Golang : Set, Get and List environment variables

Environment variables allow Unix programs to store configuration information and the program behaviour maybe altered if the environment variables related to the program changed during runtime. Golang os package allows a Go program to set, get and list the environment variables.

This example below will show you how to set the environment variables, get them and list them.

 package main

 import (
 "fmt"
 "os"
 "strings"
 )

 func main() {

 // set environment variable example

 os.Setenv("testvar", "123")

 testvar := os.Getenv("testvar")

 fmt.Printf("testvar value is %v", testvar)

 // what happened if try to get a non existence environment variable

 fmt.Println(os.Getenv("testnone")) // just return empty string


 // list out the
 var env []string
 env = os.Environ()

 fmt.Println("List of Environtment variables : \n")

 for index, value := range env {
 name := strings.Split(value, "=") // split by = sign

 fmt.Printf("[%d] %s : %v\n", index, name[0], name[1])
 }


 }

Sample output(depending on your machine) :

testvar value is 123

List of Environtment variables :

[0] TERM_PROGRAM : iTerm.app

[1] SHELL : /bin/bash

[2] TERM : xterm-256color

[3] TMPDIR : /var/folders/nd/5m9x1v_j4338y_t1rg02zbph0000gn/T/

...

[18] LC_CTYPE : UTF-8

[19] _ : /usr/local/go/bin/go

[20] testvar : 123

To set value for testnone variable, you can do it in the command line :

export testnone=456

and the result from executing the same code again will look like this :

testvar value is 123456 (456 is the testnone variable)

List of Environtment variables :

Reference :

http://golang.org/pkg/os/