getopt.net - A GNU and POSIX getopt port to .net

This repository contains the code for my port of the GNU getopt functionality found on most Unix-like systems.

getopt.net is written entirely in C# and is a "cleanroom port"; although not necessary it made the project that much more fun 😊

Installation

There are several methods of installing and using getopt.net in your project.

1. Add the repository as a submodule, checkout a tag and include it as a project reference in your solution
2. Use the NuGet package manager: install-package getopt.net-bsd Note the -bsd ending which shows the license used and not system requirements! getopt.net was already in use 😕
3. Use the dotnet command-line tools: dotnet add package getopt.net-bsd

NuGet page

Features

Full support for getopt-like command-line options

Separate options

• --help
  • -h
• --config=/path/to/config POSIX separator
  • --config /path/to/config GNU separator
  • -c /path/to/config POSIX separator
  • -c/path/to/config GNU extension

Compound options

• --console, -C
• --test, -t
• --config, -c
• -Ctc/path/to/config Options with required or optional arguments go last!

Support for options using the Windows convention

‍NOTE: It is possible to use the Windows argument separator (:) with all conventions.
To enable this, you must set AllowWindowsConventions to true.

Separate options

• /help
  • /h
• /config=/path/to/config POSIX separator
  • /config /path/to/config GNU separator
  • /config:/path/to/config Windows separator
  • /c /path/to/config POSIX separator
  • /c/path/to/config GNU extension

Compound options

• /console, /C
• /test, /t
• /config, /c
• /Ctc/path/to/config Options with required or optional arguments go last!

Support for Powershell-style options

Separate options

• -help
  • -h
• -config=/path/to/config POSIX separator
  • -config /path/to/config GNU separator
  • -config:/path/to/config Windows separator
  • -c /path/to/config POSIX separator
  • -c/path/to/config GNU extension

Compound options

• -console, -C
• -test, -t
• -config, -c
• -Ctc/path/to/config Options with required or optional arguments go last!

Support for paramfiles

Some applications, such as GCC, allow passing of paramfile arguments. A paramfile is a line-separated text file which contains one option (and argument) per line. Each line of the paramfile is parsed as if it were passed to getopt.net directly.

Syntax:

myapp @/path/to/paramfile

The standard getopt shortopt-string format is supported:

: denotes a required argument!

; denotes an optional argument!

If none of the above is present after a character in ShortOpts, then no argument is required.

getopt.ShortOpts = "abC:dE:f:GhIjkLmnop:q:r;";

POSIXly correct behaviour

If getopt.ShortOpts is prefixed by a +, or the environment variable POSIXLY_CORRECT is set, then getopt.net will stop processing more options as soon when the first non-option string is found.

If getopt.ShortOpts is prefixed by a -, then each non-option string will be treated as if it were the argument to an option with the value 1.

Customisation is available with long opts:

getopt.Options = new[] {
    new Option { Name = "help", ArgumentType = ArgumentType.None, Value = 'h' }, // brace-initialiser
    new Option("config", ArgumentType.Required, 'c'), // standard constructor
    new Option("version", ArgumentType.Optional, 'v')
};

Fallback to long opts (if available!)

Most developers will have experienced this at some point when using getopt; you added an option to your long opts, but forgot it in your shortopt string. getopt.net improves this behaviour and will check the Options array to see if the option you've provided is there.

Customisable behaviour

getopt.net can be configured to not throw exceptions if that's your thing. Just set the IgnoreXXX options to true, and getopt.net will ignore bad user input!

If IgnoreInvalidOptions is enabled, entering an unknown option won't throw an exception, but instead a ! will be returned. If IgnoreMissingArguments is enabled, forgetting to add a required argument won't thow an exception either! Instead, ? will be returned.

The exceptions do contain more info, however.

Help text generation

getopt.net can generate a help text for you, by simply calling getopt.GenerateHelpText().

The behaviour of the help text generator can be customised to suit your needs. By default, getopt.net will not output application name, version or copyright information. This must be provided with the HelpTextConfig object.

If no application name is provided, getopt.net will attempt to read the application name from the Assembly.
Should this fail, getopt.net will identify your program as unknown.

