or download this
sub __NR_statfs () { 99 }; $file = "/"; $s = pack "x256"; -1 == syscal
+l(__NR_statfs, "".$file, $s) and die "error statfs: $!"; (undef, $bsi
+ze, undef, $bfree, $bavail) = unpack "l!5", $s; print $bavail*$bsize/
+1024, " kilobytes available\n";