go-flags: a go library for parsing command line arguments

This library provides similar functionality to the builtin flag library of go, but provides much more functionality and nicer formatting.

A short list of supported features:

• Short names (-v)
• Long names (--verbose)
• Options with and without arguments (bool v.s. other type)
• Options with optional arguments and default values
• Multiple option groups each containing a set of options
• Easy specification of options using field structs
• Generate and print well-formatted help message
• Passing remaining command line arguments after -- (optional)
• Ignoring unknown command line options (optional)
• Supports -I/usr/include -I=/usr/include -I /usr/include option argument specification
• Multiple short options -aux
• Supports all primitive go types (string, int{8..64}, uint{8..64}, float)
• Same option multiple times (can store in slice or last option counts)
• Supports maps, slices and function callbacks

Example:

var opts struct {
	// Slice of bool will append 'true' each time the option
	// is encountered (can be set multiple times, like -vvv)
	Verbose []bool `short:"v" long:"verbose" description:"Show verbose debug information"`

	// Example of automatic marshalling to desired type (uint)
	Offset uint `long:"offset" description:"Offset"`

	// Example of a callback, called each time the option is found.
	Call func(string) `short:"c" description:"Call phone number"`
}

// Callback which will invoke callto:<argument> to call a number.
// Note that this works just on OS X (and probably only with
// Skype) but it shows the idea.
opts.Call = func(num string) {
	cmd := exec.Command("open", "callto:" + num)
	cmd.Start()
	cmd.Process.Release()
}

// Parse flags
args, err := flags.Parse(&opts)

if err != nil {
	os.Exit(1)
}

fmt.Printf("Verbosity: %d\n", len(opts.Verbose))
fmt.Printf("Offset: %d\n", opts.Offset)
fmt.Printf("Remaining args: %s\n", strings.Join(args, " "))

// Output: Verbosity: 0
// Offset: 0
// Remaining args:

More information can be found in the godocs: http://go.pkgdoc.org/github.com/jessevdk/go-flags