go - 命令行应用程序输出使用说明，即使我认为我已经正确使用它

Question

输入

go run site-downloader.go --url https://www.google.com

预期产出

Passed url: https://www.google.com

实际输出

Passed url: NAME:
   Site downloader - Follows an URL and downloads rendered html content. Follows and download anchor links to child pages recursively. Only follows relative links.

USAGE:
   site-downloader [global options] command [command options] [arguments...]

COMMANDS:
   help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --url value  Site url
   --help, -h   show help (default: false)

我的代码有什么问题？

package main

import (
    "fmt"
    "log"
    "os"

    "github.com/urfave/cli"
)

var app = cli.NewApp()

func info() {
    app.Name = "Site downloader"
    app.Usage = "Follows an URL and downloads rendered html content. Follows and download anchor links to child pages recursively. Only follows relative links."
}

func commands() string {
    var url string

    urlFlag := cli.StringFlag{
        Name:        "url",
        Usage:       "Site url",
        Destination: &url,
    }

    app.Flags = []cli.Flag{
        &urlFlag,
    }

    return url
}

func main() {
    info()
    var url = commands()

    fmt.Printf("Passed url: %v", url)

    err := app.Run(os.Args)
    if err != nil {
        log.Fatal(err)
    }
}

Answer 1

我认为您需要实现 Action而且检索网址也不是那样的，请检查此代码

    func commands() {
        var url string

        urlFlag := cli.StringFlag{
            Name:        "url",
            Usage:       "Site url",
            Destination: &url,
        }

        app.Flags = []cli.Flag{
            &urlFlag,
        }
    }

    func main() {
        info()
        commands()

        app.Action = func(c *cli.Context) error {
            fmt.Printf("Passed url: %v", c.String("url"))
            return nil
        }

        err := app.Run(os.Args)
        if err != nil {
            log.Fatal(err)
        }
    }

请注意，我从 func commands() 中删除了 return