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如何在golang中使用cobra庫(kù)?很多新手對(duì)此不是很清楚,為了幫助大家解決這個(gè)難題,下面小編將為大家詳細(xì)講解,有這方面需求的人可以來(lái)學(xué)習(xí)下,希望你能有所收獲。
cobra 是 go 語(yǔ)言的一個(gè)庫(kù),可以用于編寫(xiě)命令行工具。通常我們可以看到git pull
、docker container start
、apt install
等等這樣命令,都可以很容易用corba來(lái)實(shí)現(xiàn),另外,go 語(yǔ)言是很容易編譯成一個(gè)二進(jìn)制文件,本文將實(shí)現(xiàn)一個(gè)簡(jiǎn)單的命令行工具。
具體寫(xiě)一個(gè)例子, 設(shè)計(jì)一個(gè)命令叫blog
, 有四個(gè)子命令
blog new [post-name] :創(chuàng)建一篇新的blog blog list :列出當(dāng)前有哪些文章 blog delete [post-name]: 刪除某一篇文章 blog edit [post-name]:編輯某一篇文章
計(jì)劃有以下幾個(gè)步驟
創(chuàng)建模塊
用cobra的命令行,創(chuàng)建命令行入口
用cobra的命令行,創(chuàng)建子命令
編寫(xiě)功能邏輯
$ go mod init github.com/shalk/blog go: creating new go.mod: module github.com/shalk/blog
說(shuō)到命令行,可能會(huì)想到bash的getopt 或者 java 的jcommand,可以解析各種風(fēng)格的命令行,但是通常這些命令行都有固定的寫(xiě)法,這個(gè)寫(xiě)法一般還記不住要找一個(gè)模板參考以下。cobra除了可以解析命令行之外,還提供了命令行,可以生成模板。先安裝這個(gè)命令行, 并且把庫(kù)的依賴加到go.mod里
$ go get -u github.com/spf13/cobra/cobra
cobra會(huì)安裝到$GOPATH\bin
目錄下,注意環(huán)境變量中把它加入PATH中
$ cobra init --pkg-name github.com/shalk/blog -a shalk -l mit Your Cobra applicaton is ready at D:\code\github.com\shalk\blog
目錄結(jié)構(gòu)如下:
./cmd ./cmd/root.go ./go.mod ./go.sum ./LICENSE ./main.go
編譯一下
go build -o blog .
執(zhí)行一下
$blog -h A longer description that spans multiple lines and likely contains examples and usage of using your application. For example: Cobra is a CLI library for Go that empowers applications. This application is a tool to generate the needed files to quickly create a Cobra application.
命令行就創(chuàng)建好了,看上去一行代碼也不用寫(xiě),由于隨著了解的深入,后面需要調(diào)整生成的代碼,還是要了解一下cobra代碼的套路。
有三個(gè)概念,command、flag和args ,例如:
go get -u test.com/a/b
這里 get 就是commond(這里比較特殊), -u 就是flag, test.com/a/b 就是args
那么命令行就是有三部分構(gòu)成,所以需要定義好這個(gè)
命令自身的一些基本信息,用command表示,具體對(duì)象是 cobra.Command
命令的一些標(biāo)致或者選項(xiàng),用flag表示,具體對(duì)象是 flag.FlagSet
最后的參數(shù),用args表示,通常是[]string
還有一個(gè)概念是子命令,比如get就是go的子命令,這是一個(gè)樹(shù)狀結(jié)構(gòu)的關(guān)系。
我可以使用go命令,也可以使用 go get命令
例如: root.go,定義了root命令,另外在init里面 定義了flag,如果它本身有具體執(zhí)行,就填充Run字段。
// rootCmd represents the base command when called without any subcommands var rootCmd = &cobra.Command{ Use: "blog", Short: "A brief description of your application", Long: `A longer description that spans multiple lines and likely contains examples and usage of using your application. For example: Cobra is a CLI library for Go that empowers applications. This application is a tool to generate the needed files to quickly create a Cobra application.`, // Uncomment the following line if your bare application // has an action associated with it: // Run: func(cmd *cobra.Command, args []string) { }, } // Execute adds all child commands to the root command and sets flags appropriately. // This is called by main.main(). It only needs to happen once to the rootCmd. func Execute() { if err := rootCmd.Execute(); err != nil { fmt.Println(err) os.Exit(1) } } func init() { cobra.OnInitialize(initConfig) // Here you will define your flags and configuration settings. // Cobra supports persistent flags, which, if defined here, // will be global for your application. rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.blog.yaml)") // Cobra also supports local flags, which will only run // when this action is called directly. rootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle") }
如果需要子命令,就需要在init 里,給 rootCmd.AddCommand() 其他的command,其他的子命令通常也會(huì)單獨(dú)用一個(gè)文件編寫(xiě),并且有一個(gè)全局變量,讓rootCmd可以add它
