Formatting a Flash Drive
blinux.list at thechases.com
Thu Jan 13 12:41:18 UTC 2011
On 01/13/2011 02:10 AM, RiverWind wrote:
> I can not understand for the life of me how the flash drive
> all of a sudden became a "read only" media, let alone how to
> remedy the matter.
My first thought is that the drive is mounted under/by a
different user. If you run under the user "riverwind", and the
drive was mounted under the "root" account instead of your user
account, it would display exactly this read-only behavior.
To find out you can do the following:
This give you a list of mounted devices and where they're
mounted. You're interested in the one that's mounted where your
drive is. Usually this is something like /media/usb0 on a Debian
system, though I don't know where it ended up.
You can then go into the directory containing that mount-point
and take a listing. Assuming as mentioned above that your drive
is mounted at /media/usb0 then you want to
bash$ cd /media
bash$ ls -lFd usb0
This will do a long/wide ("-l") listing of that directory for the
mount-point. The fields of interest are the owner information
and the permissions. In a world where the drive was mounted by
your user, you should likely find "riverwind riverwind" (your
username and primary group which most distros create as your
name). However my suspicion is that you'll note "root root"
("root" is the owning username and "root" is the owning group).
That alone isn't enough to prevent you from accessing it, but
(depending on your settings) might be enough to prevent you from
writing/changing to the media (including deleting).
You can then look at the permissions column to see what
permissions that folder grants. My guess is that you'll find
"drwxr-xr-x" which means that, if it's not owned by your user,
that you (part of "other", the last 3 characters) can read files
("r") and list directory contents ("x"), but not write changes
(the penultimate character is a "-" instead of a "w").
Including the output of that "ls" command in a reply would help
if the following resolution ideas don't work.
THAT SAID. (Sorry, I tend to ramble)
To fix you need to get that drive remounted under your user. A
couple options might work for you depending on how interested you
are in the dirty details. The fastest/easiest solution might be
to shut down the computer, remove the drive, start up the
computer, log in, and then re-insert the drive. Hopefully that
will cause it to notice that you're logged in and should be the
one to "own" the drive.
Personally, I abhor rebooting, so the technical solution to that
would be to un-mount the drive as superuser:
bash$ sudo umount /media/usb0
Once that completes, you can either try re-mounting it yourself
as your non-root user:
bash$ mount /media/usb0
or if you get a "you don't have permission to mount that here"
message (per your /etc/fstab which would also be helpful to
include in an email if you're willing and still having trouble),
you can safely pull out the drive and re-insert it (hoping that
it properly detects you as the user this time instead of root).
There's a delicate interplay between your /etc/fstab file which
tells where/who/how things get mounted, and your hotplug/dbus/hal
which may try to do the auto-mounting for you. How this works
varies between distros, so I'm not sure I can help much more.
Hope this gets you further towards your goals.
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