Command-Line Arguments

Command-line arguments are a common way to parameterize execution of programs. For example, go run hello.go uses run and hello.go arguments to the go program.

package main

import (
    "fmt"
    "os"
)

func main() {

    // os.Args provides access to raw command-line arguments.
    // Note that the first value in this slice 
    // is the path to the program, and os.Args[1:] 
    // holds the arguments to the program.
    argsWithProg := os.Args
    argsWithoutProg := os.Args[1:]

    // You can get individual args with normal indexing.
    arg := os.Args[3]

    fmt.Println(argsWithProg)
    fmt.Println(argsWithoutProg)
    fmt.Println(arg)
}

To experiment with command-line arguments it’s best to build a binary with go build first.

$ go build command-line-arguments.go
$ ./command-line-arguments a b c d
[./command-line-arguments a b c d]       
[a b c d]
c