clingon is a command-line option parsing library for Common Lisp. Its features include:

• Support for subcommands

• Support for command aliases

• Support for short and long options

• Related options may be grouped into categories

• Short options may be collapsed into a single argument, as in -xyz

• Long options support the notations --long-opt arg and --long-opt=arg

• Automatic generation of help/usage information for commands and subcommands

• Out-of-the-box support for --version and --help

• Support for various kinds of options including string, integer, boolean, switch, enum, list, counter, filepath, etc.

• Subcommands can look up global options defined in parent commands

• Support for required options

• Options can be initialized via environment variables

• Single interface for creating options using CLINGON:MAKE-OPTION

• Generate documentation for your command-line application

• Support for pre-hook and post-hook actions for commands, which allow invoking functions before and after the respective handler of the command is executed

• Support for Bash and Zsh completions

• Extensibility, so if you don't find something you need you can extend it by developing a new option kind, or even a new mechanism for initializing options, e.g., by looking up an external key/value store