How to Access Command-Line Arguments in Go

Created May 6, 2022 at 16:12

Modified May 6, 2022 at 17:15

Using os.Args Variable

You can access the command-line arguments using the os.Args variable.

Note that the first value in this slice is the path to the program, and os.Args[1:] holds the arguments to the program. For example,

package main

import (
  "fmt"
  "os"
)

// Command-Line Arguments
// go run main.go -path=/home
func main() {

  fmt.Println(os.Args[0])
  fmt.Println(os.Args[1])
}

./main
--path=/home

Using flag Package

Package flag implements command-line flag parsing.

Go provides a `flag` package supporting basic command-line flag parsing. We'll use this package to implement our example command-line program.

See the following example:

package main

import (
  "flag"
  "fmt"
)

// Command-Line Arguments
// go run main.go -path=/home -n=10 -svar=ss
func main() {

  pathPtr := flag.String("path", "tmp", "Path")

  nPtr := flag.Int("n", 42, "an int")

  var svar string
  flag.StringVar(&svar, "svar", "bar", "a string var")

  flag.Parse()

  fmt.Println(*pathPtr)
  fmt.Println(*nPtr)
  fmt.Println(svar)
  fmt.Println(flag.Args())
}