golang中命令行庫(kù)cobra的使用方法示例
簡(jiǎn)介
Cobra既是一個(gè)用來(lái)創(chuàng)建強(qiáng)大的現(xiàn)代CLI命令行的golang庫(kù),也是一個(gè)生成程序應(yīng)用和命令行文件的程序。下面是Cobra使用的一個(gè)演示:
Cobra提供的功能
- 簡(jiǎn)易的子命令行模式,如 app server, app fetch等等
- 完全兼容posix命令行模式
- 嵌套子命令subcommand
- 支持全局,局部,串聯(lián)flags
- 使用Cobra很容易的生成應(yīng)用程序和命令,使用cobra create appname和cobra add cmdname
- 如果命令輸入錯(cuò)誤,將提供智能建議,如 app srver,將提示srver沒(méi)有,是否是app server
- 自動(dòng)生成commands和flags的幫助信息
- 自動(dòng)生成詳細(xì)的help信息,如app help
- 自動(dòng)識(shí)別-h,--help幫助flag
- 自動(dòng)生成應(yīng)用程序在bash下命令自動(dòng)完成功能
- 自動(dòng)生成應(yīng)用程序的man手冊(cè)
- 命令行別名
- 自定義help和usage信息
- 可選的緊密集成的viper apps
如何使用
上面所有列出的功能我沒(méi)有一一去使用,下面我來(lái)簡(jiǎn)單介紹一下如何使用Cobra,基本能夠滿足一般命令行程序的需求,如果需要更多功能,可以研究一下源碼github。
安裝cobra
Cobra是非常容易使用的,使用go get來(lái)安裝最新版本的庫(kù)。當(dāng)然這個(gè)庫(kù)還是相對(duì)比較大的,可能需要安裝它可能需要相當(dāng)長(zhǎng)的時(shí)間,這取決于你的速網(wǎng)。安裝完成后,打開(kāi)GOPATH目錄,bin目錄下應(yīng)該有已經(jīng)編譯好的cobra.exe程序,當(dāng)然你也可以使用源代碼自己生成一個(gè)最新的cobra程序。
> go get -v github.com/spf13/cobra/cobra
使用cobra生成應(yīng)用程序
假設(shè)現(xiàn)在我們要開(kāi)發(fā)一個(gè)基于CLIs的命令程序,名字為demo。首先打開(kāi)CMD,切換到GOPATH的src目錄下[^1],執(zhí)行如下指令:
[^1]:cobra.exe只能在GOPATH目錄下執(zhí)行
src> ..\bin\cobra.exe init demo Your Cobra application is ready at C:\Users\liubo5\Desktop\transcoding_tool\src\demo Give it a try by going there and running `go run main.go` Add commands to it by running `cobra add [cmdname]`
在src目錄下會(huì)生成一個(gè)demo的文件夾,如下:
▾ demo
▾ cmd/
root.go
main.go
如果你的demo程序沒(méi)有subcommands,那么cobra生成應(yīng)用程序的操作就結(jié)束了。
如何實(shí)現(xiàn)沒(méi)有子命令的CLIs程序
接下來(lái)就是可以繼續(xù)demo的功能設(shè)計(jì)了。例如我在demo下面新建一個(gè)包,名稱(chēng)為imp。如下:
▾ demo
▾ cmd/
root.go
▾ imp/
imp.go
imp_test.go
main.go
imp.go文件的代碼如下:
package imp import( "fmt" ) func Show(name string, age int) { fmt.Printf("My Name is %s, My age is %d\n", name, age) }
demo程序成命令行接收兩個(gè)參數(shù)name和age,然后打印出來(lái)。打開(kāi)cobra自動(dòng)生成的main.go文件查看:
// Copyright © 2016 NAME HERE <EMAIL ADDRESS> // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package main import "demo/cmd" func main() { cmd.Execute() }
可以看出main函數(shù)執(zhí)行cmd包,所以我們只需要在cmd包內(nèi)調(diào)用imp包就能實(shí)現(xiàn)demo程序的需求。接著打開(kāi)root.go文件查看:
// Copyright © 2016 NAME HERE <EMAIL ADDRESS> // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package cmd import ( "fmt" "os" "github.com/spf13/cobra" "github.com/spf13/viper" ) var cfgFile string // RootCmd represents the base command when called without any subcommands var RootCmd = &cobra.Command{ Use: "demo", 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 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 $HOME/.demo.yaml)") // Cobra also supports local flags, which will only run // when this action is called directly. RootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle") } // initConfig reads in config file and ENV variables if set. func initConfig() { if cfgFile != "" { // enable ability to specify config file via flag viper.SetConfigFile(cfgFile) } viper.SetConfigName(".demo") // name of config file (without extension) viper.AddConfigPath("$HOME") // adding home directory as first search path viper.AutomaticEnv() // read in environment variables that match // If a config file is found, read it in. if err := viper.ReadInConfig(); err == nil { fmt.Println("Using config file:", viper.ConfigFileUsed()) } }
從源代碼來(lái)看cmd包進(jìn)行了一些初始化操作并提供了Execute接口。十分簡(jiǎn)單,其中viper是cobra集成的配置文件讀取的庫(kù),這里不需要使用,我們可以注釋掉(不注釋可能生成的應(yīng)用程序很大約10M,這里沒(méi)喲用到最好是注釋掉)。cobra的所有命令都是通過(guò)cobra.Command這個(gè)結(jié)構(gòu)體實(shí)現(xiàn)的。為了實(shí)現(xiàn)demo功能,顯然我們需要修改RootCmd。修改后的代碼如下:
