[lucid] how to mount USB storage with correct permissions?

[Reinhold Rumberger]

On Wednesday 27 October 2010, D. R. Evans wrote:
> I have been unable to access USB devices under lucid, but it
> wasn't important enough for me to bother with the problem until
> today.
> 
> After some googling I came across this thread:
>   http://newyork.ubuntuforums.org/showthread.php?t=1470705&page=4
> 
> which told me to install usbmount, which (at last) allows me to
> mount USB drives so that I can see their contents.
> 
> But the drives are marked as being owned by root, so I can't write
> to them.

Actually, that's not true - they should be owned by user root and 
group disk. Then, any user in the disk group can write to them. 
Here's what the listing looks like on my machine:
brw-rw---- 1 root disk 8, 16 2010-10-28 00:15 /dev/sdb
brw-rw---- 1 root disk 8, 17 2010-10-28 00:15 /dev/sdb1
brw-rw---- 1 root disk 8, 32 2010-10-28 06:15 /dev/sdc
brw-rw---- 1 root disk 8, 33 2010-10-28 06:15 /dev/sdc1
brw-rw---- 1 root disk 8, 48 2010-10-28 00:15 /dev/sdd
brw-rw---- 1 root disk 8, 49 2010-10-28 00:15 /dev/sdd1

> I tried changing the permissions on /dev/usb and /dev/usb0,

What are those two supposed to be? They don't even exist here.

> but as
> soon as a drive is actually mounted, the permissions change back
> so that only root is allowed to write to the drive.

Are they, perhaps, links to the actual device files? If so, the 
permissions of the links are without consequence.

> What do I have to do so that when I insert a USB drive into a USB
> port I can, as an ordinary user, both read and write to the
> drive.

Usually just make sure the user is in the disk group. (In the user 
management module in system settings, make sure the user has the 
"Access external storage devices automatically" privileges checked.)

There's also the possibility, when using "native" file systems like 
ext2/3/4, that the permissions are stored on the file systems. Simply 
change them the way you would normally
 (sudo chown [-R] <user> <file>).

  --Reinhold