用PHP来计算某个目录大小的方法

function dirsize($dir) { 
@$dh = opendir($dir); 
$size = 0; 
while ($file = @readdir($dh)) { 
if ($file != "." and $file != "..") { 
$path = $dir."/".$file; 
if (is_dir($path)) { 
$size += dirsize($path); 
} elseif (is_file($path)) { 
$size += filesize($path); 
} 
} 
} 
@closedir($dh); 
return $size; 
} 

$bb = "/var/www/lg"; 
$cc = dirsize("$bb"); 
$aa = $cc/1024/1024; 
echo $aa.MB." 
"." 
";