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Command Line Parser Library

Command Line Parser Library pre-release for CLR.

The Command Line Parser Library offers to CLR applications a clean and concise API for manipulating command line arguments and related tasks defining switches, options and verb commands. It allows you to display an help screen with an high degree of customization and a simple way to report syntax errors to the end user. Everything that is boring and repetitive to be programmed stands up on library shoulders, letting developers concentrate on core logic. This library provides hassle free command line parsing with a constantly updated API since 2005.


  • .NET Framework 3.5+
  • Mono 2.1+ Profile

Current Release:

  • This is a pre-release, for documentation please read appropriate wiki section.

At glance:

  • One line parsing using default singleton: CommandLine.Parser.Default.ParseArguments(...).
  • One line help screen generator: HelpText.AutoBuild(...).
  • Map command line arguments to sequences (IEnumerable<T>), enum or standard scalar types.
  • Plug-In friendly architecture as explained here.
  • Define verb commands as git commit -a.
  • Most of features applies with a CoC philosophy.
  • F# specific API (work in progress).

To install:

  • NuGet way (latest stable): Install-Package CommandLineParser
  • NuGet way (latest version): Install-Package CommandLineParser -pre
  • XCOPY way: cp -r CommandLine/src/libcmdline To/Your/Project/Dir

To build:

MonoDevelop or Visual Studio

Public API:

Latest changes are recorded from Version, please refer to this document.


The project is and well suited to be included in your application. If you don't merge it to your project tree, you must reference CommandLine.dll and import CommandLine and CommandLine.Text namespaces (or install via NuGet). The help text builder and its support types lives in CommandLine.Text namespace that is loosely coupled with the parser. However is good to know that HelpText class will avoid a lot of repetitive coding.

Define a class to receive parsed values:

class Options {
  [Option('r', "read", Required = true,
    HelpText = "Input files to be processed.")]
  public IEnumerable<string> InputFiles { get; set; }

  // omitting long name, default --verbose
  [Option(DefaultValue = true,
    HelpText = "Prints all messages to standard output.")]
  public bool Verbose { get; set; }

  public int Offset { get; set;}

Consume them:

static void Main(string[] args) {
  var result = CommandLine.Parser.Default.ParseArguments<Options>(args);
  if (!result.Errors.Any()) {
    // Values are available here
    if (result.Value.Verbose) Console.WriteLine("Filenames: {0}", string.Join(",", result.Value.InputFiles.ToArray()));


Thanks to JetBrains for providing an open source license for ReSharper.

Main Contributors (alphabetical order):

  • Alexander Fast (@mizipzor)
  • Dan Nemec (@nemec)
  • Kevin Moore (@gimmemoore)
  • Steven Evans

Resources for newcomers:

Latest Changes:

  • Implemented issue #31 (double dash), thanks also to PR #77 by Tom Glastonbury (@tg73).


Giacomo Stelluti Scala

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