D:\code\github.com\shalk\blog>cobra add new new created at D:\code\github.com\shalk\blog D:\code\github.com\shalk\blog>cobra add delete delete created at D:\code\github.com\shalk\blog D:\code\github.com\shalk\blog>cobra add list list created at D:\code\github.com\shalk\blog D:\code\github.com\shalk\blog>cobra add edit edit created at D:\code\github.com\shalk\blog
cmd 目錄下增加了 new.go, delete.go,list.go,edit.go
new.go
var newCmd = &cobra.Command{ Use: "new", Short: "create new post", Long: `create new post `, Args: func(cmd *cobra.Command, args []string) error { if len(args) != 1 { return errors.New("requires a color argument") } return nil }, Run: func(cmd *cobra.Command, args []string) { fileName := "posts/" + args[0] err := os.Mkdir("posts", 644) if err != nil { log.Fatal(err) } _, err = os.Stat( fileName) if os.IsNotExist(err) { file, err := os.Create(fileName) if err != nil { log.Fatal(err) } log.Printf("create file %s", fileName) defer file.Close() } else { } }, }
list.go
var listCmd = &cobra.Command{ Use: "list", Short: "list all blog in posts", Long: `list all blog in posts `, Run: func(cmd *cobra.Command, args []string) { _, err := os.Stat("posts") if os.IsNotExist(err) { log.Fatal("posts dir is not exits") } dirs, err := ioutil.ReadDir("posts") if err != nil { log.Fatal("read posts dir fail") } fmt.Println("------------------") for _, dir := range dirs { fmt.Printf(" %s\n", dir.Name() ) } fmt.Println("------------------") fmt.Printf("total: %d blog\n", len(dirs)) }, }
delete.go
var deleteCmd = &cobra.Command{ Use: "delete", Short: "delete a post", Long: `delete a post`, Args: func(cmd *cobra.Command, args []string) error { if len(args) != 1 { return errors.New("requires a color argument") } if strings.Contains(args[0],"/") || strings.Contains(args[0],"..") { return errors.New("posts name should not contain / or .. ") } return nil }, Run: func(cmd *cobra.Command, args []string) { fileName := "./posts/" + args[0] stat, err := os.Stat(fileName) if os.IsNotExist(err) { log.Fatalf("post %s is not exist", fileName) } if stat.IsDir() { log.Fatalf("%s is dir ,can not be deleted", fileName) } err = os.Remove(fileName) if err != nil { log.Fatalf("delete %s fail, err %v", fileName, err) } else { log.Printf("delete post %s success", fileName) } }, }
edit.go 這個(gè)有一點(diǎn)麻煩,因?yàn)槿绻{(diào)用一個(gè)程序比如vim 打開(kāi)文件,并且golang程序本身要退出,需要detach。暫時(shí)放一下(TODO)
我是window測(cè)試,linux 更簡(jiǎn)單一點(diǎn)
PS D:\code\github.com\shalk\blog> go build -o blog.exe . PS D:\code\github.com\shalk\blog> .\blog.exe list ------------------ ------------------ total: 0 blog PS D:\code\github.com\shalk\blog> .\blog.exe new blog1.md 2020/07/26 22:37:15 create file posts/blog1.md PS D:\code\github.com\shalk\blog> .\blog.exe new blog2.md 2020/07/26 22:37:18 create file posts/blog2.md PS D:\code\github.com\shalk\blog> .\blog.exe new blog3.md 2020/07/26 22:37:20 create file posts/blog3.md PS D:\code\github.com\shalk\blog> .\blog list ------------------ blog1.md blog2.md blog3.md ------------------ total: 3 blog PS D:\code\github.com\shalk\blog> .\blog delete blog1.md 2020/07/26 22:37:37 delete post ./posts/blog1.md success PS D:\code\github.com\shalk\blog> .\blog list ------------------ blog2.md blog3.md ------------------ total: 2 blog PS D:\code\github.com\shalk\blog> ls .\posts\ 目錄: D:\code\github.com\shalk\blog\posts Mode LastWriteTime Length Name ---- ------------- ------ ---- -a---- 2020/7/26 22:37 0 blog2.md -a---- 2020/7/26 22:37 0 blog3.md PS D:\code\github.com\shalk\blog>
golang可以做服務(wù)器端開(kāi)發(fā),但golang很適合做日志處理、數(shù)據(jù)打包、虛擬機(jī)處理、數(shù)據(jù)庫(kù)代理等工作。在網(wǎng)絡(luò)編程方面,它還廣泛應(yīng)用于web應(yīng)用、API應(yīng)用等領(lǐng)域。
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