Kingpin

Kingpin is a fluent-style, type-safe command-line parser. It supports flags, nested commands, and positional arguments. Second to parsing, providing the user with useful help is probably the most important thing a command-line parser does. Kingpin tries to provide detailed contextual help if --help is encountered at any point in the command line (excluding after --). Flags can be specified at any point after their definition, not just immediately after their associated command. Kingpin can be used for simple flag+arg applications. Kingpin supports reading arguments from a file.