why is RW-mounted SD card treated as mounted RO?

[Nils Kassube]

Robert P. J. Day wrote:
>   perhaps a simple solution to this, but i tossed an SD card into my
> ubuntu 10.04 laptop, whereupon:
> 
> $ mount
> ... snip ...
> /dev/sdb1 on /media/6458-0D98 type vfat
> (rw,nosuid,nodev,uhelper=udisks,uid=1000,gid=1000,shortname=mixed,dma
> sk=0077,utf8=1,flush) $
> 
>   that normally suggests that the card is mounted read/write, but if
> i "cd" onto the card and attempt to make any changes, i get:
> 
> $ touch fred
> touch: cannot touch `fred': Read-only file system
> $
> 
>   am i overlooking something obvious?  the SD card is unlocked, the
> mount comment certainly suggests that the filesystem is writable, but
> any attempt to modify the card contents fails (sudo makes no
> difference, and that would generate a "permission denied" error,
> anyway).

Maybe you should check the filesystem. Unmount the it and then run

sudo dosfsck /dev/sdb1

in a terminal. See "man dosfsck" for more options.


Nils