Read Only usb stick that won't let me do anything to it

Question

Somehow I messed up and accidentally made my usb stick into a read only file system. I have tried a bunch of things to delete the files, including the basic (rm -f myfile) and attempting to allow writing (sudo chmod +w myfile) and then deleting, but none of this seems to work. Any ideas on what I can do. I don't have anything on the usb stick that I need, but I don't want to throw away an otherwise perfectly good piece of equipment.

How can I make it work? Am I going about this completely the wrong way?

Answer 1

Commands like rm and chmod are done on a mounted file-system. So if the file-system is read only those do not work. What you need to do is to mount the file-system as writeable.

Some USB sticks have a switch on the stick to mount them read-only. Maybe that is the reason. It could also just be broken or damaged due to not correctly umounting it.

Before you do anything: copy the files over from the stick.

If it is not a hardware switch unplug and plug the USB stick and issue a

dmesg | grep -i panic

This will show you any panic messages. If you are seeing alot of them related to the USB stick and if it is a FAT partition you can use dosfsck to fix it.

You can find out how it is mounted with

mount

and use

dosfsck -a /dev/sd{xn}

to fix an MS-DOS partition table or sudo mkfs.vfat to format the disc. Where {xn} is a letter and digit you got with the mount command.

You can also use gparted to format it by the way.

Answer 2

Yes, if the filesystem is read-only, then setting modes on files will not have any effect at all. You can see in /etc/fstab if the filesystem is mounted read-only. But if you don't have anything on it, then you can also just make a new filesystem for it in gparted or palimpsest (the latter is installed by default in Ubuntu and is called Disk Manager or something).