Go语言cobra库学习笔记——从入门到精通

在第一部分我们已经添加了show命令，现在我们修改show.go文件。
1）首先我们实现输出当前时间的功能。
下面是初始化的内容：

// showCmd represents the show command
var showCmd = &cobra.Command{
	Use:   "show",
	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("show called")
	},
}

// ShowTime 显示当前时间
func ShowTime(cmd *cobra.Command, args []string) {
	fmt.Println(time.Now())
}

然后将函数给Command.Run赋值：

// showCmd represents the show command
var showCmd = &cobra.Command{
	Use:   "show",
	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: ShowTime, // 这里改为函数名称
}

2）修改help命令。
help命令有两个，一个是short一个是lang，很明显short命令用来定义简短的说明，lang命令用来定义详细说明，下面我们修改show命令的help:

// showCmd represents the show command
var showCmd = &cobra.Command{
	Use:   "show",
	Short: "Displays the current time",
	Long: `You can use the time show command to view the current time. For example:

$ ./time show
2020-07-03 15:01:59.6035666 +0800 CST m=+0.013998501`,
	Run: ShowTime,
}

修改完成，我们编译代码：

$ go build -o time main.go

执行time命令，我们可以看到show命令后面的说明变成了我们定义的简短说明：

$ ./time
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:
  time [command]

Available Commands:
  help        Help about any command
  show        Displays the current time

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

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

我们再执行time show --help命令，可以看到现在展示了show命令的详细说明：

$ ./time show --help
You can use the time show command to view the current time. For example:

$ ./time show
2020-07-03 15:01:59.6035666 +0800 CST m=+0.013998501

Usage:
  time show [flags]

Flags:
  -h, --help   help for show

Global Flags:
      --config string   config file (default is $HOME/.time.yaml)