[小技巧] NFS mount 后无法 unmount 问题解决

问题：umount 时发生如下错误：

$ sudo umount /mnt/

/mnt was not found in /proc/mounts

/mnt was not found in /proc/mounts

解决：

umount 时使用 -l 命令。

$ sudo umount -l /mnt/

参考：

man umount:

       -l     Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to
              the filesystem as soon as it is not busy anymore.  (Requires kernel 2.4.11 or later.)

https://access.redhat.com/solutions/204423