开发CLI工具

cli: https://github.com/urfave/cli/blob/master/docs/v2/manual.md

交互式: https://github.com/manifoldco/promptui

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app := &cli.App{
		Flags: []cli.Flag {
			&cli.StringFlag{
        Name:        "lang",
        Aliases:     []string{"l"},
				Value:       "english",
				Usage:       "language for the greeting",
				Destination: &language,
			},
		},
		Action: func(c *cli.Context) error {
			name := "someone"
			if c.NArg() > 0 {
				name = c.Args().Get(0)
			}
			if language == "spanish" {
				fmt.Println("Hola", name)
			} else {
				fmt.Println("Hello", name)
			}
			return nil
		},
	}

这段代码里既有 arguments 又有 flag 。在使用命令时，要先输入 flag 后输入 arg

go run main.go -lang=spanish wangshushuo

flag 部分有多种用法可选：

-lang=abc
--lang=abc
--lang abc

如果定义里 Aliase 还可以

-l abc

环境变量 #

定义 EnvVars 可以用来读取环境变量

app := &cli.App{
  Flags: []cli.Flag{
    &cli.StringFlag{
      Name:    "lang",
      Aliases: []string{"l"},
      Value:   "english",
      Usage:   "language for the greeting",
      EnvVars: []string{"LEGACY_COMPAT_LANG", "APP_LANG", "LANG"},
    },
  },
}

从文件中取值 #

FilePath

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app.Flags = []cli.Flag {
  &cli.StringFlag{
    Name: "password",
    Aliases: []string{"p"},
    Usage: "password for the mysql database",
    FilePath: "/etc/mysql/password",
  },
}

文件比环境变量的优先级高。

交互式的获取值 #

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var language string

prompt := promptui.Select{
	Label: "Select Day",
	Items: []string{"spanish", "english", "chinese"},
}

_, language, err := prompt.Run()

app := &cli.App{
	Action: func(c *cli.Context) error {
		name := "someone"
		if c.NArg() > 0 {
			name = c.Args().Get(0)
		}
		if language == "spanish" {
			fmt.Println("Hola", name)
		} else {
			fmt.Println("Hello", name)
		}
		return nil
	},
}