Exit Codes

Calling App.Run will not automatically call os.Exit, which means that by default the exit code will "fall through" to being 0. An explicit exit code may be set by returning a non-nil error that fulfills cli.ExitCoder, or a cli.MultiError that includes an error that fulfills cli.ExitCoder, e.g.:

package main

import (
  "log"
  "os"

  "github.com/urfave/cli"
)

func main() {
  app := cli.NewApp()
  app.Flags = []cli.Flag{
    cli.BoolFlag{
      Name:  "ginger-crouton",
      Usage: "Add ginger croutons to the soup",
    },
  }
  app.Action = func(ctx *cli.Context) error {
    if !ctx.Bool("ginger-crouton") {
      return cli.NewExitError("Ginger croutons are not in the soup", 86)
    }
    return nil
  }

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