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 (
  "log"
  "os"

  "github.com/urfave/cli"
)

func main() {
  err := cli.NewApp().Run(os.Args)
  if err != nil {
    log.Fatal(err)
  }
}

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"
)

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

  err := app.Run(os.Args)
  if 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