When it comes to keeping your Mac running smoothly, repairing permissions is one of the quickest and simplest tasks to do for a user switching to Mac. Permissions are the term Mac OS X uses for the access privileges a user has for every file, folder and application on their system, giving that user the permission to read from, write to or execute that particular item.
A quick way to look at the permissions for a particular file is to Right-Click on it, select Get Info, then click on the arrow next to Sharing & Permissions:
As you can see, the user has Read & Write permissions for this document, but Staff and Everyone can only Read it, and not modify it.
Permissions are essential for your Mac to function correctly. Generally OS X automatically ensures that permissions are set correctly, but sometimes, especially after installing new software, either from a disk or Software Update, the permissions can be set incorrectly. In worst case scenarios, this can affect your ability to even open a file or launch an application.
While you can use a third-party application such as Onyx to automatically repair permissions as part of your general Mac maintenance routine, for quick permission repair OS X’s in-built maintenance application Disk Utility is the simplest option.
1.) Go to Applications then Utilities and open Disk Utility to launch the program. You will be presented with this interface:
2.) Select your Mac’s main hard drive (generally named “Macintosh HD”) from the left-hand pane:
3.) You will be presented with the following screen with various disk maintenance options:
4.) In this scenario, we are interested in the First Aid tab that initially opens, so remain there. There are two options pertaining to permissions on this tab – Verify Disk Permissions and Repair Disk Permissions. Verify Disk Permissions will check through the selected hard drive’s access privileges, flagging any possible conflicts but not repairing them.
It can be useful if you are simply troubleshooting an issue. However, in this case we wish to go straight to repairing the privileges, so click on the Repair Disk Permissions button:
5.) Disk Utility will now proceed to begin repairing permissions. A blue bar will initially appear in the bottom right of the interface, which will turn into a timer once Disk Utility has estimated how long the procedure will take:
6.) The process may take some time dependent on when a repair was last run and what files have been installed since that repair. When Disk Utility is finished, it will report “Permissions repair complete” at the bottom of the central pane:
Disk Utility is a very useful application for Mac users, allowing for all manner of disk maintenance activities from formatting USB drives to repairing damaged hard drive sectors, and is comparable to commercial software that would cost you a significant amount on the Windows platform in the depth of it’s feature set, yet is bundled for free with every copy of OS X.