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Cli-X is a command line library for Go, inspired byspf13/cobra.

• 📦struct based API: Similar tocobra,go-clix/cli features astruct basedAPI for easy composition and discovery of available options.
• 🚸Subcommands:cli.Command can be nested for agitlike experience.
• 📌Flags: Every command has it's own set of flags. POSIX compliantusingspf13/pflag.
• 👥Aliases: Commands can have multiple names, sobreaking changes can easily be mitigated.
• 🎯Go based completion:<TAB> completion is supported forbash,zsh andfish. But you can generate suggestions usingGo code!

Add the library to your project:

$ go get github.com/go-clix/cli

Then set up your root command:

package mainimport ("fmt""github.com/go-clix/cli")funcmain() {// create the root commandrootCmd:= cli.Command{Use:"greet",Short:"print a message",Run:func(cmd*cli.Command,args []string)error {fmt.Println("Hello from Cli-X!")        },    }// run and check for errorsiferr:=rootCmd.Execute();err!=nil {fmt.Println(err)os.Exit(1)    }}

Every command may have children:

// use a func to return a Command instead of// a global variable and `init()`funcapplyCmd()*cli.Command {cmd:=&cli.Command{Use:"apply",Short:"apply the changes"    }cmd.Run=func(cmd*cli.Command,args []string)error {fmt.Println("applied",args[0])    }returncmd}funcmain() {rootCmd:=&cli.Comand{Use:"kubectl",Short:"Kubernetes management tool",    }// add the child commandrootCmd.AddChildren(applyCmd(),    )// run and check for errorsiferr:=rootCmd.Execute();err!=nil {fmt.Println(err)os.Exit(1)    }}

Note: Do not use theinit() function for setting up your commands.Create constructors as shown above!

Apflag.FlagSet can be accessed per command using*Command.Flags():

funcapplyCmd()*cli.Command {cmd:=&cli.Command{Use:"apply",Short:"apply the changes"    }force:=cmd.Flags().BoolP("force","f",false,"skip checks")cmd.Run=func(cmd*cli.Command,args []string)error {fmt.Println("applied",args[0])if*force {fmt.Println("The force was with us.")        }    }returncmd}

To make theapply subcommand also available asmake anddo:

funcapplyCmd()*cli.Command {cmd:=&cli.Command{Use:"apply",Aliases: []string{"make","do"},Short:"apply the changes"    }}

Keep in mind that in--help outputs the command will still be calledapply.

Cli-X has a very powerful cli completion system, based onposener/complete.

It is powerful, because suggestions come directly from the Go application, notfrom abash script or similar.

Command and Flag names are automatically suggested, custom suggestions can beimplemented forpositional arguments andflagvalues:

Custom suggestions for flag values can be set up usingCommand.Predictors.

To do so, you need to add acomplete.Predictor for that flag. Cli-X has anumber of predefined ones:

• PredictAny(): Predicts available files and directories, likebash does whenhaving no better idea
• PredictNone(): Predicts literally nothing. No suggestions will be shown.
• PredictSet(...string): Suggests from a predefined slice of options

If that's not sufficient, usePredictFunc(func(complete.Args) []string) tocreate your own.

import ("github.com/posener/complete""github.com/go-clix/cli")funclogsCmd()*cli.Command {cmd:=&cli.Command{Use:"logs",Short:"show logs of a pod",Predictors:map[string]complete.Predictor{"output":cli.PredictSet("lines","json","logfmt"),        },    }output:=cmd.Flags().StringP("output","o","lines","one of [lines, json, logfmt]")}

For positional arguments, Cli-X uses a slightly differentinterface, to allowvalidation as well:

interface {Validate(args []string)errorPredict(Args) []string}

Predefined options are also available:

• ArgsAny(): accepts any number args, predicts files and directories
• ArgsExact(n): acceptsexactlyn arguments. Predicts files and directories.
• ArgsRange(n, m): accepts betweenn andm arguments (inclusive). Predicts files and directories.
• ArgsNone(): acceptsno args and predicts nothing.
• ArgsSet(...string): Acceptsone argument, which MUST be included in thegiven set. Predicts the values from the set.

import ("github.com/posener/complete""github.com/go-clix/cli")funcapplyCmd()*cli.Command {cmd:=&cli.Command{Use:"logs",Short:"show logs of a pod",// we expect one argument which can be anythingArgs:cli.ArgsExact(1),    }}