【golang】第三方命令行 cli 的使用

￡神魔★判官ぃ 2022-06-10 08:59 237阅读 0赞

引入包

###       ###

### "github.com/urfave/cli" ###

**结构体**

###      App 结构体定义了命令行的应用结构，如下很庞大的样子 ###

### // App is the main structure of a cli application. It is recommended that // an app be created with the cli.NewApp() function **type** App **struct** \{ // The name of the program. Defaults to path.Base(os.Args\[0\]) Name string // Full name of command for help, defaults to Name HelpName string // Description of the program. Usage string // Text to override the USAGE section of help UsageText string // Description of the program argument format. ArgsUsage string // Version of the program Version string // List of commands to execute Commands \[\]Command // List of flags to parse Flags \[\]Flag // Boolean to enable bash completion commands EnableBashCompletion bool // Boolean to hide built-in help command HideHelp bool // Boolean to hide built-in version flag and the VERSION section of help HideVersion bool // Populate on app startup, only gettable through method Categories() categories CommandCategories // An action to execute when the bash-completion flag is set BashComplete BashCompleteFunc // An action to execute before any subcommands are run, but after the context is ready  // If a non-nil error is returned, no subcommands are run Before BeforeFunc // An action to execute after any subcommands are run, but after the subcommand has finished  // It is run even if Action() panics After AfterFunc // The action to execute when no subcommands are specified  // Expects a \`cli.ActionFunc\` but will accept the \*deprecated\* signature of \`func(\*cli.Context) \{\}\`  // \*Note\*: support for the deprecated \`Action\` signature will be removed in a future version Action **interface**\{\} // Execute this function if the proper command cannot be found CommandNotFound CommandNotFoundFunc // Execute this function if an usage error occurs OnUsageError OnUsageErrorFunc // Compilation date Compiled time.Time // List of all authors who contributed Authors \[\]Author // Copyright of the binary if any Copyright string // Name of Author (Note: Use App.Authors, this is deprecated) Author string // Email of Author (Note: Use App.Authors, this is deprecated) Email string // Writer writer to write output to Writer io.Writer // ErrWriter writes error output ErrWriter io.Writer // Other custom info Metadata **map**\[string\]**interface**\{\} didSetup bool \} ###

// Context is a type that is passed through to
    // each Handler action in a cli application. Context
    // can be used to retrieve context-specific Args and
    // parsed command-line options.
    type Context struct {
           App           *App
           Command       Command
           flagSet       *flag.FlagSet
           setFlags      map[string]bool
           parentContext *Context
    }

**初始化 APP**

###       ###

### // NewApp creates a new cli Application with some reasonable defaults for Name, // Usage, Version and Action. **func** NewApp() \*App \{ **return** &App\{ Name: filepath.Base(os.Args\[0\]), HelpName: filepath.Base(os.Args\[0\]), Usage: "A new cli application", UsageText: "", Version: "0.0.0", BashComplete: DefaultAppComplete, Action: helpCommand.Action, Compiled: compileTime(), Writer: os.Stdout, \} \} ###

**例子主函数**

###       ###

### **const** (*usage* = "xxxxxxxxxxxxxx") ###

func main() {
           app := cli.NewApp()
           app.Name = "name"
           app.Usage = usage 
           app.Version = "xxxxx"
           app.Flags = []cli.Flag{
                  cli.BoolFlag{
                         Name:  "debug",
                         Usage: "enable debug output for logging",
                  },
                  cli.StringFlag{
                         Name:  "log",
                         Value: "/dev/null",
                         Usage: "set the log file path where internal debug information is written",
                  },
           }
           app.Commands = []cli.Command{  
                 createCommand, deleteCommand,
           }
           app.Before = func(context *cli.Context) error {
                  if context.GlobalBool("debug") {
                         logrus.SetLevel(logrus.DebugLevel)
                  }
                  if path := context.GlobalString("log"); path != "" {
                         f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND|os.O_SYNC, 0666)
                         if err != nil {
                                return err
                         }
                         logrus.SetOutput(f)
                  }
                  return nil
           }
     
           if err := app.Run(os.Args); err != nil {
                  fatal(err)
           }
    }

**例子子命令**

###      自命令可以使用模版，在 Action 中调用实现的函数 ###

### **var** createCommand = cli.Command\{ Name: "create", Usage: "create a xxxxx", ArgsUsage: \`xxxxxxx\`, Flags: \[\]cli.Flag\{ cli.StringFlag\{ Name: "bundle, b", Value: "", Usage: \`path to the root of directory, defaults to the current directory\`, \},\}, Action: **func**(context \*cli.Context) error \{ *do-something***return** nil \}, \} ###

**例子子命令**

###      自命令可以使用模版，在 Action 中调用实现的函数 ###

// loadSpec loads the specification from the provided path.
    func loadSpec(cPath string) (spec *specs.Spec, err error) {
           cf, err := os.Open(cPath)
           if err != nil {
                  if os.IsNotExist(err) {
                         return nil, fmt.Errorf("JSON specification file %s not found", cPath)
                  }
                  return nil, err
           }
           defer cf.Close()
    
           if err = json.NewDecoder(cf).Decode(&spec); err != nil {
                  return nil, err
           }
           return spec, validateProcessSpec(spec.Process)
    }

具体可以参考 runc 源码 main.go 文件