Check for CLI script call.

is_cli.php

<?php
/**
 * This function checks on various environments for script call via CLI.
**/

function is_cli()
{
	if ( defined('STDIN') )
	{
		return true;
	}

	if ( php_sapi_name() === 'cli' )
	{
		return true;
	}

	if ( array_key_exists('SHELL', $_ENV) ) {
		return true;
	}

	if ( empty($_SERVER['REMOTE_ADDR']) and !isset($_SERVER['HTTP_USER_AGENT']) and count($_SERVER['argv']) > 0)
	{
		return true;
	}

	if ( !array_key_exists('REQUEST_METHOD', $_SERVER) )
	{
		return true;
	}

	return false;
}