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Old 11-16-2010, 05:42 PM   #1
mjhera
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Registered: Oct 2010
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USB Devices read-only in Maverick


Hi there, I have a 7 port USB hub that is connected to my Dell GX260 that was working perfectly until the other day. I have Maverick running on the pc and before that Lucid. I had no problems read/writing to USB Flash drives that were plugged into the hub. Now I can only write to them through Nautilus (root), otherwise it tells me 'permission denied'. Any help would be appreciated. I have 4 other ports on the pc and they have the same outcome.

Michael.
 
Old 11-16-2010, 07:43 PM   #2
frankbell
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I have had USB devices (usually my podplayer) go to read only for no good reason that I could figure out.

Usually, unmounting the device, removing it, and then reconnecting it has given control back to user.

While the problem exists, you might try opening a terminal and running "sudo dmesg," then capturing the relevant output to a text file, then doing the same while the problem does not exist, and comparing the two.

Back in the olden days, when Linux plug and play was not so far advanced, I used to put USB devices in my fstab with "noauto,user,rw" variables.
 
Old 11-16-2010, 10:56 PM   #3
mjhera
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Hi frankbell, thanks for responding.The problem is an ongoing one so until I sort it I won't be able to see the difference. Although it may be no harm to see what dmesg outputs at the moment, I also might mention that I have a wireless keyboard and a usb mouse attached and they work fine. The thing is that I usually have 3 or 4 usb flash cards plugged in and none of them now let me write to them unless I do so using Nautilus. Thanks, Michael.

Last edited by mjhera; 11-16-2010 at 11:03 PM.
 
Old 11-17-2010, 09:14 PM   #4
frankbell
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No answers, but a couple fo thoughts for testing:

Try coping a file to them using cp from a command line and note what error message you get.

Also, assuming they mount in /media, cd to /media (or wherever they exist) and run ls -l and see what it tells you about the permissions and ownership.
 
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Old 11-17-2010, 10:03 PM   #5
mjhera
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Hi again frankbell, I tried out what you suggested there and on my laptop with maverick it gives me -
'drwx------ 18 michael michael 8192 1970-01-01 01:00 PS3 USB' and on my desktop it gives me -
'drwxr-xr-x 12 root root 8192 1970-01-01 01:00 USB1'
That is with the same USB Flash drive.

The other part using cp to copy gave me this -
"Error opening file '/media/usb1/autorun.conf':Permission denied"

This is a bit above my ubuntu experience level! Anymore ideas would be very welcome. Thanks, Michael.

Last edited by mjhera; 11-17-2010 at 10:07 PM.
 
Old 11-18-2010, 09:59 PM   #6
mjhera
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Hi all, I may have stumbled across a solution for my problem, via synaptic packet manager I uninstalled PMOUNT and USBMOUNT (which also took ubuntu-rescue-remix with it) and voila - all my usb flash drives have returned to read/write with user permissions. I have shutdown and restarted a few times to make sure it wasn't a once off. I also checked permissions as was suggested by frankbell and all are ok.

Thank you frankbell for your input and time, you put me on the right track!

Michael.
 
Old 11-18-2010, 10:06 PM   #7
frankbell
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The first line means that root owns the drive and only root can execute it (if it's executable) and only root can copy a file to it.

There's a good pretty clear explanation of Linux permissions here:

http://www.linuxforums.org/articles/...ssions_94.html

In my limited experience, you can get this if the device is mounted under root authority. Root mounted it, therefore it is root's.

If the devices are in your /etc/fstab file (good explanation here), edit the fstab so that ownership belongs to user:

For example (this is for my external USB connected SATA drive on this Debian box):

Code:
/dev/sdb1       /media/sdb1     ext3    auto,user,rw       0       0
instead of this:

Code:
/dev/sdb1       /media/sdb1     ext3    auto,root,rw       0       0
If it's not in your fstab, try unmounting it or ejecting it as root, the remounting it as user and run the ls commands to see whether anything has changed.

I have had this happen two or three times to the external harddrive I use with my Ubuntu computer. Usually, ejecting it, disconnecting it, and then reconnecting it clears up the problem, but it's been too random for me to figure out what causes it.
 
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Old 11-18-2010, 10:16 PM   #8
mjhera
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Registered: Oct 2010
Location: Sligo, Ireland
Distribution: Ubuntu 10.10
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Hi frankbell, i'm learning alot about ubuntu since I first installed 10.04 last june but what I would say is I have alot more to learn! Its good to know that help is always a few clicks away and thanks to yourself and others its far more enjoyable to learn to use ubuntu and have that rush when you solve a problem!!

Thanks again for your time and effort.

p.s. ive learned alot about how usb works!!

Michael.
 
  


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