Flags and Arguments

Go provides support for creating command-line interface tools. Many times, when we are writing Go programs that are executables, they need to accept various inputs. These inputs could include the location of a file, a value to run the program in the debug state, getting help to run the program, and more. All of this is made possible by a package in the Go standard library called flag. It is used to allow the passing of arguments to the program. A flag is an argument that is passed to a Go program. The order of the flags being passed to the Go program using the flag package does not matter to Go.

To define your flag, you must know the flag type you will be accepting. The flag package provides many functions for defining flags. Here is a sample list:

func Bool(name string, value bool, usage string) *bool
func Duration(name string, value time.Duration, usage string) *time.Duration
func Float64(name string, value float64, usage string) *float64
func Int(name string...