// Copyright © 2016 NAME HERE <EMAIL ADDRESS> // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package cmd import ( "fmt" "os" "github.com/spf13/cobra" // "github.com/spf13/viper" "demo/imp" ) //var cfgFile string var name string var age int // RootCmd represents the base command when called without any subcommands var RootCmd = &cobra.Command{ Use: "demo", Short: "A test demo", Long: `Demo is a test appcation for print things`, // Uncomment the following line if your bare application // has an action associated with it: Run: func(cmd *cobra.Command, args []string) { if len(name) == 0 { cmd.Help() return } imp.Show(name, age) }, } // Execute adds all child commands to the root command 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 $HOME/.demo.yaml)") // Cobra also supports local flags, which will only run // when this action is called directly. // RootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle") RootCmd.Flags().StringVarP(&name, "name", "n", "", "person's name") RootCmd.Flags().IntVarP(&age, "age", "a", 0, "person's age") } // initConfig reads in config file and ENV variables if set. //func initConfig() { // if cfgFile != "" { // enable ability to specify config file via flag // viper.SetConfigFile(cfgFile) // } // viper.SetConfigName(".demo") // name of config file (without extension) // viper.AddConfigPath("$HOME") // adding home directory as first search path // viper.AutomaticEnv() // read in environment variables that match // // If a config file is found, read it in. // if err := viper.ReadInConfig(); err == nil { // fmt.Println("Using config file:", viper.ConfigFileUsed()) // } //}
到此demo的功能已經(jīng)實(shí)現(xiàn)了,我們編譯運(yùn)行一下看看實(shí)際效果:
>demo.exe
Demo is a test appcation for print thingsUsage:
demo [flags]Flags:
-a, --age int person's age
-h, --help help for demo
-n, --name string person's name
>demo -n borey --age 26
My Name is borey, My age is 26
如何實(shí)現(xiàn)帶有子命令的CLIs程序
在執(zhí)行cobra.exe init demo之后,繼續(xù)使用cobra為demo添加子命令test:
src\demo>..\..\bin\cobra add test test created at C:\Users\liubo5\Desktop\transcoding_tool\src\demo\cmd\test.go
在src目錄下demo的文件夾下生成了一個(gè)cmd\test.go文件,如下:
▾ demo
▾ cmd/
root.go
test.go
main.go
接下來(lái)的操作就和上面修改root.go文件一樣去配置test子命令。效果如下:
src\demo>demo Demo is a test appcation for print things Usage: demo [flags] demo [command] Available Commands: test A brief description of your command Flags: -a, --age int person's age -h, --help help for demo -n, --name string person's name Use "demo [command] --help" for more information about a command.
可以看出demo既支持直接使用標(biāo)記flag,又能使用子命令
src\demo>demo test -h A longer description that spans multiple lines and likely contains examples and usage of using your command. 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. Usage: demo test [flags]
調(diào)用test命令輸出信息,這里沒(méi)有對(duì)默認(rèn)信息進(jìn)行修改。
src\demo>demo tst Error: unknown command "tst" for "demo" Did you mean this? test Run 'demo --help' for usage. unknown command "tst" for "demo" Did you mean this? test
這是錯(cuò)誤命令提示功能
OVER
Cobra的使用就介紹到這里,更新細(xì)節(jié)可去github詳細(xì)研究一下。這里只是一個(gè)簡(jiǎn)單的使用入門(mén)介紹,如果有錯(cuò)誤之處,敬請(qǐng)指出,謝謝~
總結(jié)
以上就是這篇文章的全部?jī)?nèi)容了,希望本文的內(nèi)容對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值,如果有疑問(wèn)大家可以留言交流,謝謝大家對(duì)腳本之家的支持。
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