在Go里面应用中flag这一标准库，提供了很多我们在写命令行时需要的interface，然而如果你需要更强大更好的结构，可以试一下cli.go这个库。
利用cli.go来写命令行应用
定义命令和子命令
下面是一个例子:
package main import (
"fmt"
"os" "github.com/codegangsta/cli"
) func main() {
app := cli.NewApp()
app.Name = "jasperapp"
app.Usage = "sample command-line app by jasper"
app.Author = "Carter"
app.Email = "jasper@xxx.com"
app.Commands = []cli.Command{
{
Name: "read",
ShortName: "r",
Usage: "read something",
Subcommands: []cli.Command{
{
Name: "articles",
Usage: "read articles",
Action: readArticles,
},
{
Name: "tweets",
Usage: "read Tweets",
Action: readTweets,
},
},
},
}
app.Run(os.Args)
} func readArticles(ctx *cli.Context) {
fmt.Println("Go to http://www.opscoder.info to read articles!")
} func readTweets(ctx *cli.Context) {
fmt.Println("Go to http://www.opscoder.info to read our tweets!")
}
如果你不带参数去运行，你将会得到下面的帮助信息：
NAME:
jasperapp - sample command-line app by jasper USAGE:
jasperapp [global options] command [command options] [arguments...] VERSION:
0.0.0 AUTHOR:
Carter - <jasper@xxx.com> COMMANDS:
read, r read something
help, h Shows a list of commands or help for one command GLOBAL OPTIONS:
--help, -h show help
--version, -v print the version
我们定义一个read子命令，它有articles和tweet两个命令：
jasperapp read articles
输出为：
Go to http://www.opscoder.info to read articles!
或是运行：
jasperapp read tweets
输出为：
Go to http://www.opscoder.info to read our tweets!
使用context
每个动作都有一个context，在下面的例子中函数readArticles和readTweets接收一个参数，我们可以这样使用：
func readArticles(ctx *cli.Context) {
fmt.Printf("The first argument was: %s", ctx.Args().First())
}
现在运行jasperapp read articles please将会输出：
The first argument was: please
使用flags
为了展示flags的用法，我们稍微修改一下tweets子命令：
{
Name: "tweets",
Usage: "read Tweets",
Flags: []cli.Flag{
cli.StringFlag{
Name: "account",
Value: "TheJasper",
Usage: "name of Twitter account",
},
},
Action: readTwitter,
},
其中readTweets函数这么写：
func readTwitter(ctx *cli.Context) {
fmt.Printf("Go to http://www.opscoder.info/%s to read tweets!", ctx.String("account"))
}
现在让我们编译结果并查看下tweets子命令的帮助信息:
jasperapp read tweets --help
输出如下：
NAME:
tweets - read Tweets USAGE:
command tweets [command options] [arguments...] OPTIONS:
--account 'TheJasper' name of Twitter account
现在让我们试试：
$ jasperapp read tweets
Go to http://www.opscoder.info/TheJasper to read tweets! $ jasperapp read tweets --account codegangsta
Go to http://www.opscoder.info/codegangsta to read tweets!
总结
Cli.go还有很多自定义的东西，具体可以参考Godoc的文档。