example.env.php

<?php
/**
 * Craft-Multi-Environment (CMS)
 * @author    nystudio107
 * @copyright Copyright (c) 2017 nystudio107
 * @link      https://nystudio107.com/
 * @package   craft-multi-environment
 * @since     1.0.4
 * @license   MIT
 *
 * This file should be renamed to '.env.php' and it should reside in your root
 * project directory.  Add '/.env.php' to your .gitignore.  See below for production
 * usage notes.
 */

// Determine the incoming protocol
if (isset($_SERVER['HTTPS']) && (strcasecmp($_SERVER['HTTPS'], 'on') === 0 || $_SERVER['HTTPS'] == 1)
    || isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strcasecmp($_SERVER['HTTP_X_FORWARDED_PROTO'], 'https') === 0
) {
    $protocol = "https://";
} else {
    $protocol = "http://";
}
// Determine the server hostname
$httpHost = isset($_SERVER['HTTP_HOST']) ? $_SERVER['HTTP_HOST'] : '';
// The $craftEnvVars are all auto-prefixed with CRAFTENV_ -- you can add
// whatever you want here and access them via getenv() using the prefixed name
$craftEnvVars = array(
    // The Craft environment we're running in ('local', 'staging', 'live', etc.).
    'CRAFT_ENVIRONMENT' => 'REPLACE_ME',

    // The database server name or IP address. Usually this is 'localhost' or '127.0.0.1'.
    'DB_HOST' => 'REPLACE_ME',

    // The name of the database to select.
    'DB_NAME' => 'REPLACE_ME',

    // The database username to connect with.
    'DB_USER' => 'REPLACE_ME',

    // The database password to connect with.
    'DB_PASS' => 'REPLACE_ME',

    // The site url to use; it can be hard-coded as well
    'SITE_URL' => $protocol . $httpHost . '/',

    // The base url environmentVariable to use for Assets; it can be hard-coded as well
    'BASE_URL' => $protocol . $httpHost . '/',

    // The base path environmentVariable for Assets; it can be hard-coded as well
    'BASE_PATH' => realpath(dirname(__FILE__)) . '/public/',
);

// Set all of the .env values, auto-prefixed with `CRAFTENV_`
foreach ($craftEnvVars as $key => $value) {
    putenv("CRAFTENV_{$key}={$value}");
}

/**
 * For production environments, this .env.php file can be used, or preferably,
 * (for security & speed), set the $_ENV variables directly from the server config.
 *
 * Apache - inside the <VirtualHost> block:

SetEnv CRAFTENV_CRAFT_ENVIRONMENT "REPLACE_ME"
SetEnv CRAFTENV_DB_HOST "REPLACE_ME"
SetEnv CRAFTENV_DB_NAME "REPLACE_ME"
SetEnv CRAFTENV_DB_USER "REPLACE_ME"
SetEnv CRAFTENV_DB_PASS "REPLACE_ME"
SetEnv CRAFTENV_SITE_URL "REPLACE_ME"
SetEnv CRAFTENV_BASE_URL "REPLACE_ME"
SetEnv CRAFTENV_BASE_PATH "REPLACE_ME"

 * Nginx - inside the server {} or location ~ \.php$ {} block:

fastcgi_param CRAFTENV_CRAFT_ENVIRONMENT "REPLACE_ME";
fastcgi_param CRAFTENV_DB_HOST "REPLACE_ME";
fastcgi_param CRAFTENV_DB_NAME "REPLACE_ME";
fastcgi_param CRAFTENV_DB_USER "REPLACE_ME";
fastcgi_param CRAFTENV_DB_PASS "REPLACE_ME";
fastcgi_param CRAFTENV_SITE_URL "REPLACE_ME";
fastcgi_param CRAFTENV_BASE_URL "REPLACE_ME";
fastcgi_param CRAFTENV_BASE_PATH "REPLACE_ME";

 */