dolphin/single-functions/folder-size-large.php

<?php
/**
 *  dolphin. Collection of useful PHP skeletons.
 *  Copyright (C) 2019  Johannes 'Banana' Keßler
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the COMMON DEVELOPMENT AND DISTRIBUTION LICENSE
 *
 * You should have received a copy of the
 * COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0
 * along with this program.  If not, see http://www.sun.com/cddl/cddl.html
 */

/**
 * Get the folder size with a unix command.
 * Usefull when on linux only and large files
  *
 * @param string $folder Absolute path to the folder
 */
function folderSize($folder) {
	$io = popen ( '/usr/bin/du -sk ' . folder, 'r' );
	$size = fgets ( $io, 4096);
	$size = substr ( $size, 0, strpos ( $size, "\t" ) );
	pclose ( $io );
	
	return $size;	
}