string} code an id string representing the error
-   * @param {string} message human-readable description of the error
+   * @param {Number} exitCode suggested exit code which could be used with process.exit
+   * @param {String} code an id string representing the error
+   * @param {String} message human-readable description of the error
    * @constructor
    */
   constructor(exitCode, code, message) {
@@ -515,1619 +107,1470 @@ class CommanderError extends Error {
     this.name = this.constructor.name;
     this.code = code;
     this.exitCode = exitCode;
-    this.nestedError = undefined;
   }
 }
 
+exports.CommanderError = CommanderError;
+
 /**
- * InvalidOptionArgumentError class
- * @class
+ * Initialize a new `Command`.
+ *
+ * @param {String} [name]
+ * @api public
  */
-class InvalidOptionArgumentError extends CommanderError {
-  /**
-   * Constructs the InvalidOptionArgumentError class
-   * @param {string} [message] explanation of why argument is invalid
-   * @constructor
-   */
-  constructor(message) {
-    super(1, 'commander.invalidOptionArgument', message);
-    // properly capture stack trace in Node.js
-    Error.captureStackTrace(this, this.constructor);
-    this.name = this.constructor.name;
-  }
-}
 
-class Command extends EventEmitter {
-  /**
-   * Initialize a new `Command`.
-   *
-   * @param {string} [name]
-   */
+function Command(name) {
+  this.commands = [];
+  this.options = [];
+  this._execs = new Set();
+  this._allowUnknownOption = false;
+  this._args = [];
+  this._name = name || '';
+  this._optionValues = {};
+  this._storeOptionsAsProperties = true; // backwards compatible by default
+  this._passCommandToAction = true; // backwards compatible by default
+  this._actionResults = [];
+
+  this._helpFlags = '-h, --help';
+  this._helpDescription = 'output usage information';
+  this._helpShortFlag = '-h';
+  this._helpLongFlag = '--help';
+}
 
-  constructor(name) {
-    super();
-    this.commands = [];
-    this.options = [];
-    this.parent = null;
-    this._allowUnknownOption = false;
-    this._allowExcessArguments = true;
-    this._args = [];
-    this.rawArgs = null;
-    this._scriptPath = null;
-    this._name = name || '';
-    this._optionValues = {};
-    this._storeOptionsAsProperties = false;
-    this._actionResults = [];
-    this._actionHandler = null;
-    this._executableHandler = false;
-    this._executableFile = null; // custom name for executable
-    this._defaultCommandName = null;
-    this._exitCallback = null;
-    this._aliases = [];
-    this._combineFlagAndOptionalValue = true;
-    this._description = '';
-    this._argsDescription = undefined;
-    this._enablePositionalOptions = false;
-    this._passThroughOptions = false;
-
-    // see .configureOutput() for docs
-    this._outputConfiguration = {
-      writeOut: (str) => process.stdout.write(str),
-      writeErr: (str) => process.stderr.write(str),
-      getOutHelpWidth: () => process.stdout.isTTY ? process.stdout.columns : undefined,
-      getErrHelpWidth: () => process.stderr.isTTY ? process.stderr.columns : undefined,
-      outputError: (str, write) => write(str)
-    };
+/**
+ * Define a command.
+ *
+ * There are two styles of command: pay attention to where to put the description.
+ *
+ * Examples:
+ *
+ *      // Command implemented using action handler (description is supplied separately to `.command`)
+ *      program
+ *        .command('clone <source> [destination]')
+ *        .description('clone a repository into a newly created directory')
+ *        .action((source, destination) => {
+ *          console.log('clone command called');
+ *        });
+ *
+ *      // Command implemented using separate executable file (description is second parameter to `.command`)
+ *      program
+ *        .command('start <service>', 'start named service')
+ *        .command('stop [service]', 'stop named service, or all if no name supplied');
+ *
+ * @param {string} nameAndArgs - command name and arguments, args are `<required>` or `[optional]` and last may also be `variadic...`
+ * @param {Object|string} [actionOptsOrExecDesc] - configuration options (for action), or description (for executable)
+ * @param {Object} [execOpts] - configuration options (for executable)
+ * @return {Command} returns new command for action handler, or top-level command for executable command
+ * @api public
+ */
 
-    this._hidden = false;
-    this._hasHelpOption = true;
-    this._helpFlags = '-h, --help';
-    this._helpDescription = 'display help for command';
-    this._helpShortFlag = '-h';
-    this._helpLongFlag = '--help';
-    this._addImplicitHelpCommand = undefined; // Deliberately undefined, not decided whether true or false
-    this._helpCommandName = 'help';
-    this._helpCommandnameAndArgs = 'help [command]';
-    this._helpCommandDescription = 'display help for command';
-    this._helpConfiguration = {};
+Command.prototype.command = function(nameAndArgs, actionOptsOrExecDesc, execOpts) {
+  var desc = actionOptsOrExecDesc;
+  var opts = execOpts;
+  if (typeof desc === 'object' && desc !== null) {
+    opts = desc;
+    desc = null;
+  }
+  opts = opts || {};
+  var args = nameAndArgs.split(/ +/);
+  var cmd = new Command(args.shift());
+
+  if (desc) {
+    cmd.description(desc);
+    this.executables = true;
+    this._execs.add(cmd._name);
+    if (opts.isDefault) this.defaultExecutable = cmd._name;
   }
+  cmd._noHelp = !!opts.noHelp;
+  cmd._helpFlags = this._helpFlags;
+  cmd._helpDescription = this._helpDescription;
+  cmd._helpShortFlag = this._helpShortFlag;
+  cmd._helpLongFlag = this._helpLongFlag;
+  cmd._exitCallback = this._exitCallback;
+  cmd._storeOptionsAsProperties = this._storeOptionsAsProperties;
+  cmd._passCommandToAction = this._passCommandToAction;
+
+  cmd._executableFile = opts.executableFile; // Custom name for executable file
+  this.commands.push(cmd);
+  cmd.parseExpectedArgs(args);
+  cmd.parent = this;
+
+  if (desc) return this;
+  return cmd;
+};
 
-  /**
-   * Define a command.
-   *
-   * There are two styles of command: pay attention to where to put the description.
-   *
-   * Examples:
-   *
-   *      // Command implemented using action handler (description is supplied separately to `.command`)
-   *      program
-   *        .command('clone <source> [destination]')
-   *        .description('clone a repository into a newly created directory')
-   *        .action((source, destination) => {
-   *          console.log('clone command called');
-   *        });
-   *
-   *      // Command implemented using separate executable file (description is second parameter to `.command`)
-   *      program
-   *        .command('start <service>', 'start named service')
-   *        .command('stop [service]', 'stop named service, or all if no name supplied');
-   *
-   * @param {string} nameAndArgs - command name and arguments, args are `<required>` or `[optional]` and last may also be `variadic...`
-   * @param {Object|string} [actionOptsOrExecDesc] - configuration options (for action), or description (for executable)
-   * @param {Object} [execOpts] - configuration options (for executable)
-   * @return {Command} returns new command for action handler, or `this` for executable command
-   */
+/**
+ * Define argument syntax for the top-level command.
+ *
+ * @api public
+ */
 
-  command(nameAndArgs, actionOptsOrExecDesc, execOpts) {
-    let desc = actionOptsOrExecDesc;
-    let opts = execOpts;
-    if (typeof desc === 'object' && desc !== null) {
-      opts = desc;
-      desc = null;
-    }
-    opts = opts || {};
-    const args = nameAndArgs.split(/ +/);
-    const cmd = this.createCommand(args.shift());
+Command.prototype.arguments = function(desc) {
+  return this.parseExpectedArgs(desc.split(/ +/));
+};
 
-    if (desc) {
-      cmd.description(desc);
-      cmd._executableHandler = true;
-    }
-    if (opts.isDefault) this._defaultCommandName = cmd._name;
-
-    cmd._outputConfiguration = this._outputConfiguration;
-
-    cmd._hidden = !!(opts.noHelp || opts.hidden); // noHelp is deprecated old name for hidden
-    cmd._hasHelpOption = this._hasHelpOption;
-    cmd._helpFlags = this._helpFlags;
-    cmd._helpDescription = this._helpDescription;
-    cmd._helpShortFlag = this._helpShortFlag;
-    cmd._helpLongFlag = this._helpLongFlag;
-    cmd._helpCommandName = this._helpCommandName;
-    cmd._helpCommandnameAndArgs = this._helpCommandnameAndArgs;
-    cmd._helpCommandDescription = this._helpCommandDescription;
-    cmd._helpConfiguration = this._helpConfiguration;
-    cmd._exitCallback = this._exitCallback;
-    cmd._storeOptionsAsProperties = this._storeOptionsAsProperties;
-    cmd._combineFlagAndOptionalValue = this._combineFlagAndOptionalValue;
-    cmd._allowExcessArguments = this._allowExcessArguments;
-    cmd._enablePositionalOptions = this._enablePositionalOptions;
-
-    cmd._executableFile = opts.executableFile || null; // Custom name for executable file, set missing to null to match constructor
-    this.commands.push(cmd);
-    cmd._parseExpectedArgs(args);
-    cmd.parent = this;
-
-    if (desc) return this;
-    return cmd;
-  };
+/**
+ * Add an implicit `help [cmd]` subcommand
+ * which invokes `--help` for the given command.
+ *
+ * @api private
+ */
 
-  /**
-   * Factory routine to create a new unattached command.
-   *
-   * See .command() for creating an attached subcommand, which uses this routine to
-   * create the command. You can override createCommand to customise subcommands.
-   *
-   * @param {string} [name]
-   * @return {Command} new command
-   */
+Command.prototype.addImplicitHelpCommand = function() {
+  this.command('help [cmd]', 'display help for [cmd]');
+};
 
-  createCommand(name) {
-    return new Command(name);
-  };
+/**
+ * Parse expected `args`.
+ *
+ * For example `["[type]"]` becomes `[{ required: false, name: 'type' }]`.
+ *
+ * @param {Array} args
+ * @return {Command} for chaining
+ * @api public
+ */
 
-  /**
-   * You can customise the help with a subclass of Help by overriding createHelp,
-   * or by overriding Help properties using configureHelp().
-   *
-   * @return {Help}
-   */
+Command.prototype.parseExpectedArgs = function(args) {
+  if (!args.length) return;
+  var self = this;
+  args.forEach(function(arg) {
+    var argDetails = {
+      required: false,
+      name: '',
+      variadic: false
+    };
 
-  createHelp() {
-    return Object.assign(new Help(), this.configureHelp());
-  };
+    switch (arg[0]) {
+      case '<':
+        argDetails.required = true;
+        argDetails.name = arg.slice(1, -1);
+        break;
+      case '[':
+        argDetails.name = arg.slice(1, -1);
+        break;
+    }
 
-  /**
-   * You can customise the help by overriding Help properties using configureHelp(),
-   * or with a subclass of Help by overriding createHelp().
-   *
-   * @param {Object} [configuration] - configuration options
-   * @return {Command|Object} `this` command for chaining, or stored configuration
-   */
+    if (argDetails.name.length > 3 && argDetails.name.slice(-3) === '...') {
+      argDetails.variadic = true;
+      argDetails.name = argDetails.name.slice(0, -3);
+    }
+    if (argDetails.name) {
+      self._args.push(argDetails);
+    }
+  });
+  return this;
+};
 
-  configureHelp(configuration) {
-    if (configuration === undefined) return this._helpConfiguration;
+/**
+ * Register callback to use as replacement for calling process.exit.
+ *
+ * @param {Function} [fn] optional callback which will be passed a CommanderError, defaults to throwing
+ * @return {Command} for chaining
+ * @api public
+ */
 
-    this._helpConfiguration = configuration;
-    return this;
+Command.prototype.exitOverride = function(fn) {
+  if (fn) {
+    this._exitCallback = fn;
+  } else {
+    this._exitCallback = function(err) {
+      if (err.code !== 'commander.executeSubCommandAsync') {
+        throw err;
+      } else {
+        // Async callback from spawn events, not useful to throw.
+      }
+    };
   }
+  return this;
+};
 
