Devuan Daedalus 5.0 on AMD 64
Xfce desktop

Hi All:

I accidentally disconnected my Ext2 USB HDD. I need to run fsck on
it. Howeverwhne I I plug iit in , Thunar mounts it. If I unmount it,
then the /de/sdb4 disappears.

How do you fsck a corrupted external HDD? Is there a way to turn off automount?

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Kind regards,
Jonathan