// Define the command and its arguments using codegangsta/cli app := cli.NewApp() app.Name = "myapp" app.Commands = []cli.Command{ { Name: "hello", Usage: "print a greeting", Action: func(c *cli.Context) error { fmt.Println("Hello, " + c.Args()[0]) return nil }, }, } // Parse the command arguments and execute err := app.Run(os.Args) if err != nil { log.Fatal(err) }In this example, we defined a command "hello" that takes an argument for a person's name and prints a greeting. The `Context` struct is used to access the command-line arguments and `Args` struct is used to read the argument passed to command-line. In summary, the package library "github.com.codegangsta.cli" provides a tool for building command-line interfaces in Go, while the `Context` struct and `Args` struct are used to hold variables and arguments respectively for the command being executed.