-  /**
-   * The default output goes to stdout and stderr. You can customise this for special
-   * applications. You can also customise the display of errors by overriding outputError.
-   *
-   * The configuration properties are all functions:
-   *
-   *    // functions to change where being written, stdout and stderr
-   *    writeOut(str)
-   *    writeErr(str)
-   *    // matching functions to specify width for wrapping help
-   *    getOutHelpWidth()
-   *    getErrHelpWidth()
-   *    // functions based on what is being written out
-   *    outputError(str, write) // used for displaying errors, and not used for displaying help
-   *
-   * @param {Object} [configuration] - configuration options
-   * @return {Command|Object} `this` command for chaining, or stored configuration
-   */
-
-  configureOutput(configuration) {
-    if (configuration === undefined) return this._outputConfiguration;
+/**
+ * Call process.exit, and _exitCallback if defined.
+ *
+ * @param {Number} exitCode exit code for using with process.exit
+ * @param {String} code an id string representing the error
+ * @param {String} message human-readable description of the error
+ * @return never
+ * @api private
+ */
 
-    Object.assign(this._outputConfiguration, configuration);
-    return this;
+Command.prototype._exit = function(exitCode, code, message) {
+  if (this._exitCallback) {
+    this._exitCallback(new CommanderError(exitCode, code, message));
+    // Expecting this line is not reached.
   }
+  process.exit(exitCode);
+};
 
-  /**
-   * Add a prepared subcommand.
-   *
-   * See .command() for creating an attached subcommand which inherits settings from its parent.
-   *
-   * @param {Command} cmd - new subcommand
-   * @param {Object} [opts] - configuration options
-   * @return {Command} `this` command for chaining
-   */
+/**
+ * Register callback `fn` for the command.
+ *
+ * Examples:
+ *
+ *      program
+ *        .command('help')
+ *        .description('display verbose help')
+ *        .action(function() {
+ *           // output help here
+ *        });
+ *
+ * @param {Function} fn
+ * @return {Command} for chaining
+ * @api public
+ */
 
-  addCommand(cmd, opts) {
-    if (!cmd._name) throw new Error('Command passed to .addCommand() must have a name');
+Command.prototype.action = function(fn) {
+  var self = this;
+  var listener = function(args, unknown) {
+    // Parse any so-far unknown options
+    args = args || [];
+    unknown = unknown || [];
 
-    // To keep things simple, block automatic name generation for deeply nested executables.
-    // Fail fast and detect when adding rather than later when parsing.
-    function checkExplicitNames(commandArray) {
-      commandArray.forEach((cmd) => {
-        if (cmd._executableHandler && !cmd._executableFile) {
-          throw new Error(`Must specify executableFile for deeply nested executable: ${cmd.name()}`);
-        }
-        checkExplicitNames(cmd.commands);
-      });
-    }
-    checkExplicitNames(cmd.commands);
+    var parsed = self.parseOptions(unknown);
 
-    opts = opts || {};
-    if (opts.isDefault) this._defaultCommandName = cmd._name;
-    if (opts.noHelp || opts.hidden) cmd._hidden = true; // modifying passed command due to existing implementation
+    // Output help if necessary
+    outputHelpIfRequested(self, parsed.unknown);
+    self._checkForMissingMandatoryOptions();
 
-    this.commands.push(cmd);
-    cmd.parent = this;
-    return this;
-  };
+    // If there are still any unknown options, then we simply
+    // die, unless someone asked for help, in which case we give it
+    // to them, and then we die.
+    if (parsed.unknown.length > 0) {
+      self.unknownOption(parsed.unknown[0]);
+    }
 
-  /**
-   * Define argument syntax for the command.
-   */
+    // Leftover arguments need to be pushed back. Fixes issue #56
+    if (parsed.args.length) args = parsed.args.concat(args);
 
-  arguments(desc) {
-    return this._parseExpectedArgs(desc.split(/ +/));
-  };
+    self._args.forEach(function(arg, i) {
+      if (arg.required && args[i] == null) {
+        self.missingArgument(arg.name);
+      } else if (arg.variadic) {
+        if (i !== self._args.length - 1) {
+          self.variadicArgNotLast(arg.name);
+        }
 
-  /**
-   * Override default decision whether to add implicit help command.
-   *
-   *    addHelpCommand() // force on
-   *    addHelpCommand(false); // force off
-   *    addHelpCommand('help [cmd]', 'display help for [cmd]'); // force on with custom details
-   *
-   * @return {Command} `this` command for chaining
-   */
+        args[i] = args.splice(i);
+      }
+    });
 
-  addHelpCommand(enableOrNameAndArgs, description) {
-    if (enableOrNameAndArgs === false) {
-      this._addImplicitHelpCommand = false;
+    // The .action callback takes an extra parameter which is the command itself.
+    var expectedArgsCount = self._args.length;
+    var actionArgs = args.slice(0, expectedArgsCount);
+    if (self._passCommandToAction) {
+      actionArgs[expectedArgsCount] = self;
     } else {
-      this._addImplicitHelpCommand = true;
-      if (typeof enableOrNameAndArgs === 'string') {
-        this._helpCommandName = enableOrNameAndArgs.split(' ')[0];
-        this._helpCommandnameAndArgs = enableOrNameAndArgs;
-      }
-      this._helpCommandDescription = description || this._helpCommandDescription;
+      actionArgs[expectedArgsCount] = self.opts();
+    }
+    // Add the extra arguments so available too.
+    if (args.length > expectedArgsCount) {
+      actionArgs.push(args.slice(expectedArgsCount));
     }
-    return this;
-  };
-
-  /**
-   * @return {boolean}
-   * @api private
-   */
 
-  _hasImplicitHelpCommand() {
-    if (this._addImplicitHelpCommand === undefined) {
-      return this.commands.length && !this._actionHandler && !this._findCommand('help');
+    const actionResult = fn.apply(self, actionArgs);
+    // Remember result in case it is async. Assume parseAsync getting called on root.
+    let rootCommand = self;
+    while (rootCommand.parent) {
+      rootCommand = rootCommand.parent;
     }
-    return this._addImplicitHelpCommand;
+    rootCommand._actionResults.push(actionResult);
   };
+  var parent = this.parent || this;
+  var name = parent === this ? '*' : this._name;
+  parent.on('command:' + name, listener);
+  if (this._alias) parent.on('command:' + this._alias, listener);
+  return this;
+};
 
-  /**
-   * Parse expected `args`.
-   *
-   * For example `["[type]"]` becomes `[{ required: false, name: 'type' }]`.
-   *
-   * @param {Array} args
-   * @return {Command} `this` command for chaining
-   * @api private
-   */
+/**
+ * Internal implementation shared by .option() and .requiredOption()
+ *
+ * @param {Object} config
+ * @param {String} flags
+ * @param {String} description
+ * @param {Function|*} [fn] - custom option processing function or default vaue
+ * @param {*} [defaultValue]
+ * @return {Command} for chaining
+ * @api private
+ */
 
-  _parseExpectedArgs(args) {
-    if (!args.length) return;
-    args.forEach((arg) => {
-      const argDetails = {
-        required: false,
-        name: '',
-        variadic: false
+Command.prototype._optionEx = function(config, flags, description, fn, defaultValue) {
+  var self = this,
+    option = new Option(flags, description),
+    oname = option.name(),
+    name = option.attributeName();
+  option.mandatory = !!config.mandatory;
+
+  // default as 3rd arg
+  if (typeof fn !== 'function') {
+    if (fn instanceof RegExp) {
+      // This is a bit simplistic (especially no error messages), and probably better handled by caller using custom option processing.
+      // No longer documented in README, but still present for backwards compatibility.
+      var regex = fn;
+      fn = function(val, def) {
+        var m = regex.exec(val);
+        return m ? m[0] : def;
       };
-
-      switch (arg[0]) {
-        case '<':
-          argDetails.required = true;
-          argDetails.name = arg.slice(1, -1);
-          break;
-        case '[':
-          argDetails.name = arg.slice(1, -1);
-          break;
-      }
-
-      if (argDetails.name.length > 3 && argDetails.name.slice(-3) === '...') {
-        argDetails.variadic = true;
-        argDetails.name = argDetails.name.slice(0, -3);
-      }
-      if (argDetails.name) {
-        this._args.push(argDetails);
-      }
-    });
-    this._args.forEach((arg, i) => {
-      if (arg.variadic && i < this._args.length - 1) {
-        throw new Error(`only the last argument can be variadic '${arg.name}'`);
-      }
-    });
-    return this;
-  };
-
-  /**
-   * Register callback to use as replacement for calling process.exit.
-   *
-   * @param {Function} [fn] optional callback which will be passed a CommanderError, defaults to throwing
-   * @return {Command} `this` command for chaining
-   */
-
-  exitOverride(fn) {
-    if (fn) {
-      this._exitCallback = fn;
     } else {
-      this._exitCallback = (err) => {
-        if (err.code !== 'commander.executeSubCommandAsync') {
-          throw err;
-        } else {
-          // Async callback from spawn events, not useful to throw.
-        }
-      };
+      defaultValue = fn;
+      fn = null;
     }
-    return this;
-  };
-
-  /**
-   * Call process.exit, and _exitCallback if defined.
-   *
-   * @param {number} exitCode exit code for using with process.exit
-   * @param {string} code an id string representing the error
-   * @param {string} message human-readable description of the error
-   * @return never
-   * @api private
-   */
+  }
 
-  _exit(exitCode, code, message) {
-    if (this._exitCallback) {
-      this._exitCallback(new CommanderError(exitCode, code, message));
-      // Expecting this line is not reached.
+  // preassign default value for --no-*, [optional], <required>, or plain flag if boolean value
+  if (option.negate || option.optional || option.required || typeof defaultValue === 'boolean') {
+    // when --no-foo we make sure default is true, unless a --foo option is already defined
+    if (option.negate) {
+      const positiveLongFlag = option.long.replace(/^--no-/, '--');
+      defaultValue = self.optionFor(positiveLongFlag) ? self._getOptionValue(name) : true;
     }
-    process.exit(exitCode);
-  };
+    // preassign only if we have a default
+    if (defaultValue !== undefined) {
+      self._setOptionValue(name, defaultValue);
+      option.defaultValue = defaultValue;
+    }
+  }
 
-  /**
-   * Register callback `fn` for the command.
-   *
-   * Examples:
-   *
-   *      program
-   *        .command('help')
-   *        .description('display verbose help')
-   *        .action(function() {
-   *           // output help here
-   *        });
-   *
-   * @param {Function} fn
-   * @return {Command} `this` command for chaining
-   */
+  // register the option
+  this.options.push(option);
 
-  action(fn) {
-    const listener = (args) => {
-      // The .action callback takes an extra parameter which is the command or options.
-      const expectedArgsCount = this._args.length;
-      const actionArgs = args.slice(0, expectedArgsCount);
-      if (this._storeOptionsAsProperties) {
-        actionArgs[expectedArgsCount] = this; // backwards compatible "options"
-      } else {
-        actionArgs[expectedArgsCount] = this.opts();
-      }
-      actionArgs.push(this);
+  // when it's passed assign the value
+  // and conditionally invoke the callback
+  this.on('option:' + oname, function(val) {
+    // coercion
+    if (val !== null && fn) {
+      val = fn(val, self._getOptionValue(name) === undefined ? defaultValue : self._getOptionValue(name));
+    }
 
-      const actionResult = fn.apply(this, actionArgs);
-      // Remember result in case it is async. Assume parseAsync getting called on root.
-      let rootCommand = this;
-      while (rootCommand.parent) {
-        rootCommand = rootCommand.parent;
+    // unassigned or boolean value
+    if (typeof self._getOptionValue(name) === 'boolean' || typeof self._getOptionValue(name) === 'undefined') {
+      // if no value, negate false, and we have a default, then use it!
+      if (val == null) {
+        self._setOptionValue(name, option.negate
+          ? false
+          : defaultValue || true);
+      } else {
+        self._setOptionValue(name, val);
       }
-      rootCommand._actionResults.push(actionResult);
-    };
-    this._actionHandler = listener;
-    return this;
-  };
+    } else if (val !== null) {
+      // reassign
+      self._setOptionValue(name, option.negate ? false : val);
+    }
+  });
 
