Getting Started

One of the philosophies behind cli is that an API should be playful and full of discovery. So a cli app can be as little as one line of code in main().

package main

import (
    "os"

    "github.com/urfave/cli/v2"
)

func main() {
    (&cli.App{}).Run(os.Args)
}

This app will run and show help text, but is not very useful. Let's give an action to execute and some help documentation:

package main

import (
    "fmt"
    "log"
    "os"

    "github.com/urfave/cli/v2"
)

func main() {
    app := &cli.App{
        Name:  "boom",
        Usage: "make an explosive entrance",
        Action: func(*cli.Context) error {
            fmt.Println("boom! I say!")
            return nil
        },
    }

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

Running this already gives you a ton of functionality, plus support for things like subcommands and flags, which are covered below.

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Last update: August 15, 2022