如何使用眼镜蛇在Go CLI中制作所需的子命令

I am using Cobra to make some cli updated to my app. I want to make this command required, meaning the application should fail if it doesn't find the argument it is looking for.

package commands

import (
    "github.com/spf13/cobra"
    "errors"
    "fmt"
)

var (
    Env string
)

var RootCmd = &cobra.Command{
    Use:   "myapp",
    Short: "tool",
    Long:  `tool`,
    Run: func(cmd *cobra.Command, args []string)  {
        // Root command does nothing
    },
}

func init() {
    RootCmd.AddCommand(Environment)
}

var Environment = &cobra.Command{
    Use:   "env",
    Short: "Specify Environment to run against",
    Long: `Can be dev or prod`,
    Args: func(cmd *cobra.Command, args []string) error {
        if len(args) != 1 {
            return errors.New("requires at least one arg")
        }

        if args[0] == "dev" || args[0] == "prod" {
            return nil
        }else {
            return errors.New("input can only be dev or prod")
        }
        return fmt.Errorf("invalid env specified: %s", args[0])
    },
    PreRunE: func(cmd *cobra.Command, args []string) error {
        if len(args) != 1 {
          return fmt.Errorf("env is required")
        }
      return nil
    },
    Run: func(cmd *cobra.Command, args []string) {
        Env = args[0]
    },
}

and main package is

package main

import (
    "fmt"
    "log"
    "os"
    "util"
    "commands"
)

func main() {
    log.Println("Executing")

    if err := commands.RootCmd.Execute(); err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
    log.Println("Executing")
}

Now if I run this as ./myApp without any env, it doesn't complain about it. However if I use env after myapp then it activates the function and runs all the validations.

You can just make the body of the function handle it, perhaps by printing help and exiting as non-successful:

Run: func(cmd *cobra.Command, args []string)  {
    // Root command does nothing
    cmd.Help()
    os.Exit(1)
},