goland 调试器 delve

 Cobra is both a library for creating powerful modern CLI applications as well as a program to generate applications and command files. Cobra is used in many Go projects such as [Kubernetes](http://kubernetes.io/), [Hugo](https://gohugo.io), and [Github CLI](https://github.com/cli/cli) to name a few. [This list](./projects_using_cobra.md) contains a more extensive list of projects using Cobra. [](https://github.com/spf13/cobra/actions?query=workflow%3ATest) [](https://travis-ci.org/spf13/cobra) [](https://godoc.org/github.com/spf13/cobra) [](https://goreportcard.com/report/github.com/spf13/cobra) [](https://gophers.slack.com/archives/CD3LP1199) # Table of Contents - [Overview](#overview) - [Concepts](#concepts) * [Commands](#commands) * [Flags](#flags) - [Installing](#installing) - [Getting Started](#getting-started) * [Using the Cobra Generator](#using-the-cobra-generator) * [Using the Cobra Library](#using-the-cobra-library) * [Working with Flags](#working-with-flags) * [Positional and Custom Arguments](#positional-and-custom-arguments) * [Example](#example) * [Help Command](#help-command) * [Usage Message](#usage-message) * [PreRun and PostRun Hooks](#prerun-and-postrun-hooks) * [Suggestions when "unknown command" happens](#suggestions-when-unknown-command-happens) * [Generating documentation for your command](#generating-documentation-for-your-command) * [Generating shell completions](#generating-shell-completions) - [Contributing](CONTRIBUTING.md) - [License](#license) # Overview Cobra is a library providing a simple interface to create powerful modern CLI interfaces similar to git & go tools. Cobra is also an application that will generate your application scaffolding to rapidly develop a Cobra-based application. Cobra provides: * Easy subcommand-based CLIs: `app server`, `app fetch`, etc. * Fully POSIX-compliant flags (including short & long versions) * Nested subcommands * Global, local and cascading flags * Easy generation of applications & commands with `cobra init appname` & `cobra add cmdname` * Intelligent suggestions (`app srver`... did you mean `app server`?) * Automatic help generation for commands and flags * Automatic help flag recognition of `-h`, `--help`, etc. * Automatically generated shell autocomplete for your application (bash, zsh, fish, powershell) * Automatically generated man pages for your application * Command aliases so you can change things without breaking them * The flexibility to define your own help, usage, etc. * Optional tight integration with [viper](http://github.com/spf13/viper) for 12-factor apps # Concepts Cobra is built on a structure of commands, arguments & flags. **Commands** represent actions, **Args** are things and **Flags** are modifiers for those actions. The best applications read like sentences when used, and as a result, users intuitively know how to interact with them. The pattern to follow is `APPNAME VERB NOUN --ADJECTIVE.` or `APPNAME COMMAND ARG --FLAG` A few good real world examples may better illustrate this point. In the following example, 'server' is a command, and 'port' is a flag: hugo server --port=1313 In this command we are telling Git to clone the url bare. git clone URL --bare ## Commands Command is the central point of the application. Each interaction that the application supports will be contained in a Command. A command can have children commands and optionally run an action. In the example above, 'server' is the command. [More about cobra.Command](https://godoc.org/github.com/spf13/cobra#Command) ## Flags A flag is a way to modify the behavior of a command. Cobra supports fully POSIX-compliant flags as well as the Go [flag package](https://golang.org/pkg/flag/). A Cobra command can define flags that persist through to children commands and flags that are only available to that command. In the example above, 'port' is the flag. Flag functionality is provided by the [pflag library](https://github.com/spf13/pflag), a fork of the flag standard library which maintains the same interface while adding POSIX compliance. # Installing Using Cobra is easy. First, use `go get` to install the latest version of the library. This command will install the `cobra` generator executable along with the library and its dependencies: go get -u github.com/spf13/cobra Next, include Cobra in your application: ```go import "github.com/spf13/cobra" ``` # Getting Started While you are welcome to provide your own organization, typically a Cobra-based application will follow the following organizational structure: ``` ▾ appName/ ▾ cmd/ add.go your.go commands.go here.go main.go ``` In a Cobra app, typically the main.go file is very bare. It serves one purpose: initializing Cobra. ```go package main import ( "{pathToYourApp}/cmd" ) func main() { cmd.Execute() } ``` ## Using the Cobra Generator Cobra provides its own program that will create your application and add any commands you want. It's the easiest way to incorporate Cobra into your application. [Here](https://github.com/spf13/cobra/blob/master/cobra/README.md) you can find more information about it. ## Using the Cobra Library To manually implement Cobra you need to create a bare main.go file and a rootCmd file. You will optionally provide additional commands as you see fit. ### Create rootCmd Cobra doesn't require any special constructors. Simply create your commands. Ideally you place this in app/cmd/root.go: ```go var rootCmd = &cobra.Command{ Use: "hugo", Short: "Hugo is a very fast static site generator", Long: `A Fast and Flexible Static Site Generator built with love by spf13 and friends in Go. Complete documentation is available at http://hugo.spf13.com`, Run: func(cmd *cobra.Command, args []string) { // Do Stuff Here }, } func Execute() { if err := rootCmd.Execute(); err != nil { fmt.Fprintln(os.Stderr, err) os.Exit(1) } } ``` You will additionally define flags and handle configuration in your init() function. For example cmd/root.go: ```go package cmd import ( "fmt" "os" homedir "github.com/mitchellh/go-homedir" "github.com/spf13/cobra" "github.com/spf13/viper" ) var ( // Used for flags. cfgFile string userLicense string rootCmd = &cobra.Command{ Use: "cobra", Short: "A generator for Cobra based Applications", Long: `Cobra is a CLI library for Go that empowers applications. This application is a tool to generate the needed files to quickly create a Cobra application.`, } ) // Execute executes the root command. func Execute() error { return rootCmd.Execute() } func init() { cobra.OnInitialize(initConfig) rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.cobra.yaml)") rootCmd.PersistentFlags().StringP("author", "a", "YOUR NAME", "author name for copyright attribution") rootCmd.PersistentFlags().StringVarP(&userLicense, "license", "l", "", "name of license for the project") rootCmd.PersistentFlags().Bool("viper", true, "use Viper for configuration") viper.BindPFlag("author", rootCmd.PersistentFlags().Lookup("author")) viper.BindPFlag("useViper", rootCmd.PersistentFlags().Lookup("viper")) viper.SetDefault("author", "NAME HERE <EMAIL ADDRESS>") viper.SetDefault("license", "apache") rootCmd.AddCommand(addCmd) rootCmd.AddCommand(initCmd) } func initConfig() {