The default configuration outputs options and switches using the GNU/POSIX convention and doesn't print the conventions supported by your application.

Here's an example:

var getopt = new GetOpt {
    AppArgs = args,
    Options = new[] {
        new Option("help",      ArgumentType.None,      'h', "Displays this help text."),
        new Option("version",   ArgumentType.None,      'v', "Displays the version of this program."),
        new Option("file",      ArgumentType.Required,  'f', "Reads the file back to stdout. The file is read into a local buffer and then printed out. Also I created this really long description to show that getopt.net can handle long descriptions."),
    },
    ShortOpts = "hvf:t;", // the last option isn't an error!
    AllowParamFiles = true,
    AllowWindowsConventions = true,
    AllowPowershellConventions = true
};
 
static void PrintHelp(GetOpt getopt) {
    Console.WriteLine(getopt.GenerateHelpText(new HelpTextConfig {
        ApplicationName = "getopt.net reference",
        ApplicationVersion = "v1.0.0",
        FooterText = "This is a reference implementation of getopt.net in C#.",
        OptionConvention = OptionConvention.GnuPosix, // Change me to different conventions
        ShowSupportedConventions = true // I'm false by default, but enabling me shows which conventions your app supports
    }));
}

produces the following output:

getopt.net reference v1.0.0 © 2023 Simon Cahill (contact@simonc.eu)
 
Usage:
    getopt.net reference [options]
 
Supported option conventions:
    Windows (/): yes
    Powershell (-): yes
    Gnu/Posix (-, --): yes
 
Switches:
    -h, --help    Displays this help text.
    -v, --version Displays the version of this program.
 
Options:
                  Reads the file back to stdout. The file is read into a local buffer and then
                  printed out. Also I created this really long description to show that getopt.net
    -f, --file    can handle long descriptions.
 
This is a reference implementation of getopt.net in C#.

Usage:

For a more detailled description of using getopt.net, please consult the Wiki.

Basic usage in C♯

using getopt.net;
 
static void Main(string[] args) {
 
    var getopt = new Getopt {
        Options = new[] {
            new Option("help",    ArgumentType.None, 'h'),
            new Option("version", ArgumentType.None, 'v'),
            // or, alternatively
            new Option { Name = "config", ArgumentType.Required, 'c' }
        },
        ShortOpts = "hvc:",
        AppArgs = args, // REQUIRED
        OnlyShortOpts = false,
        // AllowWindowsConventions = true, // enable this for Windows-style options
        // other options here
    };
 
    int opt = 0;
    // GetNextOpt may throw exceptions, depending on your settings!
    while ((opt = getopt.GetNextOpt(out var optArg)) != -1) {
        switch (opt) {
            case 'h':
                // print help or something
                break;
            case 'c':
                // do something with optArg
                break;
        }
    }
}

Basic usage in VB.Net

Imports getopt.net
 
module Program
 
    Dim _progOptions() As [Option] = {
        New [Option]("help", ArgumentType.None, "h"c),
        New [Option]("version", ArgumentType.None, "v"c),
        New [Option]("file", ArgumentType.Required, "f"c)
    }
 
    Dim _progShortOptions As String = "hvf:"
 
    sub Main(args as string())
        Dim getopt = New GetOpt With {
            .AppArgs = args,
            .Options = _progOptions,
            .ShortOpts = _progShortOptions,
            ' .AllowWindowsConventions = true ' enable me for Windows-style options!
        }
 
        Dim optChar = 0
        Dim optArg As String = Nothing
        Dim fileToRead As String = Nothing
 
        While optChar <> -1
            optChar = getopt.GetNextOpt(optArg)
 
            Select Case optChar
                Case Convert.ToInt32("h"c)
                    ' do something
                    Return
                Case Convert.ToInt32("v"c)
                    ' do something else
                    Return
                Case Convert.ToInt32("f"c)
                    ' do something with optArg
            End Select
        End While
    end sub
 
end module

Bugs and errors

If you encounter a bug, please add a GitHub Issue and/or create a fork of the project and create a pull request.