I can't format a USB stick

lucmove · 10-25-2021, 08:31 PM

In fact, I want to write an ISO image to it. But bear with me.

I insert the USB stick and it automounts to /dev/sdc1.

I don't want those contents anymore. I am ready to overwrite it all.

I umount /dev/sdc1.

Code:

# dd if=/image.iso of=/dev/sdc
dd: failed to open '/dev/sdc': No medium found

I reinsert the USB stick.
It automounts to /dev/sdc1.
I umount /dev/sdc1.

Code:

# dd if=/image.iso of=/dev/sdc
dd: failed to open '/dev/sdc': No medium found

I'm stuck.

frankbell · 10-25-2021, 08:36 PM

This is a shot in the dark, but . . . .

/dev/sdc is the device.

/dev/sdc1 is the partition containing the files on the device.

Try pointing your command a /dev/sdc1.

lucmove · 10-25-2021, 08:43 PM

Thanks, but no. An image must be written to the device. I've done that many times over the years.

For example,
https://www.system-rescue.org/Instal...-memory-stick/

jefro · 10-25-2021, 09:10 PM

Try mount command just to check if something else is going on or use Gparted/Disks.

Try sudo but that should reply a permission issue.

lucmove · 10-25-2021, 09:32 PM

I've finally made it.

Insert the stick and let it automount. Whatever.
Run cfdisk /dev/sdc
Delete all partitions and write changes.
Remove and reinsert stick.
Run cfdisk /dev/sdc again, create one Linux partition and write changes.
Run dd to write the image.
Wait until it finishes.
The stick will automount again. Whatever.
Shake head in disgust.
Unmount /dev/sdc1 and /dev/sdc2 (yes, I had both. go figure)
Remove the stick.

mrmazda · 10-25-2021, 11:29 PM

If a USB stick has a LABELs on its filesystems, for each that has an entry in fstab, with a noauto option, that filesystem won't be automounted. You can use that same set of LABELs for as many sticks as you please, and none will automount.

To eliminate the content of a stick, you don't need a partitioner. Simply use dd to write nonsense, nulls or zeros to the first sector(s). After removal, there won't be any filesystems to automount on next insertion.

ondoho · 10-25-2021, 11:48 PM

Quote:

Originally Posted by lucmove

automounts
(...)
automounts

Quote:

Originally Posted by lucmove

automount
(...)
automount

The joys of "user friendly" desktop environments.

Shot in the dark(*): if you use the GUI to unmount, maybe it also "eject"s the USB. Then it doesn't show up under /dev anymore.

(*) your descriptions show your frustration but not much information.

pan64 · 10-26-2021, 03:30 AM

you ought to switch off that automounter in such cases.

computersavvy · 10-28-2021, 03:39 PM

Quote:

Originally Posted by ondoho

The joys of "user friendly" desktop environments.

Shot in the dark(*): if you use the GUI to unmount, maybe it also "eject"s the USB. Then it doesn't show up under /dev anymore.

(*) your descriptions show your frustration but not much information.

Nautilus on fedora does exactly that. It both dismounts the file systems and ejects the device.

In order to use dd and write the iso to the usb drive it is necessary, from the command line, to check what is mounted, use umount to unmount the partition(s) from the usb device that may have automounted, then use dd to write the iso to the device. Partitions created do not automount again until the device is unplugged and plugged back in.