How to easily post to slack channel with PHP

post_slack.php

<?php
// Your slack token
$token = 'YOURTOKEN';

// Your slack channel (e.g. #general)
$channel = '#general';

// Post message
$text = "<!channel>Hello World!";

$text = urlencode($text);
$channel = urlencode($channel);
$url = "https://slack.com/api/chat.postMessage?token={$token}&channel={$channel}&text={$text}";

file_get_contents($url);