Ioannis Vranos wrote:
>
>> in above example you will need to unmount /mnt/sysimage/boot
>> before unmounting /mnt.sysimage
> 
> 
> I unmounted both /mnt/sysimage/boot and /mnt/sysimage/dev, leaving no 
> mount "below" /mnt/sysimage, but still /mnt/sysimage refuses to unmount.

I realise this isn't a direct solution to your problem.
If you need to fsck a filesystem on a machine which you cannot boot 
properly, I would suggest booting via a CD such as Knoppix.
Or use a bootable USB stick - I now carry one round with me, which is 
very convenient.

If you would rather do this without using a physical CD, you can have a 
network-bootable Knoppix.


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