jianfang@jianfang-K42JZ:~$ sudo umount $LFS/dev/pts
jianfang@jianfang-K42JZ:~$ sudo umount $LFS/dev/shm
jianfang@jianfang-K42JZ:~$ sudo umount $LFS/proc
jianfang@jianfang-K42JZ:~$ sudo umount $LFS/sys
jianfang@jianfang-K42JZ:~$ sudo umount $LFS
umount: /mnt/lfs: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))
jianfang@jianfang-K42JZ:~$ umount $LFS/dev
umount: /mnt/lfs/dev 不在 fstab 中 (而且你不是 root)
jianfang@jianfang-K42JZ:~$ sudo umount $LFS/dev
jianfang@jianfang-K42JZ:~$ sudo umount $LFS