-  /**
-   * Factory routine to create a new unattached option.
-   *
-   * See .option() for creating an attached option, which uses this routine to
-   * create the option. You can override createOption to return a custom option.
-   *
-   * @param {string} flags
-   * @param {string} [description]
-   * @return {Option} new option
-   */
+  return this;
+};
 
-  createOption(flags, description) {
-    return new Option(flags, description);
-  };
+/**
+ * Define option with `flags`, `description` and optional
+ * coercion `fn`.
+ *
+ * The `flags` string should contain both the short and long flags,
+ * separated by comma, a pipe or space. The following are all valid
+ * all will output this way when `--help` is used.
+ *
+ *    "-p, --pepper"
+ *    "-p|--pepper"
+ *    "-p --pepper"
+ *
+ * Examples:
+ *
+ *     // simple boolean defaulting to undefined
+ *     program.option('-p, --pepper', 'add pepper');
+ *
+ *     program.pepper
+ *     // => undefined
+ *
+ *     --pepper
+ *     program.pepper
+ *     // => true
+ *
+ *     // simple boolean defaulting to true (unless non-negated option is also defined)
+ *     program.option('-C, --no-cheese', 'remove cheese');
+ *
+ *     program.cheese
+ *     // => true
+ *
+ *     --no-cheese
+ *     program.cheese
+ *     // => false
+ *
+ *     // required argument
+ *     program.option('-C, --chdir <path>', 'change the working directory');
+ *
+ *     --chdir /tmp
+ *     program.chdir
+ *     // => "/tmp"
+ *
+ *     // optional argument
+ *     program.option('-c, --cheese [type]', 'add cheese [marble]');
+ *
+ * @param {String} flags
+ * @param {String} description
+ * @param {Function|*} [fn] - custom option processing function or default vaue
+ * @param {*} [defaultValue]
+ * @return {Command} for chaining
+ * @api public
+ */
 
-  /**
-   * Add an option.
-   *
-   * @param {Option} option
-   * @return {Command} `this` command for chaining
-   */
-  addOption(option) {
-    const oname = option.name();
-    const name = option.attributeName();
-
-    let defaultValue = option.defaultValue;
-
-    // preassign default value for --no-*, [optional], <required>, or plain flag if boolean value
-    if (option.negate || option.optional || option.required || typeof defaultValue === 'boolean') {
-      // when --no-foo we make sure default is true, unless a --foo option is already defined
-      if (option.negate) {
-        const positiveLongFlag = option.long.replace(/^--no-/, '--');
-        defaultValue = this._findOption(positiveLongFlag) ? this._getOptionValue(name) : true;
-      }
-      // preassign only if we have a default
-      if (defaultValue !== undefined) {
-        this._setOptionValue(name, defaultValue);
-      }
-    }
+Command.prototype.option = function(flags, description, fn, defaultValue) {
+  return this._optionEx({}, flags, description, fn, defaultValue);
+};
 
-    // register the option
-    this.options.push(option);
-
-    // when it's passed assign the value
-    // and conditionally invoke the callback
-    this.on('option:' + oname, (val) => {
-      const oldValue = this._getOptionValue(name);
-
-      // custom processing
-      if (val !== null && option.parseArg) {
-        try {
-          val = option.parseArg(val, oldValue === undefined ? defaultValue : oldValue);
-        } catch (err) {
-          if (err.code === 'commander.invalidOptionArgument') {
-            const message = `error: option '${option.flags}' argument '${val}' is invalid. ${err.message}`;
-            this._displayError(err.exitCode, err.code, message);
-          }
-          throw err;
-        }
-      } else if (val !== null && option.variadic) {
-        val = option._concatValue(val, oldValue);
-      }
+/*
+ * Add a required option which must have a value after parsing. This usually means
+ * the option must be specified on the command line. (Otherwise the same as .option().)
+ *
+ * The `flags` string should contain both the short and long flags, separated by comma, a pipe or space.
+ *
+ * @param {String} flags
+ * @param {String} description
+ * @param {Function|*} [fn] - custom option processing function or default vaue
+ * @param {*} [defaultValue]
+ * @return {Command} for chaining
+ * @api public
+ */
 
-      // unassigned or boolean value
-      if (typeof oldValue === 'boolean' || typeof oldValue === 'undefined') {
-        // if no value, negate false, and we have a default, then use it!
-        if (val == null) {
-          this._setOptionValue(name, option.negate
-            ? false
-            : defaultValue || true);
-        } else {
-          this._setOptionValue(name, val);
-        }
-      } else if (val !== null) {
-        // reassign
-        this._setOptionValue(name, option.negate ? false : val);
-      }
-    });
+Command.prototype.requiredOption = function(flags, description, fn, defaultValue) {
+  return this._optionEx({ mandatory: true }, flags, description, fn, defaultValue);
+};
 
-    return this;
-  }
+/**
+ * Allow unknown options on the command line.
+ *
+ * @param {Boolean} arg if `true` or omitted, no error will be thrown
+ * for unknown options.
+ * @api public
+ */
+Command.prototype.allowUnknownOption = function(arg) {
+  this._allowUnknownOption = arguments.length === 0 || arg;
+  return this;
+};
 
-  /**
-   * Internal implementation shared by .option() and .requiredOption()
-   *
-   * @api private
-   */
-  _optionEx(config, flags, description, fn, defaultValue) {
-    const option = this.createOption(flags, description);
-    option.makeOptionMandatory(!!config.mandatory);
-    if (typeof fn === 'function') {
-      option.default(defaultValue).argParser(fn);
-    } else if (fn instanceof RegExp) {
-      // deprecated
-      const regex = fn;
-      fn = (val, def) => {
-        const m = regex.exec(val);
-        return m ? m[0] : def;
-      };
-      option.default(defaultValue).argParser(fn);
-    } else {
-      option.default(fn);
-    }
+/**
+  * Whether to store option values as properties on command object,
+  * or store separately (specify false). In both cases the option values can be accessed using .opts().
+  *
+  * @param {boolean} value
+  * @return {Command} Command for chaining
+  * @api public
+  */
 
-    return this.addOption(option);
+Command.prototype.storeOptionsAsProperties = function(value) {
+  this._storeOptionsAsProperties = (value === undefined) || value;
+  if (this.options.length) {
+    // This is for programmer, not end user.
+    console.error('Commander usage error: call storeOptionsAsProperties before adding options');
   }
+  return this;
+};
 
-  /**
-   * Define option with `flags`, `description` and optional
-   * coercion `fn`.
-   *
-   * The `flags` string contains the short and/or long flags,
-   * separated by comma, a pipe or space. The following are all valid
-   * all will output this way when `--help` is used.
-   *
-   *    "-p, --pepper"
-   *    "-p|--pepper"
-   *    "-p --pepper"
-   *
-   * Examples:
-   *
-   *     // simple boolean defaulting to undefined
-   *     program.option('-p, --pepper', 'add pepper');
-   *
-   *     program.pepper
-   *     // => undefined
-   *
-   *     --pepper
-   *     program.pepper
-   *     // => true
-   *
-   *     // simple boolean defaulting to true (unless non-negated option is also defined)
-   *     program.option('-C, --no-cheese', 'remove cheese');
-   *
-   *     program.cheese
-   *     // => true
-   *
-   *     --no-cheese
-   *     program.cheese
-   *     // => false
-   *
-   *     // required argument
-   *     program.option('-C, --chdir <path>', 'change the working directory');
-   *
-   *     --chdir /tmp
-   *     program.chdir
-   *     // => "/tmp"
-   *
-   *     // optional argument
-   *     program.option('-c, --cheese [type]', 'add cheese [marble]');
-   *
-   * @param {string} flags
-   * @param {string} [description]
-   * @param {Function|*} [fn] - custom option processing function or default value
-   * @param {*} [defaultValue]
-   * @return {Command} `this` command for chaining
-   */
-
-  option(flags, description, fn, defaultValue) {
-    return this._optionEx({}, flags, description, fn, defaultValue);
-  };
-
-  /**
-  * Add a required option which must have a value after parsing. This usually means
-  * the option must be specified on the command line. (Otherwise the same as .option().)
-  *
-  * The `flags` string contains the short and/or long flags, separated by comma, a pipe or space.
+/**
+  * Whether to pass command to action handler,
+  * or just the options (specify false).
   *
-  * @param {string} flags
-  * @param {string} [description]
-  * @param {Function|*} [fn] - custom option processing function or default value
-  * @param {*} [defaultValue]
-  * @return {Command} `this` command for chaining
+  * @param {boolean} value
+  * @return {Command} Command for chaining
+  * @api public
   */
 
-  requiredOption(flags, description, fn, defaultValue) {
-    return this._optionEx({ mandatory: true }, flags, description, fn, defaultValue);
-  };
+Command.prototype.passCommandToAction = function(value) {
+  this._passCommandToAction = (value === undefined) || value;
+  return this;
+};
 
-  /**
-   * Alter parsing of short flags with optional values.
-   *
-   * Examples:
-   *
-   *    // for `.option('-f,--flag [value]'):
-   *    .combineFlagAndOptionalValue(true)  // `-f80` is treated like `--flag=80`, this is the default behaviour
-   *    .combineFlagAndOptionalValue(false) // `-fb` is treated like `-f -b`
-   *
-   * @param {Boolean} [combine=true] - if `true` or omitted, an optional value can be specified directly after the flag.
-   */
-  combineFlagAndOptionalValue(combine = true) {
-    this._combineFlagAndOptionalValue = !!combine;
-    return this;
-  };
+/**
+ * Store option value
+ *
+ * @param {String} key
+ * @param {Object} value
+ * @api private
+ */
 
-  /**
-   * Allow unknown options on the command line.
-   *
-   * @param {Boolean} [allowUnknown=true] - if `true` or omitted, no error will be thrown
-   * for unknown options.
-   */
-  allowUnknownOption(allowUnknown = true) {
-    this._allowUnknownOption = !!allowUnknown;
-    return this;
-  };
+Command.prototype._setOptionValue = function(key, value) {
+  if (this._storeOptionsAsProperties) {
+    this[key] = value;
+  } else {
+    this._optionValues[key] = value;
+  }
+};
 
-  /**
-   * Allow excess command-arguments on the command line. Pass false to make excess arguments an error.
-   *
-   * @param {Boolean} [allowExcess=true] - if `true` or omitted, no error will be thrown
-   * for excess arguments.
-   */
-  allowExcessArguments(allowExcess = true) {
-    this._allowExcessArguments = !!allowExcess;
-    return this;
-  };
+/**
+ * Retrieve option value
+ *
+ * @param {String} key
+ * @return {Object} value
+ * @api private
+ */
 
-  /**
-   * Enable positional options. Positional means global options are specified before subcommands which lets
-   * subcommands reuse the same option names, and also enables subcommands to turn on passThroughOptions.
-   * The default behaviour is non-positional and global options may appear anywhere on the command line.
-   *
-   * @param {Boolean} [positional=true]
-   */
-  enablePositionalOptions(positional = true) {
-    this._enablePositionalOptions = !!positional;
-    return this;
-  };
+Command.prototype._getOptionValue = function(key) {
+  if (this._storeOptionsAsProperties) {
+    return this[key];
+  }
+  return this._optionValues[key];
+};
 
