Can't repair disk permissions on external drives?

Open /Applications/Utilities/Terminal. (If your account is not an admin account, first make it one, in >System Preferences...>Accounts>ACCOUNT NAME. It will require logging out and logging in again. You can remove the admin ability when you're done, if you want.)
Copy the following blue text in to a text file, then replace VOLUME NAME with the name of the drive you are having problems with, but LEAVE THE QUOTATION MARKS. Next copy it into Terminal, press enter, and type your password. You won't see any indication of typing anything for your password, which is normal.
sudo chown -R `id -un`:`id-gn` /Volumes/"VOLUME NAME"

Next, repeat the copy/paste procedure, with this blue code:
chmod -R 755 /Volumes/"VOLUME NAME"


That should fix your problems with the external drive.

Good luck!

You can only repair permissions on drives that have OS X installed on them-that is repair permission's only purpose in life-to fix problems with OS X system file permissions. On drives without OS X on them, you can set permissions to whatever you want without any problem (as long as you can read+write 😉 )

Good luck!

The repair permissions option is only available on a drive with a bootable Mac OS X system installed. A Time Machine backup is not directly bootable.

(30087)

I am 17 laptop/titniu,, 1.33 hz, 10.4.11 - I believe I may have inadvertently changed my externals hardrive permission/access to no permission/no access. I was checking this out thuis feature and the chioces for writwe/read ect etc and got a phone right while I was doing this...got distracted and 30 minutes later I had to leave so I shut down my comp and when I started up the drive when I got back the drive did not appear on desk top but upon using the disk utilities i can "see" it is read by the utility but when attempting to reset or change I was not able to get the drive to be highlighted to be selected.

Sorry if this is a newbie error and has a simple solution at wits end with work on the drive...