我尝试使用 Ubuntu 修复我的硬盘，但遇到错误消息并且不知道如何继续。我需要修复坏道
fsck /dev/sdb
fsck from util-linux 2.20.1
e2fsck 1.42.5 (29-Jul-2012)
fsck.ext2: Permission denied while trying to open /dev/sdb
You must have r/w access to the filesystem or be root