-  /**
-   * Pass through options that come after command-arguments rather than treat them as command-options,
-   * so actual command-options come before command-arguments. Turning this on for a subcommand requires
-   * positional options to have been enabled on the program (parent commands).
-   * The default behaviour is non-positional and options may appear before or after command-arguments.
-   *
-   * @param {Boolean} [passThrough=true]
-   * for unknown options.
-   */
-  passThroughOptions(passThrough = true) {
-    this._passThroughOptions = !!passThrough;
-    if (!!this.parent && passThrough && !this.parent._enablePositionalOptions) {
-      throw new Error('passThroughOptions can not be used without turning on enablePositionalOptions for parent command(s)');
-    }
-    return this;
-  };
+/**
+ * Parse `argv`, setting options and invoking commands when defined.
+ *
+ * @param {Array} argv
+ * @return {Command} for chaining
+ * @api public
+ */
 
-  /**
-    * Whether to store option values as properties on command object,
-    * or store separately (specify false). In both cases the option values can be accessed using .opts().
-    *
-    * @param {boolean} [storeAsProperties=true]
-    * @return {Command} `this` command for chaining
-    */
-
-  storeOptionsAsProperties(storeAsProperties = true) {
-    this._storeOptionsAsProperties = !!storeAsProperties;
-    if (this.options.length) {
-      throw new Error('call .storeOptionsAsProperties() before adding options');
-    }
-    return this;
-  };
+Command.prototype.parse = function(argv) {
+  // implicit help
+  if (this.executables) this.addImplicitHelpCommand();
 
-  /**
-   * Store option value
-   *
-   * @param {string} key
-   * @param {Object} value
-   * @api private
-   */
+  // store raw args
+  this.rawArgs = argv;
 
-  _setOptionValue(key, value) {
-    if (this._storeOptionsAsProperties) {
-      this[key] = value;
-    } else {
-      this._optionValues[key] = value;
-    }
-  };
+  // guess name
+  this._name = this._name || basename(argv[1], '.js');
 
-  /**
-   * Retrieve option value
-   *
-   * @param {string} key
-   * @return {Object} value
-   * @api private
-   */
+  // github-style sub-commands with no sub-command
+  if (this.executables && argv.length < 3 && !this.defaultExecutable) {
+    // this user needs help
+    argv.push(this._helpLongFlag);
+  }
 
-  _getOptionValue(key) {
-    if (this._storeOptionsAsProperties) {
-      return this[key];
-    }
-    return this._optionValues[key];
-  };
+  // process argv
+  var normalized = this.normalize(argv.slice(2));
+  var parsed = this.parseOptions(normalized);
+  var args = this.args = parsed.args;
 
-  /**
-   * Parse `argv`, setting options and invoking commands when defined.
-   *
-   * The default expectation is that the arguments are from node and have the application as argv[0]
-   * and the script being run in argv[1], with user parameters after that.
-   *
-   * Examples:
-   *
-   *      program.parse(process.argv);
-   *      program.parse(); // implicitly use process.argv and auto-detect node vs electron conventions
-   *      program.parse(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
-   *
-   * @param {string[]} [argv] - optional, defaults to process.argv
-   * @param {Object} [parseOptions] - optionally specify style of options with from: node/user/electron
-   * @param {string} [parseOptions.from] - where the args are from: 'node', 'user', 'electron'
-   * @return {Command} `this` command for chaining
-   */
+  var result = this.parseArgs(this.args, parsed.unknown);
 
-  parse(argv, parseOptions) {
-    if (argv !== undefined && !Array.isArray(argv)) {
-      throw new Error('first parameter to parse must be array or undefined');
-    }
-    parseOptions = parseOptions || {};
-
-    // Default to using process.argv
-    if (argv === undefined) {
-      argv = process.argv;
-      // @ts-ignore: unknown property
-      if (process.versions && process.versions.electron) {
-        parseOptions.from = 'electron';
-      }
-    }
-    this.rawArgs = argv.slice();
-
-    // make it a little easier for callers by supporting various argv conventions
-    let userArgs;
-    switch (parseOptions.from) {
-      case undefined:
-      case 'node':
-        this._scriptPath = argv[1];
-        userArgs = argv.slice(2);
-        break;
-      case 'electron':
-        // @ts-ignore: unknown property
-        if (process.defaultApp) {
-          this._scriptPath = argv[1];
-          userArgs = argv.slice(2);
-        } else {
-          userArgs = argv.slice(1);
-        }
-        break;
-      case 'user':
-        userArgs = argv.slice(0);
-        break;
-      default:
-        throw new Error(`unexpected parse option { from: '${parseOptions.from}' }`);
-    }
-    if (!this._scriptPath && require.main) {
-      this._scriptPath = require.main.filename;
-    }
+  if (args[0] === 'help' && args.length === 1) this.help();
 
-    // Guess name, used in usage in help.
-    this._name = this._name || (this._scriptPath && path.basename(this._scriptPath, path.extname(this._scriptPath)));
+  // Note for future: we could return early if we found an action handler in parseArgs, as none of following code needed?
 
-    // Let's go!
-    this._parseCommand([], userArgs);
+  // <cmd> --help
+  if (args[0] === 'help') {
+    args[0] = args[1];
+    args[1] = this._helpLongFlag;
+  } else {
+    // If calling through to executable subcommand we could check for help flags before failing,
+    // but a somewhat unlikely case since program options not passed to executable subcommands.
+    // Wait for reports to see if check needed and what usage pattern is.
+    this._checkForMissingMandatoryOptions();
+  }
 
-    return this;
-  };
+  // executable sub-commands
+  // (Debugging note for future: args[0] is not right if an action has been called)
+  var name = result.args[0];
+  var subCommand = null;
 
-  /**
-   * Parse `argv`, setting options and invoking commands when defined.
-   *
-   * Use parseAsync instead of parse if any of your action handlers are async. Returns a Promise.
-   *
-   * The default expectation is that the arguments are from node and have the application as argv[0]
-   * and the script being run in argv[1], with user parameters after that.
-   *
-   * Examples:
-   *
-   *      program.parseAsync(process.argv);
-   *      program.parseAsync(); // implicitly use process.argv and auto-detect node vs electron conventions
-   *      program.parseAsync(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
-   *
-   * @param {string[]} [argv]
-   * @param {Object} [parseOptions]
-   * @param {string} parseOptions.from - where the args are from: 'node', 'user', 'electron'
-   * @return {Promise}
-   */
+  // Look for subcommand
+  if (name) {
+    subCommand = this.commands.find(function(command) {
+      return command._name === name;
+    });
+  }
 
-  parseAsync(argv, parseOptions) {
-    this.parse(argv, parseOptions);
-    return Promise.all(this._actionResults).then(() => this);
-  };
+  // Look for alias
+  if (!subCommand && name) {
+    subCommand = this.commands.find(function(command) {
+      return command.alias() === name;
+    });
+    if (subCommand) {
+      name = subCommand._name;
+      args[0] = name;
+    }
+  }
 
-  /**
-   * Execute a sub-command executable.
-   *
-   * @api private
-   */
+  // Look for default subcommand
+  if (!subCommand && this.defaultExecutable) {
+    name = this.defaultExecutable;
+    args.unshift(name);
+    subCommand = this.commands.find(function(command) {
+      return command._name === name;
+    });
+  }
 
-  _executeSubCommand(subcommand, args) {
-    args = args.slice();
-    let launchWithNode = false; // Use node for source targets so do not need to get permissions correct, and on Windows.
-    const sourceExt = ['.js', '.ts', '.tsx', '.mjs', '.cjs'];
+  if (this._execs.has(name)) {
+    return this.executeSubCommand(argv, args, parsed.unknown, subCommand ? subCommand._executableFile : undefined);
+  }
 
-    // Not checking for help first. Unlikely to have mandatory and executable, and can't robustly test for help flags in external command.
-    this._checkForMissingMandatoryOptions();
+  return result;
+};
 
-    // Want the entry script as the reference for command name and directory for searching for other files.
-    let scriptPath = this._scriptPath;
-    // Fallback in case not set, due to how Command created or called.
-    if (!scriptPath && require.main) {
-      scriptPath = require.main.filename;
-    }
+/**
+ * Parse `argv`, setting options and invoking commands when defined.
+ *
+ * Use parseAsync instead of parse if any of your action handlers are async. Returns a Promise.
+ *
+ * @param {Array} argv
+ * @return {Promise}
+ * @api public
+ */
+Command.prototype.parseAsync = function(argv) {
+  this.parse(argv);
+  return Promise.all(this._actionResults);
+};
 
-    let baseDir;
-    try {
-      const resolvedLink = fs.realpathSync(scriptPath);
-      baseDir = path.dirname(resolvedLink);
-    } catch (e) {
-      baseDir = '.'; // dummy, probably not going to find executable!
-    }
+/**
+ * Execute a sub-command executable.
+ *
+ * @param {Array} argv
+ * @param {Array} args
+ * @param {Array} unknown
+ * @param {String} executableFile
+ * @api private
+ */
 
-    // name of the subcommand, like `pm-install`
-    let bin = path.basename(scriptPath, path.extname(scriptPath)) + '-' + subcommand._name;
-    if (subcommand._executableFile) {
-      bin = subcommand._executableFile;
-    }
+Command.prototype.executeSubCommand = function(argv, args, unknown, executableFile) {
+  args = args.concat(unknown);
 
-    const localBin = path.join(baseDir, bin);
-    if (fs.existsSync(localBin)) {
-      // prefer local `./<bin>` to bin in the $PATH
-      bin = localBin;
-    } else {
-      // Look for source files.
-      sourceExt.forEach((ext) => {
-        if (fs.existsSync(`${localBin}${ext}`)) {
-          bin = `${localBin}${ext}`;
-        }
-      });
-    }
-    launchWithNode = sourceExt.includes(path.extname(bin));
+  if (!args.length) this.help();
 
-    let proc;
-    if (process.platform !== 'win32') {
-      if (launchWithNode) {
-        args.unshift(bin);
-        // add executable arguments to spawn
-        args = incrementNodeInspectorPort(process.execArgv).concat(args);
+  var isExplicitJS = false; // Whether to use node to launch "executable"
 
-        proc = childProcess.spawn(process.argv[0], args, { stdio: 'inherit' });
-      } else {
-        proc = childProcess.spawn(bin, args, { stdio: 'inherit' });
-      }
-    } else {
+  // executable
+  var pm = argv[1];
+  // name of the subcommand, like `pm-install`
+  var bin = basename(pm, path.extname(pm)) + '-' + args[0];
+  if (executableFile != null) {
+    bin = executableFile;
+    // Check for same extensions as we scan for below so get consistent launch behaviour.
+    var executableExt = path.extname(executableFile);
+    isExplicitJS = executableExt === '.js' || executableExt === '.ts' || executableExt === '.mjs';
+  }
+
+  // In case of globally installed, get the base dir where executable
+  //  subcommand file should be located at
+  var baseDir;
+
+  var resolvedLink = fs.realpathSync(pm);
+
+  baseDir = dirname(resolvedLink);
+
+  // prefer local `./<bin>` to bin in the $PATH
+  var localBin = path.join(baseDir, bin);
+
+  // whether bin file is a js script with explicit `.js` or `.ts` extension
+  if (exists(localBin + '.js')) {
+    bin = localBin + '.js';
+    isExplicitJS = true;
+  } else if (exists(localBin + '.ts')) {
+    bin = localBin + '.ts';
+    isExplicitJS = true;
+  } else if (exists(localBin + '.mjs')) {
+    bin = localBin + '.mjs';
+    isExplicitJS = true;
+  } else if (exists(localBin)) {
+    bin = localBin;
+  }
+
+  args = args.slice(1);
+
+  var proc;
+  if (process.platform !== 'win32') {
+    if (isExplicitJS) {
       args.unshift(bin);
       // add executable arguments to spawn
       args = incrementNodeInspectorPort(process.execArgv).concat(args);
-      proc = childProcess.spawn(process.execPath, args, { stdio: 'inherit' });
+
+      proc = spawn(process.argv[0], args, { stdio: 'inherit' });
+    } else {
+      proc = spawn(bin, args, { stdio: 'inherit' });
     }
+  } else {
+    args.unshift(bin);
+    // add executable arguments to spawn
+    args = incrementNodeInspectorPort(process.execArgv).concat(args);
+    proc = spawn(process.execPath, args, { stdio: 'inherit' });
+  }
 
