How to Use the Repair Disk Permissions Feature in Mac OS X

Mac Disk Utility icon

There’s a debate in the Mac community about whether Repair Disk Permissions should be performed as regular maintenance. Some users say it’s useless. Others say it might actually be dangerous to a healthy system.

If you’re comfortable running Repair Disk Permissions, let’s get down to some basics and then walk through it.

First, some background. (If you’re already familiar with what this feature does, you can skip straight to the “How to Repair Disk Permissions” section below.)

ABOUT REPAIR DISK PERMISSIONS

  • Why might you need to repair disk permissions? Your Mac may be running slowly when you’re launching certain applications or accessing multiple applications, or even accessing multiple tabs within your browser. You might have issues launching or logging into apps or accounts. Or maybe you’ve been experiencing problems with peripheral operations such as print or scan jobs.
  • Running View Disk Permissions first will scan files on your hard drive and then list those files that it recommends repairing with Repair Disk Permissions. You can use this list to see exactly what repairs are being made.
  • While it’s true that Repair Disk Permissions will only repair files that have been installed as part of Apple-originated installation files, it is also true that some third-party installations may be dependent upon some of those original files and that from time to time such repairs on any disk are necessary as routine maintenance.
  • Running Repair Disk Permissions is a first step in eliminating other system issues as the source of an issue. In other words, if the steps taken resolve the issue that brought you to use Disk Utility, then great: there is no need to troubleshoot further. Conversely, if this routine maintenance task does not resolve the original issue, then disk permissions can be quickly eliminated as the root cause.

If you’re wondering what file permissions are, Apple explains it best.

HOW TO REPAIR DISK PERMISSIONS

1. Open Finder, go to Utilities and open Disk Utility.

Selecting Disk Utility in Finder
2. In the left pane of Disk Utility, select the name of your hard drive.
Selecting hard drive in Disk Utility

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3. In the right pane (see above), make sure the First Aid tab is selected and then check Show Details to be able to view the list of files needing permissions repairs.

The processing time to verify disk permissions will vary depending upon the size of the hard drive, the number of Apple-originated files installed and the speed of the hard drive.

Disk Utility will display an approximation of time and a progress bar.

Verifying disk permissions in Disk Utility

Note: You may safely click Stop Permission Verify at any time.

The Disk Utility will display a notice when it has completed permissions verification.

Permissions verification completed in Disk Utility

4. Now it’s time to repair. Click on Repair Disk Permissions.

Selecting Repair Disk Permissions in Disk Utility

Again, the utility will display an estimated time of completion and a progress bar.

Permissions repair in progress in Disk Utility

Note: You may safely click Stop Permission Repair at any time.

Disk Utility will notify you when permissions repair is complete.

Permissions repair completed in Disk Utility

5. After performing these system operations, it’s a good idea to reboot your Mac.
6. If you do receive Repair Permissions errors, need to modify permissions or perform troubleshooting, use this Apple Knowledge Base article.

TIPS

At any time between operations, you can view the Disk Utility Log, located in the upper right-hand corner.

Disk Utility Log icon

  • Within the Disk Utility Log you can perform a Word Search to find a particular filename and its associated information that you can copy and paste into an email to share with tech support.
  • To permanently highlight specific text in the Disk Utility Log, highlight the text and click Mark.
    Marking text in Disk Utility log

  • You can also Reload the log up to a specific file size.

Reloading Disk Utility log to specific file size

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