kmosx: Repair Permissions and Repair Privileges Common Questions

Repair Permissions and Repair Privileges Common Questions

There are many posts dealing with the "Repair Permissions" option of Disk Utility (under 10.2 and higher) or the "Repair Privileges" utility (downloadable – for 10.1.5 only). This FAQ is an attempt to clarify some misunderstandings that commonly arise. Readers are assumed to be familiar with Mac OS X: Troubleshooting Permissions Issues.

I. How often should I Repair Permissions?

You do not need to Repair Permissions on a regular basis.

There are only three occasions you need to do this:

1. When you have just installed something that required you to run an Installer, rather than just copying some software to a folder. This should be done for both Apple and non-Apple software.
2. 
   
3. When you have been working on your OS X files or folders while booted from OS 9, or remotely connected via a non-OS X machine, since OS 9 and other systems do not handle OS X's permissions correctly.
4. 
   
5. The other case is if your system is behaving strangely, when you should run Disk Repair from your CD followed by Repair Permissions. This is just to eliminate these things before going on to further trouble-shooting.

Otherwise you can happily forget about Permissions!

II. Should I run Repair Permissions from my Hard Disk or from my CD?

(This of course applies to 10.2.x only, since in 10.1.5 you have no choice.)

For the most part, 'Repair Permissions' is driven by the contents of the /Library/Receipts folder, so it does not matter very much whether you run it from CD or from the HD. However in some point updates, so-called "Special Permissions" have been introduced, and these are not available to the CD version, so once these appear it is preferable to run it from your hard disk. Obviously using the HD is normally more convenient.

Note that is one very good reason why you should not delete the contents of /Library/Receipts. Under 10.3 and higher, doing this will give the error message:
Error: No valid packages (-9997).

The other reason, of course, is that Software Update uses the information in this folder to let you know if you need to update your software.

III. Repair Permissions repeatedly gives me the Same Errors

There are a number of spurious error messages issued by the Repair Permissions utility. These are listed in the accompanying FAQs: Spurious Permissions errors in 10.2, Spurious Permission errs in OS X 10.3, and Permission Messages in OS X 10.4. Some are documented in the Knowledge base, in which case a link is given to the relevant article.

IV. "Operation not Permitted" message

See MarkDouma®'s FAQ: kmosx: Repair permsissions: Operation not permitted, or run Repair Permissions from your CD rather than the hard disk, then, if necessary run it again from the hard disk.