I do
$ df -h
...
/dev/sdc1 1,5G 1,5G 0 100% /media/username/Ubuntu 17.04 amd64
$ umount /dev/sdc1
$ df -h
...
#sdc1 now not listed
$ sudo dd if=./memtest86-usb.img of=sdc
307200+0 records in
307200+0 records out
157286400 bytes (157 MB, 150 MiB) copied, 2,78627 s, 56,5 MB/s
but flashdrive remain unchanged.
what is wrong?
df
only lists mounted partitions, so of course it would not show up in the output after unmounting.bs=4M
. Also makesdd
run a bit faster, iircdd
commands. That you make a mistake at all is an indication that you are not givingdd
the respect it deserves. There's a reason seasoned *nix folks call itdisk destroyer
.