Hi All, I've got a USB mem stick that seems to be dodgy, but I'm not sure. I =know= it's not worth the time and effort financially, but I'd like to be sure it's the stick, and not some other part of the system. On this web page... superuser.com/questions/376274/check-the-physical-health-of-a-usb-stick-in-linux Someone suggested using this command... sudo badblocks -w -s -o usbstick.log /dev/sdz ... where sdz is substituted for the actual device. But, when I try the command with the stick unmounted, I get an error message to this effect... No such file or directory while trying to determine device size. And, when I try the command with the stick mounted, I get an error message to this effect... /dev/sdb is apparently in use by the system. It is not safe to use badblocks! What's the obvious escape from this Catch-22 that I don't see? Thanks. Carl Bayswater