# Go cheatsheet - Env

## Env

Functions to operate environment variables:
* `os.Getenv`: get env variable by name, if not set, return empty string
* `os.LookupEnv`: return (value, exists)
* `os.Setenv`: set env variable value
* `os.Unsetenv`: Unset env variable

Sample code:
```go
package main

import (
	"fmt"
	"os"
)

func main() {
	dbConn := os.Getenv("DB_CONN")
	fmt.Println("DB Conn:", dbConn)

	dbConn, exists := os.LookupEnv("DB_CONN")
	if !exists {
		fmt.Println("Env is not set")
	} else {
		fmt.Println("DB Conn:", dbConn)
	}

	os.Setenv("DB_CONN", "mongodb://abc")
	dbConn = os.Getenv("DB_CONN")
	fmt.Println("DB Conn:", dbConn)    // mongodb://abc

	os.Unsetenv("DB_CONN")
}
```