-    const signals = ['SIGUSR1', 'SIGUSR2', 'SIGTERM', 'SIGINT', 'SIGHUP'];
-    signals.forEach((signal) => {
-      // @ts-ignore
-      process.on(signal, () => {
-        if (proc.killed === false && proc.exitCode === null) {
-          proc.kill(signal);
-        }
-      });
+  var signals = ['SIGUSR1', 'SIGUSR2', 'SIGTERM', 'SIGINT', 'SIGHUP'];
+  signals.forEach(function(signal) {
+    process.on(signal, function() {
+      if (proc.killed === false && proc.exitCode === null) {
+        proc.kill(signal);
+      }
     });
+  });
 
-    // By default terminate process when spawned process terminates.
-    // Suppressing the exit if exitCallback defined is a bit messy and of limited use, but does allow process to stay running!
-    const exitCallback = this._exitCallback;
+  // By default terminate process when spawned process terminates.
+  // Suppressing the exit if exitCallback defined is a bit messy and of limited use, but does allow process to stay running!
+  const exitCallback = this._exitCallback;
+  if (!exitCallback) {
+    proc.on('close', process.exit.bind(process));
+  } else {
+    proc.on('close', () => {
+      exitCallback(new CommanderError(process.exitCode || 0, 'commander.executeSubCommandAsync', '(close)'));
+    });
+  }
+  proc.on('error', function(err) {
+    if (err.code === 'ENOENT') {
+      console.error('error: %s(1) does not exist, try --help', bin);
+    } else if (err.code === 'EACCES') {
+      console.error('error: %s(1) not executable. try chmod or run with root', bin);
+    }
     if (!exitCallback) {
-      proc.on('close', process.exit.bind(process));
+      process.exit(1);
     } else {
-      proc.on('close', () => {
-        exitCallback(new CommanderError(process.exitCode || 0, 'commander.executeSubCommandAsync', '(close)'));
-      });
+      const wrappedError = new CommanderError(1, 'commander.executeSubCommandAsync', '(error)');
+      wrappedError.nestedError = err;
+      exitCallback(wrappedError);
     }
-    proc.on('error', (err) => {
-      // @ts-ignore
-      if (err.code === 'ENOENT') {
-        const executableMissing = `'${bin}' does not exist
- - if '${subcommand._name}' is not meant to be an executable command, remove description parameter from '.command()' and use '.description()' instead
- - if the default executable name is not suitable, use the executableFile option to supply a custom name`;
-        throw new Error(executableMissing);
-      // @ts-ignore
-      } else if (err.code === 'EACCES') {
-        throw new Error(`'${bin}' not executable`);
-      }
-      if (!exitCallback) {
-        process.exit(1);
-      } else {
-        const wrappedError = new CommanderError(1, 'commander.executeSubCommandAsync', '(error)');
-        wrappedError.nestedError = err;
-        exitCallback(wrappedError);
-      }
-    });
+  });
 
-    // Store the reference to the child process
-    this.runningCommand = proc;
-  };
+  // Store the reference to the child process
+  this.runningCommand = proc;
+};
 
-  /**
-   * @api private
-   */
-  _dispatchSubcommand(commandName, operands, unknown) {
-    const subCommand = this._findCommand(commandName);
-    if (!subCommand) this.help({ error: true });
+/**
+ * Normalize `args`, splitting joined short flags. For example
+ * the arg "-abc" is equivalent to "-a -b -c".
+ * This also normalizes equal sign and splits "--abc=def" into "--abc def".
+ *
+ * @param {Array} args
+ * @return {Array}
+ * @api private
+ */
 
-    if (subCommand._executableHandler) {
-      this._executeSubCommand(subCommand, operands.concat(unknown));
-    } else {
-      subCommand._parseCommand(operands, unknown);
+Command.prototype.normalize = function(args) {
+  var ret = [],
+    arg,
+    lastOpt,
+    index,
+    short,
+    opt;
+
+  for (var i = 0, len = args.length; i < len; ++i) {
+    arg = args[i];
+    if (i > 0) {
+      lastOpt = this.optionFor(args[i - 1]);
     }
-  };
 
-  /**
-   * Process arguments in context of this command.
-   *
-   * @api private
-   */
-
-  _parseCommand(operands, unknown) {
-    const parsed = this.parseOptions(unknown);
-    operands = operands.concat(parsed.operands);
-    unknown = parsed.unknown;
-    this.args = operands.concat(unknown);
-
-    if (operands && this._findCommand(operands[0])) {
-      this._dispatchSubcommand(operands[0], operands.slice(1), unknown);
-    } else if (this._hasImplicitHelpCommand() && operands[0] === this._helpCommandName) {
-      if (operands.length === 1) {
-        this.help();
+    if (arg === '--') {
+      // Honor option terminator
+      ret = ret.concat(args.slice(i));
+      break;
+    } else if (lastOpt && lastOpt.required) {
+      ret.push(arg);
+    } else if (arg.length > 2 && arg[0] === '-' && arg[1] !== '-') {
+      short = arg.slice(0, 2);
+      opt = this.optionFor(short);
+      if (opt && (opt.required || opt.optional)) {
+        ret.push(short);
+        ret.push(arg.slice(2));
       } else {
-        this._dispatchSubcommand(operands[1], [], [this._helpLongFlag]);
+        arg.slice(1).split('').forEach(function(c) {
+          ret.push('-' + c);
+        });
       }
-    } else if (this._defaultCommandName) {
-      outputHelpIfRequested(this, unknown); // Run the help for default command from parent rather than passing to default command
-      this._dispatchSubcommand(this._defaultCommandName, operands, unknown);
+    } else if (/^--/.test(arg) && ~(index = arg.indexOf('='))) {
+      ret.push(arg.slice(0, index), arg.slice(index + 1));
     } else {
-      if (this.commands.length && this.args.length === 0 && !this._actionHandler && !this._defaultCommandName) {
-        // probably missing subcommand and no handler, user needs help
-        this.help({ error: true });
-      }
+      ret.push(arg);
+    }
+  }
 
-      outputHelpIfRequested(this, parsed.unknown);
-      this._checkForMissingMandatoryOptions();
+  return ret;
+};
 
-      // We do not always call this check to avoid masking a "better" error, like unknown command.
-      const checkForUnknownOptions = () => {
-        if (parsed.unknown.length > 0) {
-          this.unknownOption(parsed.unknown[0]);
-        }
-      };
+/**
+ * Parse command `args`.
+ *
+ * When listener(s) are available those
+ * callbacks are invoked, otherwise the "*"
+ * event is emitted and those actions are invoked.
+ *
+ * @param {Array} args
+ * @return {Command} for chaining
+ * @api private
+ */
 
-      const commandEvent = `command:${this.name()}`;
-      if (this._actionHandler) {
-        checkForUnknownOptions();
-        // Check expected arguments and collect variadic together.
-        const args = this.args.slice();
-        this._args.forEach((arg, i) => {
-          if (arg.required && args[i] == null) {
-            this.missingArgument(arg.name);
-          } else if (arg.variadic) {
-            args[i] = args.splice(i);
-            args.length = Math.min(i + 1, args.length);
-          }
-        });
-        if (args.length > this._args.length) {
-          this._excessArguments(args);
-        }
+Command.prototype.parseArgs = function(args, unknown) {
+  var name;
 
-        this._actionHandler(args);
-        if (this.parent) this.parent.emit(commandEvent, operands, unknown); // legacy
-      } else if (this.parent && this.parent.listenerCount(commandEvent)) {
-        checkForUnknownOptions();
-        this.parent.emit(commandEvent, operands, unknown); // legacy
-      } else if (operands.length) {
-        if (this._findCommand('*')) { // legacy default command
-          this._dispatchSubcommand('*', operands, unknown);
-        } else if (this.listenerCount('command:*')) {
-          // skip option check, emit event for possible misspelling suggestion
-          this.emit('command:*', operands, unknown);
-        } else if (this.commands.length) {
-          this.unknownCommand();
-        } else {
-          checkForUnknownOptions();
-        }
-      } else if (this.commands.length) {
-        // This command has subcommands and nothing hooked up at this level, so display help.
-        this.help({ error: true });
-      } else {
-        checkForUnknownOptions();
-        // fall through for caller to handle after calling .parse()
-      }
+  if (args.length) {
+    name = args[0];
+    if (this.listeners('command:' + name).length) {
+      this.emit('command:' + args.shift(), args, unknown);
+    } else {
+      this.emit('command:*', args, unknown);
     }
-  };
+  } else {
+    outputHelpIfRequested(this, unknown);
 
-  /**
-   * Find matching command.
-   *
-   * @api private
-   */
-  _findCommand(name) {
-    if (!name) return undefined;
-    return this.commands.find(cmd => cmd._name === name || cmd._aliases.includes(name));
-  };
-
-  /**
-   * Return an option matching `arg` if any.
-   *
-   * @param {string} arg
-   * @return {Option}
-   * @api private
-   */
+    // If there were no args and we have unknown options,
+    // then they are extraneous and we need to error.
+    if (unknown.length > 0 && !this.defaultExecutable) {
+      this.unknownOption(unknown[0]);
+    }
+    if (this.commands.length === 0 &&
+        this._args.filter(function(a) { return a.required; }).length === 0) {
+      this.emit('command:*');
+    }
+  }
 
-  _findOption(arg) {
-    return this.options.find(option => option.is(arg));
-  };
+  return this;
+};
 
-  /**
-   * Display an error message if a mandatory option does not have a value.
-   * Lazy calling after checking for help flags from leaf subcommand.
-   *
-   * @api private
-   */
+/**
+ * Return an option matching `arg` if any.
+ *
+ * @param {String} arg
+ * @return {Option}
+ * @api private
+ */
 
-  _checkForMissingMandatoryOptions() {
-    // Walk up hierarchy so can call in subcommand after checking for displaying help.
-    for (let cmd = this; cmd; cmd = cmd.parent) {
-      cmd.options.forEach((anOption) => {
-        if (anOption.mandatory && (cmd._getOptionValue(anOption.attributeName()) === undefined)) {
-          cmd.missingMandatoryOptionValue(anOption);
-        }
-      });
+Command.prototype.optionFor = function(arg) {
+  for (var i = 0, len = this.options.length; i < len; ++i) {
+    if (this.options[i].is(arg)) {
+      return this.options[i];
     }
-  };
+  }
+};
 
-  /**
-   * Parse options from `argv` removing known options,
-   * and return argv split into operands and unknown arguments.
-   *
-   * Examples:
-   *
-   *    argv => operands, unknown
-   *    --known kkk op => [op], []
-   *    op --known kkk => [op], []
-   *    sub --unknown uuu op => [sub], [--unknown uuu op]
-   *    sub -- --unknown uuu op => [sub --unknown uuu op], []
-   *
-   * @param {String[]} argv
-   * @return {{operands: String[], unknown: String[]}}
-   */
+/**
+ * Display an error message if a mandatory option does not have a value.
+ *
+ * @api private
+ */
 
-  parseOptions(argv) {
-    const operands = []; // operands, not options or values
-    const unknown = []; // first unknown option and remaining unknown args
-    let dest = operands;
-    const args = argv.slice();
+Command.prototype._checkForMissingMandatoryOptions = function() {
+  // Walk up hierarchy so can call from action handler after checking for displaying help.
+  for (var cmd = this; cmd; cmd = cmd.parent) {
+    cmd.options.forEach((anOption) => {
+      if (anOption.mandatory && (cmd._getOptionValue(anOption.attributeName()) === undefined)) {
+        cmd.missingMandatoryOptionValue(anOption);
+      }
+    });
+  }
+};
 
-    function maybeOption(arg) {
-      return arg.length > 1 && arg[0] === '-';
-    }
+/**
+ * Parse options from `argv` returning `argv`
+ * void of these options.
+ *
+ * @param {Array} argv
+ * @return {{args: Array, unknown: Array}}
+ * @api public
+ */
 
