Checking and Repairing File Permissions in OS X

Beginning with Mac OS 10.2, it is now possible to check and repair file permissions for system files. All files on the Macintosh are owned by some user and have "privileges" associated with them. The privileges grant the owner, other users on the system, and guests from outside the system the ability to read, write, or delete a file. It is important for files associated with Jaguar to have the correct permissions in order to function properly. It is recommended that users repair their file permissions after installing any new system software or new applications. Some people have found their systems will run faster after repairing file permissions.

Note: Repairing file permissions may also solve problems with misbehaving applications.

To repair file permissions:

1. Double-click on the Disk Utility application, which is located in the Utilities folder inside of theApplications folder.
2. Select the hard drive containing the Mac OS X software from the list of disks which appears on the left-hand side of the Disk Utility window by clicking on it once.
3. Click on the First Aid tab in the same window.
4. After clicking on the First Aid tab, several buttons should appear in the Disk Utility window.
5. Click on the Repair Disk Permissions button.The repair process should take about 5-10 minutes, and when it's finished all the file permissions should be set to the correct values. In Mac OS 10.2.X the window will look like this:

Whereas in Mac OS 10.3.X and later it will look like this:

Note: The Repair Disk Permissions function in Mac OS 10.5.x is taking a lot longer to complete than in the past. Disk Utility will indicate that it is 1 minute from completion but often will take up to 30 minutes to finish the task. The best thing to do in this case is to let it run to completion. Doing other things on the computer while it's running will not interfere with the Repair Disk Permissions process. This problem seems to have been fixed in Mac OS 10.6.X.