help subcommand

[coolaj86]

I'd be be just as happy if the first version of the help did nothing more than print the URL to this repo's README, however, it shouldn't fail.

Personally, I often sidestep the flag parser and have POSIX, BSD, and Go-style for help and version, like this:

	if len(os.Args) > 1 {
		// `version`, `-version`, `--version`, `-V`
		if ("version" == strings.TrimLeft(os.Args[1], "-") || "-V" == os.Args[1]) {
			printVersion()
			os.Exit(0)
			return
		}
	}

	if len(os.Args) > 1 {
		// `help`, `-help`, `--help`,
		if ("help" == strings.TrimLeft(os.Args[1], "-")) {
			printHelp()
			os.Exit(0)
			return
		}
	}

That way it meets everyone's expectations and costs nothing in complexity (though sometimes help may need to come after some sort of flag package has parsed all the things... or just `long string` it.

[mohammed90]

Actually I'm considering using Cobra. That requires extensive effort to retrofit.

[coolaj86]

That seems way overkill. This has two subcommands and two flags. Why bring in those deps when the standard library will do?

[francislavoie]

Cobra would let us generate man pages and whatnot which help with packaging. It's also a nicer API to write against. It's a slim dependency now (compared to a couple years ago which necessitated https://github.com/spf13/viper) so IMO no harm bringing it in to make UX easier and more consistent in addition to the extra features it provides.

[millette]

See also #174