-    // parse options
-    let activeVariadicOption = null;
-    while (args.length) {
-      const arg = args.shift();
+Command.prototype.parseOptions = function(argv) {
+  var args = [],
+    len = argv.length,
+    literal,
+    option,
+    arg;
 
-      // literal
-      if (arg === '--') {
-        if (dest === unknown) dest.push(arg);
-        dest.push(...args);
-        break;
-      }
+  var unknownOptions = [];
 
-      if (activeVariadicOption && !maybeOption(arg)) {
-        this.emit(`option:${activeVariadicOption.name()}`, arg);
-        continue;
-      }
-      activeVariadicOption = null;
-
-      if (maybeOption(arg)) {
-        const option = this._findOption(arg);
-        // recognised option, call listener to assign value with possible custom processing
-        if (option) {
-          if (option.required) {
-            const value = args.shift();
-            if (value === undefined) this.optionMissingArgument(option);
-            this.emit(`option:${option.name()}`, value);
-          } else if (option.optional) {
-            let value = null;
-            // historical behaviour is optional value is following arg unless an option
-            if (args.length > 0 && !maybeOption(args[0])) {
-              value = args.shift();
-            }
-            this.emit(`option:${option.name()}`, value);
-          } else { // boolean flag
-            this.emit(`option:${option.name()}`);
-          }
-          activeVariadicOption = option.variadic ? option : null;
-          continue;
-        }
-      }
+  // parse options
+  for (var i = 0; i < len; ++i) {
+    arg = argv[i];
 
-      // Look for combo options following single dash, eat first one if known.
-      if (arg.length > 2 && arg[0] === '-' && arg[1] !== '-') {
-        const option = this._findOption(`-${arg[1]}`);
-        if (option) {
-          if (option.required || (option.optional && this._combineFlagAndOptionalValue)) {
-            // option with value following in same argument
-            this.emit(`option:${option.name()}`, arg.slice(2));
-          } else {
-            // boolean option, emit and put back remainder of arg for further processing
-            this.emit(`option:${option.name()}`);
-            args.unshift(`-${arg.slice(2)}`);
-          }
-          continue;
-        }
-      }
+    // literal args after --
+    if (literal) {
+      args.push(arg);
+      continue;
+    }
+
+    if (arg === '--') {
+      literal = true;
+      continue;
+    }
 
-      // Look for known long flag with value, like --foo=bar
-      if (/^--[^=]+=/.test(arg)) {
-        const index = arg.indexOf('=');
-        const option = this._findOption(arg.slice(0, index));
-        if (option && (option.required || option.optional)) {
-          this.emit(`option:${option.name()}`, arg.slice(index + 1));
-          continue;
+    // find matching Option
+    option = this.optionFor(arg);
+
+    // option is defined
+    if (option) {
+      // requires arg
+      if (option.required) {
+        arg = argv[++i];
+        if (arg == null) return this.optionMissingArgument(option);
+        this.emit('option:' + option.name(), arg);
+      // optional arg
+      } else if (option.optional) {
+        arg = argv[i + 1];
+        if (arg == null || (arg[0] === '-' && arg !== '-')) {
+          arg = null;
+        } else {
+          ++i;
         }
+        this.emit('option:' + option.name(), arg);
+      // flag
+      } else {
+        this.emit('option:' + option.name());
       }
+      continue;
+    }
 
-      // Not a recognised option by this command.
-      // Might be a command-argument, or subcommand option, or unknown option, or help command or option.
+    // looks like an option
+    if (arg.length > 1 && arg[0] === '-') {
+      unknownOptions.push(arg);
 
-      // An unknown option means further arguments also classified as unknown so can be reprocessed by subcommands.
-      if (maybeOption(arg)) {
-        dest = unknown;
+      // If the next argument looks like it might be
+      // an argument for this option, we pass it on.
+      // If it isn't, then it'll simply be ignored
+      if ((i + 1) < argv.length && (argv[i + 1][0] !== '-' || argv[i + 1] === '-')) {
+        unknownOptions.push(argv[++i]);
       }
+      continue;
+    }
 
-      // If using positionalOptions, stop processing our options at subcommand.
-      if ((this._enablePositionalOptions || this._passThroughOptions) && operands.length === 0 && unknown.length === 0) {
-        if (this._findCommand(arg)) {
-          operands.push(arg);
-          if (args.length > 0) unknown.push(...args);
-          break;
-        } else if (arg === this._helpCommandName && this._hasImplicitHelpCommand()) {
-          operands.push(arg);
-          if (args.length > 0) operands.push(...args);
-          break;
-        } else if (this._defaultCommandName) {
-          unknown.push(arg);
-          if (args.length > 0) unknown.push(...args);
-          break;
-        }
-      }
+    // arg
+    args.push(arg);
+  }
 
-      // If using passThroughOptions, stop processing options at first command-argument.
-      if (this._passThroughOptions) {
-        dest.push(arg);
-        if (args.length > 0) dest.push(...args);
-        break;
-      }
+  return { args: args, unknown: unknownOptions };
+};
 
-      // add arg
-      dest.push(arg);
+/**
+ * Return an object containing options as key-value pairs
+ *
+ * @return {Object}
+ * @api public
+ */
+Command.prototype.opts = function() {
+  if (this._storeOptionsAsProperties) {
+    // Preserve original behaviour so backwards compatible when still using properties
+    var result = {},
+      len = this.options.length;
+
+    for (var i = 0; i < len; i++) {
+      var key = this.options[i].attributeName();
+      result[key] = key === this._versionOptionName ? this._version : this[key];
     }
+    return result;
+  }
 
-    return { operands, unknown };
-  };
+  return this._optionValues;
+};
 
-  /**
-   * Return an object containing options as key-value pairs
-   *
-   * @return {Object}
-   */
-  opts() {
-    if (this._storeOptionsAsProperties) {
-      // Preserve original behaviour so backwards compatible when still using properties
-      const result = {};
-      const len = this.options.length;
-
-      for (let i = 0; i < len; i++) {
-        const key = this.options[i].attributeName();
-        result[key] = key === this._versionOptionName ? this._version : this[key];
-      }
-      return result;
-    }
+/**
+ * Argument `name` is missing.
+ *
+ * @param {String} name
+ * @api private
+ */
 
-    return this._optionValues;
-  };
+Command.prototype.missingArgument = function(name) {
+  const message = `error: missing required argument '${name}'`;
+  console.error(message);
+  this._exit(1, 'commander.missingArgument', message);
+};
 
-  /**
-   * Internal bottleneck for handling of parsing errors.
-   *
-   * @api private
-   */
-  _displayError(exitCode, code, message) {
-    this._outputConfiguration.outputError(`${message}\n`, this._outputConfiguration.writeErr);
-    this._exit(exitCode, code, message);
+/**
+ * `Option` is missing an argument, but received `flag` or nothing.
+ *
+ * @param {Option} option
+ * @param {String} [flag]
+ * @api private
+ */
+
+Command.prototype.optionMissingArgument = function(option, flag) {
+  let message;
+  if (flag) {
+    message = `error: option '${option.flags}' argument missing, got '${flag}'`;
+  } else {
+    message = `error: option '${option.flags}' argument missing`;
   }
+  console.error(message);
+  this._exit(1, 'commander.optionMissingArgument', message);
+};
 
-  /**
-   * Argument `name` is missing.
-   *
-   * @param {string} name
-   * @api private
-   */
+/**
+ * `Option` does not have a value, and is a mandatory option.
+ *
+ * @param {Option} option
+ * @api private
+ */
 
-  missingArgument(name) {
-    const message = `error: missing required argument '${name}'`;
-    this._displayError(1, 'commander.missingArgument', message);
-  };
+Command.prototype.missingMandatoryOptionValue = function(option) {
+  const message = `error: required option '${option.flags}' not specified`;
+  console.error(message);
+  this._exit(1, 'commander.missingMandatoryOptionValue', message);
+};
 
-  /**
-   * `Option` is missing an argument.
-   *
-   * @param {Option} option
-   * @api private
-   */
+/**
+ * Unknown option `flag`.
+ *
+ * @param {String} flag
+ * @api private
+ */
 
-  optionMissingArgument(option) {
-    const message = `error: option '${option.flags}' argument missing`;
-    this._displayError(1, 'commander.optionMissingArgument', message);
-  };
+Command.prototype.unknownOption = function(flag) {
+  if (this._allowUnknownOption) return;
+  const message = `error: unknown option '${flag}'`;
+  console.error(message);
+  this._exit(1, 'commander.unknownOption', message);
+};
 
-  /**
-   * `Option` does not have a value, and is a mandatory option.
-   *
-   * @param {Option} option
-   * @api private
-   */
+/**
+ * Variadic argument with `name` is not the last argument as required.
+ *
+ * @param {String} name
+ * @api private
+ */
 
-  missingMandatoryOptionValue(option) {
-    const message = `error: required option '${option.flags}' not specified`;
-    this._displayError(1, 'commander.missingMandatoryOptionValue', message);
-  };
+Command.prototype.variadicArgNotLast = function(name) {
+  const message = `error: variadic arguments must be last '${name}'`;
+  console.error(message);
+  this._exit(1, 'commander.variadicArgNotLast', message);
+};
 
-  /**
-   * Unknown option `flag`.
-   *
-   * @param {string} flag
-   * @api private
-   */
+/**
+ * Set the program version to `str`.
+ *
+ * This method auto-registers the "-V, --version" flag
+ * which will print the version number when passed.
+ *
+ * You can optionally supply the  flags and description to override the defaults.
+ *
+ * @param {String} str
+ * @param {String} [flags]
+ * @param {String} [description]
+ * @return {Command} for chaining
+ * @api public
+ */
 
-  unknownOption(flag) {
-    if (this._allowUnknownOption) return;
-    const message = `error: unknown option '${flag}'`;
-    this._displayError(1, 'commander.unknownOption', message);
-  };
+Command.prototype.version = function(str, flags, description) {
+  if (arguments.length === 0) return this._version;
+  this._version = str;
+  flags = flags || '-V, --version';
+  description = description || 'output the version number';
+  var versionOption = new Option(flags, description);
+  this._versionOptionName = versionOption.long.substr(2) || 'version';
+  this.options.push(versionOption);
+  var self = this;
+  this.on('option:' + this._versionOptionName, function() {
+    process.stdout.write(str + '\n');
+    self._exit(0, 'commander.version', str);
+  });
+  return this;
+};
 
-  /**
-   * Excess arguments, more than expected.
-   *
-   * @param {string[]} receivedArgs
-   * @api private
-   */
+/**
+ * Set the description to `str`.
+ *
+ * @param {String} str
+ * @param {Object} [argsDescription]
+ * @return {String|Command}
+ * @api public
+ */
 
-  _excessArguments(receivedArgs) {
-    if (this._allowExcessArguments) return;
+Command.prototype.description = function(str, argsDescription) {
+  if (arguments.length === 0) return this._description;
+  this._description = str;
+  this._argsDescription = argsDescription;
+  return this;
+};
 
-    const expected = this._args.length;
-    const s = (expected === 1) ? '' : 's';
-    const forSubcommand = this.parent ? ` for '${this.name()}'` : '';
-    const message = `error: too many arguments${forSubcommand}. Expected ${expected} argument${s} but got ${receivedArgs.length}.`;
-    this._displayError(1, 'commander.excessArguments', message);
-  };
+/**
+ * Set an alias for the command
+ *
+ * @param {String} alias
+ * @return {String|Command}
+ * @api public
+ */
 
-  /**
-   * Unknown command.
-   *
-   * @api private
-   */
+Command.prototype.alias = function(alias) {
+  var command = this;
+  if (this.commands.length !== 0) {
+    command = this.commands[this.commands.length - 1];
+  }
 
