Check if a environment variable is set in Go (Golang)

os.LookupEnv function can be used to check whether a particular environment variable is set or not. It returns a bool which is true if the given env variable set otherwise false. Let’s see a working code:

package main
import (
"fmt"
"log"
"os"
)
func main() {
//Set env a to b
err := os.Setenv("a", "x")
if err != nil {
log.Fatal(err)
}
val, present := os.LookupEnv("a")
fmt.Printf("a env variable present: %t\n", present)
fmt.Println(val)
val, present = os.LookupEnv("b")
fmt.Printf("b env variable present: %t\n", present)
}

Output:

a env variable present: true
x
b env variable present: false

env