当我尝试fsck在 Ubuntu 18.04 恢复模式上运行时，我收到以下消息。谁能告诉我为什么？
/lib/recocery-mode/recovery-menu: line 80: /etc/default/rcS: No such file or directory
fsck from util-linux 2.31.1
/dev/sda4 is mounted
e2fsck: Cannot continue, aborting.