cobra command

Posted by 胡伟煌 on 2020-09-16

本文以cobra-demo为例介绍cobra添加命令的具体使用操作。

0. cobra-demo

cobra-demo编译二进制执行的结果如下。具体代码参考:https://github.com/huweihuang/cobra-demo

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 $ ./cobra-demo 
A longer description that spans multiple lines and likely contains
examples and usage of using your application. For example:

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.

Usage:
cobra-demo [command]

Available Commands:
config A brief description of your command
help Help about any command
server A brief description of your command

Flags:
--config string config file (default is $HOME/.cobra-demo.yaml)
-h, --help help for cobra-demo
-t, --toggle Help message for toggle

Use "cobra-demo [command] --help" for more information about a command.

1. cobra init

cobra init 的具体使用参考 init

1.1. cobra init --pkg-name

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cobra init <cobra-demo> --pkg-name github.com/huweihuang/cobra-demo -a 'author name <email>'

执行以上命令,创建的文件目录结构如下:

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./
├── LICENSE
├── cmd
│   ├── root.go
└── main.go

1.2. main.go

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package main

import "github.com/huweihuang/cobra-demo/cmd"

func main() {
cmd.Execute()
}

1.3. cmd/root.go

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package cmd

import (
"fmt"
"os"
"github.com/spf13/cobra"

homedir "github.com/mitchellh/go-homedir"
"github.com/spf13/viper"

)


var cfgFile string


// rootCmd represents the base command when called without any subcommands
var rootCmd = &cobra.Command{
Use: "cobra-demo",
Short: "A brief description of your application",
Long: `A longer description that spans multiple lines and likely contains
examples and usage of using your application. For example:

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.`,
// Uncomment the following line if your bare application
// has an action associated with it:
// Run: func(cmd *cobra.Command, args []string) { },
}

// Execute adds all child commands to the root command and sets flags appropriately.
// This is called by main.main(). It only needs to happen once to the rootCmd.
func Execute() {
if err := rootCmd.Execute(); err != nil {
fmt.Println(err)
os.Exit(1)
}
}

func init() {
cobra.OnInitialize(initConfig)

// Here you will define your flags and configuration settings.
// Cobra supports persistent flags, which, if defined here,
// will be global for your application.

rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.cobra-demo.yaml)")


// Cobra also supports local flags, which will only run
// when this action is called directly.
rootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
}


// initConfig reads in config file and ENV variables if set.
func initConfig() {
if cfgFile != "" {
// Use config file from the flag.
viper.SetConfigFile(cfgFile)
} else {
// Find home directory.
home, err := homedir.Dir()
if err != nil {
fmt.Println(err)
os.Exit(1)
}

// Search config in home directory with name ".cobra-demo" (without extension).
viper.AddConfigPath(home)
viper.SetConfigName(".cobra-demo")
}

viper.AutomaticEnv() // read in environment variables that match

// If a config file is found, read it in.
if err := viper.ReadInConfig(); err == nil {
fmt.Println("Using config file:", viper.ConfigFileUsed())
}
}

2. cobra add

cobra add 的具体使用参考 add

2.1. cobra add command

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cobra add serve -a 'author name <email>'
cobra add config -a 'author name <email>'
cobra add create -p 'configCmd' -a 'author name <email>'# 在父命令config命令下创建子命令create,若没有指定-p,默认的父命令为rootCmd。

执行以上命令,创建的文件目录结构如下:

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./
├── LICENSE
├── cmd
│   ├── config.go # rootCmd的子命令
│   ├── create.go # config的子命令
│   ├── root.go # 默认父命令
│   └── server.go # rootCmd的子命令
└── main.go

2.2. cmd/config.go

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package cmd

import (
"fmt"

"github.com/spf13/cobra"
)

// configCmd represents the config command
var configCmd = &cobra.Command{
Use: "config",
Short: "A brief description of your command",
Long: `A longer description that spans multiple lines and likely contains examples
and usage of using your command. For example:

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.`,
Run: func(cmd *cobra.Command, args []string) {
fmt.Println("config called")
},
}

func init() {
rootCmd.AddCommand(configCmd)

// Here you will define your flags and configuration settings.

// Cobra supports Persistent Flags which will work for this command
// and all subcommands, e.g.:
// configCmd.PersistentFlags().String("foo", "", "A help for foo")

// Cobra supports local flags which will only run when this command
// is called directly, e.g.:
// configCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
}

2.3. cmd/create.go

create为config的子命令。

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package cmd

import (
"fmt"

"github.com/spf13/cobra"
)

// createCmd represents the create command
var createCmd = &cobra.Command{
Use: "create",
Short: "A brief description of your command",
Long: `A longer description that spans multiple lines and likely contains examples
and usage of using your command. For example:

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.`,
Run: func(cmd *cobra.Command, args []string) {
fmt.Println("create called")
},
}

func init() {
configCmd.AddCommand(createCmd)

// Here you will define your flags and configuration settings.

// Cobra supports Persistent Flags which will work for this command
// and all subcommands, e.g.:
// createCmd.PersistentFlags().String("foo", "", "A help for foo")

// Cobra supports local flags which will only run when this command
// is called directly, e.g.:
// createCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
}

参考:



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