-  unknownCommand() {
-    const partCommands = [this.name()];
-    for (let parentCmd = this.parent; parentCmd; parentCmd = parentCmd.parent) {
-      partCommands.unshift(parentCmd.name());
-    }
-    const fullCommand = partCommands.join(' ');
-    const message = `error: unknown command '${this.args[0]}'.` +
-      (this._hasHelpOption ? ` See '${fullCommand} ${this._helpLongFlag}'.` : '');
-    this._displayError(1, 'commander.unknownCommand', message);
-  };
+  if (arguments.length === 0) return command._alias;
 
-  /**
-   * Set the program version to `str`.
-   *
-   * This method auto-registers the "-V, --version" flag
-   * which will print the version number when passed.
-   *
-   * You can optionally supply the  flags and description to override the defaults.
-   *
-   * @param {string} str
-   * @param {string} [flags]
-   * @param {string} [description]
-   * @return {this | string} `this` command for chaining, or version string if no arguments
-   */
+  if (alias === command._name) throw new Error('Command alias can\'t be the same as its name');
 
-  version(str, flags, description) {
-    if (str === undefined) return this._version;
-    this._version = str;
-    flags = flags || '-V, --version';
-    description = description || 'output the version number';
-    const versionOption = this.createOption(flags, description);
-    this._versionOptionName = versionOption.attributeName();
-    this.options.push(versionOption);
-    this.on('option:' + versionOption.name(), () => {
-      this._outputConfiguration.writeOut(`${str}\n`);
-      this._exit(0, 'commander.version', str);
-    });
-    return this;
-  };
+  command._alias = alias;
+  return this;
+};
 
-  /**
-   * Set the description to `str`.
-   *
-   * @param {string} [str]
-   * @param {Object} [argsDescription]
-   * @return {string|Command}
-   */
-  description(str, argsDescription) {
-    if (str === undefined && argsDescription === undefined) return this._description;
-    this._description = str;
-    this._argsDescription = argsDescription;
-    return this;
-  };
+/**
+ * Set / get the command usage `str`.
+ *
+ * @param {String} [str]
+ * @return {String|Command}
+ * @api public
+ */
 
-  /**
-   * Set an alias for the command.
-   *
-   * You may call more than once to add multiple aliases. Only the first alias is shown in the auto-generated help.
-   *
-   * @param {string} [alias]
-   * @return {string|Command}
-   */
+Command.prototype.usage = function(str) {
+  var args = this._args.map(function(arg) {
+    return humanReadableArgName(arg);
+  });
 
-  alias(alias) {
-    if (alias === undefined) return this._aliases[0]; // just return first, for backwards compatibility
+  var usage = '[options]' +
+    (this.commands.length ? ' [command]' : '') +
+    (this._args.length ? ' ' + args.join(' ') : '');
 
-    let command = this;
-    if (this.commands.length !== 0 && this.commands[this.commands.length - 1]._executableHandler) {
-      // assume adding alias for last added executable subcommand, rather than this
-      command = this.commands[this.commands.length - 1];
-    }
+  if (arguments.length === 0) return this._usage || usage;
+  this._usage = str;
 
-    if (alias === command._name) throw new Error('Command alias can\'t be the same as its name');
+  return this;
+};
 
-    command._aliases.push(alias);
-    return this;
-  };
+/**
+ * Get or set the name of the command
+ *
+ * @param {String} [str]
+ * @return {String|Command}
+ * @api public
+ */
 
-  /**
-   * Set aliases for the command.
-   *
-   * Only the first alias is shown in the auto-generated help.
-   *
-   * @param {string[]} [aliases]
-   * @return {string[]|Command}
-   */
+Command.prototype.name = function(str) {
+  if (arguments.length === 0) return this._name;
+  this._name = str;
+  return this;
+};
 
-  aliases(aliases) {
-    // Getter for the array of aliases is the main reason for having aliases() in addition to alias().
-    if (aliases === undefined) return this._aliases;
+/**
+ * Return prepared commands.
+ *
+ * @return {Array}
+ * @api private
+ */
 
-    aliases.forEach((alias) => this.alias(alias));
-    return this;
-  };
+Command.prototype.prepareCommands = function() {
+  return this.commands.filter(function(cmd) {
+    return !cmd._noHelp;
+  }).map(function(cmd) {
+    var args = cmd._args.map(function(arg) {
+      return humanReadableArgName(arg);
+    }).join(' ');
+
+    return [
+      cmd._name +
+        (cmd._alias ? '|' + cmd._alias : '') +
+        (cmd.options.length ? ' [options]' : '') +
+        (args ? ' ' + args : ''),
+      cmd._description
+    ];
+  });
+};
 
-  /**
-   * Set / get the command usage `str`.
-   *
-   * @param {string} [str]
-   * @return {String|Command}
-   */
+/**
+ * Return the largest command length.
+ *
+ * @return {Number}
+ * @api private
+ */
 
-  usage(str) {
-    if (str === undefined) {
-      if (this._usage) return this._usage;
+Command.prototype.largestCommandLength = function() {
+  var commands = this.prepareCommands();
+  return commands.reduce(function(max, command) {
+    return Math.max(max, command[0].length);
+  }, 0);
+};
 
-      const args = this._args.map((arg) => {
-        return humanReadableArgName(arg);
-      });
-      return [].concat(
-        (this.options.length || this._hasHelpOption ? '[options]' : []),
-        (this.commands.length ? '[command]' : []),
-        (this._args.length ? args : [])
-      ).join(' ');
-    }
+/**
+ * Return the largest option length.
+ *
+ * @return {Number}
+ * @api private
+ */
 
-    this._usage = str;
-    return this;
-  };
+Command.prototype.largestOptionLength = function() {
+  var options = [].slice.call(this.options);
+  options.push({
+    flags: this._helpFlags
+  });
 
-  /**
-   * Get or set the name of the command
-   *
-   * @param {string} [str]
-   * @return {string|Command}
-   */
+  return options.reduce(function(max, option) {
+    return Math.max(max, option.flags.length);
+  }, 0);
+};
 
-  name(str) {
-    if (str === undefined) return this._name;
-    this._name = str;
-    return this;
-  };
+/**
+ * Return the largest arg length.
+ *
+ * @return {Number}
+ * @api private
+ */
 
-  /**
-   * Return program help documentation.
-   *
-   * @param {{ error: boolean }} [contextOptions] - pass {error:true} to wrap for stderr instead of stdout
-   * @return {string}
-   */
+Command.prototype.largestArgLength = function() {
+  return this._args.reduce(function(max, arg) {
+    return Math.max(max, arg.name.length);
+  }, 0);
+};
 
-  helpInformation(contextOptions) {
-    const helper = this.createHelp();
-    if (helper.helpWidth === undefined) {
-      helper.helpWidth = (contextOptions && contextOptions.error) ? this._outputConfiguration.getErrHelpWidth() : this._outputConfiguration.getOutHelpWidth();
-    }
-    return helper.formatHelp(this, helper);
-  };
+/**
+ * Return the pad width.
+ *
+ * @return {Number}
+ * @api private
+ */
 
-  /**
-   * @api private
-   */
+Command.prototype.padWidth = function() {
+  var width = this.largestOptionLength();
+  if (this._argsDescription && this._args.length) {
+    if (this.largestArgLength() > width) {
+      width = this.largestArgLength();
+    }
+  }
 
-  _getHelpContext(contextOptions) {
-    contextOptions = contextOptions || {};
-    const context = { error: !!contextOptions.error };
-    let write;
-    if (context.error) {
-      write = (arg) => this._outputConfiguration.writeErr(arg);
-    } else {
-      write = (arg) => this._outputConfiguration.writeOut(arg);
+  if (this.commands && this.commands.length) {
+    if (this.largestCommandLength() > width) {
+      width = this.largestCommandLength();
     }
-    context.write = contextOptions.write || write;
-    context.command = this;
-    return context;
   }
 
-  /**
-   * Output help information for this command.
-   *
-   * Outputs built-in help, and custom text added using `.addHelpText()`.
-   *
-   * @param {{ error: boolean } | Function} [contextOptions] - pass {error:true} to write to stderr instead of stdout
-   */
+  return width;
+};
 
-  outputHelp(contextOptions) {
-    let deprecatedCallback;
-    if (typeof contextOptions === 'function') {
-      deprecatedCallback = contextOptions;
-      contextOptions = undefined;
-    }
-    const context = this._getHelpContext(contextOptions);
+/**
+ * Return help for options.
+ *
+ * @return {String}
+ * @api private
+ */
 
-    const groupListeners = [];
-    let command = this;
-    while (command) {
-      groupListeners.push(command); // ordered from current command to root
-      command = command.parent;
-    }
+Command.prototype.optionHelp = function() {
+  var width = this.padWidth();
 
-    groupListeners.slice().reverse().forEach(command => command.emit('beforeAllHelp', context));
-    this.emit('beforeHelp', context);
+  var columns = process.stdout.columns || 80;
+  var descriptionWidth = columns - width - 4;
 
-    let helpInformation = this.helpInformation(context);
-    if (deprecatedCallback) {
-      helpInformation = deprecatedCallback(helpInformation);
-      if (typeof helpInformation !== 'string' && !Buffer.isBuffer(helpInformation)) {
-        throw new Error('outputHelp callback must return a string or a Buffer');
-      }
-    }
-    context.write(helpInformation);
+  // Append the help information
+  return this.options.map(function(option) {
+    const fullDesc = option.description +
+      ((!option.negate && option.defaultValue !== undefined) ? ' (default: ' + JSON.stringify(option.defaultValue) + ')' : '');
+    return pad(option.flags, width) + '  ' + optionalWrap(fullDesc, descriptionWidth, width + 2);
+  }).concat([pad(this._helpFlags, width) + '  ' + optionalWrap(this._helpDescription, descriptionWidth, width + 2)])
+    .join('\n');
+};
 
-    this.emit(this._helpLongFlag); // deprecated
-    this.emit('afterHelp', context);
-    groupListeners.forEach(command => command.emit('afterAllHelp', context));
-  };
+/**
+ * Return command help documentation.
+ *
+ * @return {String}
+ * @api private
+ */
 
-  /**
-   * You can pass in flags and a description to override the help
-   * flags and help description for your command. Pass in false to
-   * disable the built-in help option.
-   *
-   * @param {string | boolean} [flags]
-   * @param {string} [description]
-   * @return {Command} `this` command for chaining
-   */
+Command.prototype.commandHelp = function() {
+  if (!this.commands.length) return '';
 
-  helpOption(flags, description) {
-    if (typeof flags === 'boolean') {
-      this._hasHelpOption = flags;
-      return this;
-    }
-    this._helpFlags = flags || this._helpFlags;
-    this._helpDescription = description || this._helpDescription;
+  var commands = this.prepareCommands();
+  var width = this.padWidth();
 
-    const helpFlags = _parseOptionFlags(this._helpFlags);
-    this._helpShortFlag = helpFlags.shortFlag;
-    this._helpLongFlag = helpFlags.longFlag;
+  var columns = process.stdout.columns || 80;
+  var descriptionWidth = columns - width - 4;
 
-    return this;
-  };
+  return [
+    'Commands:',
+    commands.map(function(cmd) {
+      var desc = cmd[1] ? '  ' + cmd[1] : '';
+      return (desc ? pad(cmd[0], width) : cmd[0]) + optionalWrap(desc, descriptionWidth, width + 2);
+    }).join('\n').replace(/^/gm, '  '),
+    ''
+  ].join('\n');
+};
 
-  /**
-   * Output help information and exit.
-   *
-   * Outputs built-in help, and custom text added using `.addHelpText()`.
-   *
-   * @param {{ error: boolean }} [contextOptions] - pass {error:true} to write to stderr instead of stdout
-   */
+/**
+ * Return program help documentation.
+ *
+ * @return {String}
+ * @api private
+ */
 
