Post a simple slack message using a bot. See my blog post at https://gophp.io/developing-slack-bots-with-php-part-1 for a guide on how this works.

slack.php

<?php
/**
 * Created by Markus Tenghamn @ GoPHP.io
 * Date: 2018-12-29
 * Time: 12:47
 * 
 * Post a simple slack message using a bot. You can run this in a console with 'php slack.php'
 *
 * See my blog post at https://gophp.io/developing-slack-bots-with-php-part-1 for a guide on how this works
 */

// Slack endpoint for chat.postMessage
$url = "https://slack.com/api/chat.postMessage";

// Required fields taken from docs at https://api.slack.com/methods/chat.postMessage
$fields = [
	'token'      => "your-token",
	'channel'    => "#general",
	'text'       => 'This is a test message from GoPHP.io'
];

$fields_string = http_build_query($fields);

$ch = curl_init();
curl_setopt($ch,CURLOPT_URL, $url);
curl_setopt($ch,CURLOPT_POST, count($fields));
curl_setopt($ch,CURLOPT_POSTFIELDS, $fields_string);
curl_setopt($ch,CURLOPT_RETURNTRANSFER, true);

$result = curl_exec($ch);
print_r($result);