人工智能-项目实践-区块链-基于Fabric超级账本为底层的企业资产管理、交易、防伪、溯源一体化的开源区块链解决方案.zip

 Cobra is both a library for creating powerful modern CLI applications as well as a program to generate applications and command files. Many of the most widely used Go projects are built using Cobra including: * [Kubernetes](http://kubernetes.io/) * [Hugo](http://gohugo.io) * [rkt](https://github.com/coreos/rkt) * [etcd](https://github.com/coreos/etcd) * [Docker (distribution)](https://github.com/docker/distribution) * [OpenShift](https://www.openshift.com/) * [Delve](https://github.com/derekparker/delve) * [GopherJS](http://www.gopherjs.org/) * [CockroachDB](http://www.cockroachlabs.com/) * [Bleve](http://www.blevesearch.com/) * [ProjectAtomic (enterprise)](http://www.projectatomic.io/) * [Parse (CLI)](https://parse.com/) * [GiantSwarm's swarm](https://github.com/giantswarm/cli) * [Nanobox](https://github.com/nanobox-io/nanobox)/[Nanopack](https://github.com/nanopack) [](https://travis-ci.org/spf13/cobra) [](https://circleci.com/gh/spf13/cobra) [](https://godoc.org/github.com/spf13/cobra)  # 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 create appname` & `cobra add cmdname` * Intelligent suggestions (`app srver`... did you mean `app server`?) * Automatic help generation for commands and flags * Automatic detailed help for `app help [command]` * Automatic help flag recognition of `-h`, `--help`, etc. * Automatically generated bash autocomplete for your application * Automatically generated man pages for your application * Command aliases so you can change things without breaking them * The flexibilty to define your own help, usage, etc. * Optional tight integration with [viper](http://github.com/spf13/viper) for 12-factor apps Cobra has an exceptionally clean interface and simple design without needless constructors or initialization methods. Applications built with Cobra commands are designed to be as user-friendly as possible. Flags can be placed before or after the command (as long as a confusing space isn’t provided). Both short and long flags can be used. A command need not even be fully typed. Help is automatically generated and available for the application or for a specific command using either the help command or the `--help` flag. # 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 will read like sentences when used. Users will know how to use the application because they will natively understand how to use it. 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. A Command has the following structure: ```go type Command struct { Use string // The one-line usage message. Short string // The short description shown in the 'help' output. Long string // The long message shown in the 'help <this-command>' output. Run func(cmd *Command, args []string) // Run runs the 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/ogier/pflag), a fork of the flag standard library which maintains the same interface while adding POSIX compliance. ## Usage Cobra works by creating a set of commands and then organizing them into a tree. The tree defines the structure of the application. Once each command is defined with its corresponding flags, then the tree is assigned to the commander which is finally executed. # Installing Using Cobra is easy. First, use `go get` to install the latest version of the library. This command will install the `cobra` generator executible along with the library: > go get -v github.com/spf13/cobra/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, to initialize Cobra. ```go package main import "{pathToYourApp}/cmd" func main() { if err := cmd.RootCmd.Execute(); err != nil { fmt.Println(err) os.Exit(-1) } } ``` ## 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. In order to use the cobra command, compile it using the following command: > go install github.com/spf13/cobra/cobra This will create the cobra executable under your go path bin directory! ### cobra init The `cobra init [yourApp]` command will create your initial application code for you. It is a very powerful application that will populate your program with the right structure so you can immediately enjoy all the benefits of Cobra. It will also automatically apply the license you specify to your application. Cobra init is pretty smart. You can provide it a full path, or simply a path similar to what is expected in the import. ``` cobra init github.com/spf13/newAppName ``` ### cobra add Once an application is initialized Cobra can create additional commands for you. Let's say you created an app and you wanted the following commands for it: * app serve * app config * app config create In your project directory (where your main.go file is) you would run the following: ``` cobra add serve cobra add config cobra add create -p 'configCmd' ``` Once you have run these three commands you would have an app structure that would look like: ``` ▾ app/ ▾ cmd/ serve.go config.go create.go main.go ``` at this point you can run `go run main.go` and it would run your app. `go run main.go serve`, `go run main.go config`, `go run main.go config create` along with `go run main.go help serve`, etc would all work. Obviously you haven't added your own code to these yet, the commands are ready for you to give them their tasks. Have fun. ### Configuring the cobra generator The cobra generator will be easier to use if you provide a simple configuration file which will help you eliminate providing a