-  help(contextOptions) {
-    this.outputHelp(contextOptions);
-    let exitCode = process.exitCode || 0;
-    if (exitCode === 0 && contextOptions && typeof contextOptions !== 'function' && contextOptions.error) {
-      exitCode = 1;
+Command.prototype.helpInformation = function() {
+  var desc = [];
+  if (this._description) {
+    desc = [
+      this._description,
+      ''
+    ];
+
+    var argsDescription = this._argsDescription;
+    if (argsDescription && this._args.length) {
+      var width = this.padWidth();
+      var columns = process.stdout.columns || 80;
+      var descriptionWidth = columns - width - 5;
+      desc.push('Arguments:');
+      desc.push('');
+      this._args.forEach(function(arg) {
+        desc.push('  ' + pad(arg.name, width) + '  ' + wrap(argsDescription[arg.name], descriptionWidth, width + 4));
+      });
+      desc.push('');
     }
-    // message: do not have all displayed text available so only passing placeholder.
-    this._exit(exitCode, 'commander.help', '(outputHelp)');
-  };
+  }
 
-  /**
-   * Add additional text to be displayed with the built-in help.
-   *
-   * Position is 'before' or 'after' to affect just this command,
-   * and 'beforeAll' or 'afterAll' to affect this command and all its subcommands.
-   *
-   * @param {string} position - before or after built-in help
-   * @param {string | Function} text - string to add, or a function returning a string
-   * @return {Command} `this` command for chaining
-   */
-  addHelpText(position, text) {
-    const allowedValues = ['beforeAll', 'before', 'after', 'afterAll'];
-    if (!allowedValues.includes(position)) {
-      throw new Error(`Unexpected value for position to addHelpText.
-Expecting one of '${allowedValues.join("', '")}'`);
-    }
-    const helpEvent = `${position}Help`;
-    this.on(helpEvent, (context) => {
-      let helpStr;
-      if (typeof text === 'function') {
-        helpStr = text({ error: context.error, command: context.command });
-      } else {
-        helpStr = text;
-      }
-      // Ignore falsy value when nothing to output.
-      if (helpStr) {
-        context.write(`${helpStr}\n`);
-      }
-    });
-    return this;
+  var cmdName = this._name;
+  if (this._alias) {
+    cmdName = cmdName + '|' + this._alias;
+  }
+  var parentCmdNames = '';
+  for (var parentCmd = this.parent; parentCmd; parentCmd = parentCmd.parent) {
+    parentCmdNames = parentCmd.name() + ' ' + parentCmdNames;
   }
+  var usage = [
+    'Usage: ' + parentCmdNames + cmdName + ' ' + this.usage(),
+    ''
+  ];
+
+  var cmds = [];
+  var commandHelp = this.commandHelp();
+  if (commandHelp) cmds = [commandHelp];
+
+  var options = [
+    'Options:',
+    '' + this.optionHelp().replace(/^/gm, '  '),
+    ''
+  ];
+
+  return usage
+    .concat(desc)
+    .concat(options)
+    .concat(cmds)
+    .join('\n');
 };
 
 /**
- * Expose the root command.
+ * Output help information for this command.
+ *
+ * When listener(s) are available for the helpLongFlag
+ * those callbacks are invoked.
+ *
+ * @api public
  */
 
-exports = module.exports = new Command();
-exports.program = exports; // More explicit access to global command.
+Command.prototype.outputHelp = function(cb) {
+  if (!cb) {
+    cb = function(passthru) {
+      return passthru;
+    };
+  }
+  const cbOutput = cb(this.helpInformation());
+  if (typeof cbOutput !== 'string' && !Buffer.isBuffer(cbOutput)) {
+    throw new Error('outputHelp callback must return a string or a Buffer');
+  }
+  process.stdout.write(cbOutput);
+  this.emit(this._helpLongFlag);
+};
 
 /**
- * Expose classes
+ * You can pass in flags and a description to override the help
+ * flags and help description for your command.
+ *
+ * @param {String} [flags]
+ * @param {String} [description]
+ * @return {Command}
+ * @api public
  */
 
-exports.Command = Command;
-exports.Option = Option;
-exports.CommanderError = CommanderError;
-exports.InvalidOptionArgumentError = InvalidOptionArgumentError;
-exports.Help = Help;
+Command.prototype.helpOption = function(flags, description) {
+  this._helpFlags = flags || this._helpFlags;
+  this._helpDescription = description || this._helpDescription;
+
+  var splitFlags = this._helpFlags.split(/[ ,|]+/);
+
+  if (splitFlags.length > 1) this._helpShortFlag = splitFlags.shift();
+
+  this._helpLongFlag = splitFlags.shift();
+
+  return this;
+};
+
+/**
+ * Output help information and exit.
+ *
+ * @param {Function} [cb]
+ * @api public
+ */
+
+Command.prototype.help = function(cb) {
+  this.outputHelp(cb);
+  // exitCode: preserving original behaviour which was calling process.exit()
+  // message: do not have all displayed text available so only passing placeholder.
+  this._exit(process.exitCode || 0, 'commander.help', '(outputHelp)');
+};
 
 /**
  * Camel-case the given `flag`
  *
- * @param {string} flag
- * @return {string}
+ * @param {String} flag
+ * @return {String}
  * @api private
  */
 
 function camelcase(flag) {
-  return flag.split('-').reduce((str, word) => {
+  return flag.split('-').reduce(function(str, word) {
     return str + word[0].toUpperCase() + word.slice(1);
   });
 }
 
 /**
+ * Pad `str` to `width`.
+ *
+ * @param {String} str
+ * @param {Number} width
+ * @return {String}
+ * @api private
+ */
+
+function pad(str, width) {
+  var len = Math.max(0, width - str.length);
+  return str + Array(len + 1).join(' ');
+}
+
+/**
+ * Wraps the given string with line breaks at the specified width while breaking
+ * words and indenting every but the first line on the left.
+ *
+ * @param {String} str
+ * @param {Number} width
+ * @param {Number} indent
+ * @return {String}
+ * @api private
+ */
+function wrap(str, width, indent) {
+  var regex = new RegExp('.{1,' + (width - 1) + '}([\\s\u200B]|$)|[^\\s\u200B]+?([\\s\u200B]|$)', 'g');
+  var lines = str.match(regex) || [];
+  return lines.map(function(line, i) {
+    if (line.slice(-1) === '\n') {
+      line = line.slice(0, line.length - 1);
+    }
+    return ((i > 0 && indent) ? Array(indent + 1).join(' ') : '') + line.trimRight();
+  }).join('\n');
+}
+
+/**
+ * Optionally wrap the given str to a max width of width characters per line
+ * while indenting with indent spaces. Do not wrap if insufficient width or
+ * string is manually formatted.
+ *
+ * @param {String} str
+ * @param {Number} width
+ * @param {Number} indent
+ * @return {String}
+ * @api private
+ */
+function optionalWrap(str, width, indent) {
+  // Detect manually wrapped and indented strings by searching for line breaks
+  // followed by multiple spaces/tabs.
+  if (str.match(/[\n]\s+/)) return str;
+  // Do not wrap to narrow columns (or can end up with a word per line).
+  const minWidth = 40;
+  if (width < minWidth) return str;
+
+  return wrap(str, width, indent);
+}
+
+/**
  * Output help information if help flags specified
  *
  * @param {Command} cmd - command to output help for
- * @param {Array} args - array of options to search for help flags
+ * @param {Array} options - array of options to search for -h or --help
  * @api private
  */
 
-function outputHelpIfRequested(cmd, args) {
-  const helpOption = cmd._hasHelpOption && args.find(arg => arg === cmd._helpLongFlag || arg === cmd._helpShortFlag);
-  if (helpOption) {
-    cmd.outputHelp();
-    // (Do not have all displayed text available so only passing placeholder.)
-    cmd._exit(0, 'commander.helpDisplayed', '(outputHelp)');
+function outputHelpIfRequested(cmd, options) {
+  options = options || [];
+
+  for (var i = 0; i < options.length; i++) {
+    if (options[i] === cmd._helpLongFlag || options[i] === cmd._helpShortFlag) {
+      cmd.outputHelp();
+      // (Do not have all displayed text available so only passing placeholder.)
+      cmd._exit(0, 'commander.helpDisplayed', '(outputHelp)');
+    }
   }
 }
 
@@ -2135,38 +1578,27 @@ function outputHelpIfRequested(cmd, args) {
  * Takes an argument and returns its human readable equivalent for help usage.
  *
  * @param {Object} arg
- * @return {string}
+ * @return {String}
  * @api private
  */
 
 function humanReadableArgName(arg) {
-  const nameOutput = arg.name + (arg.variadic === true ? '...' : '');
+  var nameOutput = arg.name + (arg.variadic === true ? '...' : '');
 
   return arg.required
     ? '<' + nameOutput + '>'
     : '[' + nameOutput + ']';
 }
 
-/**
- * Parse the short and long flag out of something like '-m,--mixed <value>'
- *
- * @api private
- */
-
-function _parseOptionFlags(flags) {
-  let shortFlag;
-  let longFlag;
-  // Use original very loose parsing to maintain backwards compatibility for now,
-  // which allowed for example unintended `-sw, --short-word` [sic].
-  const flagParts = flags.split(/[ |,]+/);
-  if (flagParts.length > 1 && !/^[[<]/.test(flagParts[1])) shortFlag = flagParts.shift();
-  longFlag = flagParts.shift();
-  // Add support for lone short flag without significantly changing parsing!
-  if (!shortFlag && /^-[^-]$/.test(longFlag)) {
-    shortFlag = longFlag;
-    longFlag = undefined;
+// for versions before node v0.8 when there weren't `fs.existsSync`
+function exists(file) {
+  try {
+    if (fs.statSync(file).isFile()) {
+      return true;
+    }
+  } catch (e) {
+    return false;
   }
-  return { shortFlag, longFlag };
 }
 
 /**
@@ -2183,35 +1615,35 @@ function incrementNodeInspectorPort(args) {
   //  --inspect-brk[=[host:]port]
   //  --inspect-port=[host:]port
   return args.map((arg) => {
-    if (!arg.startsWith('--inspect')) {
-      return arg;
-    }
-    let debugOption;
-    let debugHost = '127.0.0.1';
-    let debugPort = '9229';
-    let match;
-    if ((match = arg.match(/^(--inspect(-brk)?)$/)) !== null) {
-      // e.g. --inspect
-      debugOption = match[1];
-    } else if ((match = arg.match(/^(--inspect(-brk|-port)?)=([^:]+)$/)) !== null) {
-      debugOption = match[1];
-      if (/^\d+$/.test(match[3])) {
-        // e.g. --inspect=1234
-        debugPort = match[3];
-      } else {
-        // e.g. --inspect=localhost
+    var result = arg;
+    if (arg.indexOf('--inspect') === 0) {
+      var debugOption;
+      var debugHost = '127.0.0.1';
+      var debugPort = '9229';
+      var match;
+      if ((match = arg.match(/^(--inspect(-brk)?)$/)) !== null) {
+        // e.g. --inspect
+        debugOption = match[1];
+      } else if ((match = arg.match(/^(--inspect(-brk|-port)?)=([^:]+)$/)) !== null) {
+        debugOption = match[1];
+        if (/^\d+$/.test(match[3])) {
+          // e.g. --inspect=1234
+          debugPort = match[3];
+        } else {
+          // e.g. --inspect=localhost
+          debugHost = match[3];
+        }
+      } else if ((match = arg.match(/^(--inspect(-brk|-port)?)=([^:]+):(\d+)$/)) !== null) {
+        // e.g. --inspect=localhost:1234
+        debugOption = match[1];
         debugHost = match[3];
+        debugPort = match[4];
       }
-    } else if ((match = arg.match(/^(--inspect(-brk|-port)?)=([^:]+):(\d+)$/)) !== null) {
-      // e.g. --inspect=localhost:1234
-      debugOption = match[1];
-      debugHost = match[3];
-      debugPort = match[4];
-    }
 
-    if (debugOption && debugPort !== '0') {
-      return `${debugOption}=${debugHost}:${parseInt(debugPort) + 1}`;
+      if (debugOption && debugPort !== '0') {
+        result = `${debugOption}=${debugHost}:${parseInt(debugPort) + 1}`;
+      }
     }
-    return arg;
+    return result;
   });
 }