cmdr 有助于在 Go 中使用子命令编写命令行程序。
例子.go：
package main
import (
"github.com/rsms/cmdr"
)
var quiet = false
var rootDir = "."
var version = cmdr . Cmd ( "version" , "Show version" , func () {
println ( "cmdr example v1.2.3" )
})
var foo = cmdr . Cmd ( "foo" , "Example command" , func ( opt * struct {
FooBar bool ` Bar the foo with some bar`
FirstName string `="John" Name of
