How & Why to Repair Disk Permissions in OS X with Disk Utility

Jan 13, 2015 - 30 Comments

Disk Utility in Mac OS X Repairing Disk Permissions is a simple procedure that Mac users can run with the Disk Utility app or through the command line, and, as the name suggests, it repairs the permissions of various files on the target drive. Repairing permissions can be helpful when troubleshooting some fairly specific issues, or after installing or uninstalling a set of Mac applications that may have erroneously modified permissions somewhere on a drive. This is a largely misunderstood process, so we’re going to shine some light on it, and if you’re unfamiliar, how to resolve permissions issues with the repair procedure.


We’ll discuss why you may want to repair permissions in a moment, but aside from resolving some specific permission related issues with files or folders in OS X, whether user attributed or caused by modifying of removing software, the permission repair function is greatly misattributed and is rarely the panacea of troubleshooting remedies that you may see ascribed to it, though that doesn’t suggest that you should not incorporate it into part of an occasional maintenance routine for a Mac. Do keep in mind that when you’re updating OS X, the repair permissions procedure is kicked off on it’s own.

First, let’s learn how to both repair and verify disk permissions (the latter of which really isn’t necessary), and then let’s learn a bit more about the process itself and why it would even be necessary.

Repairing Disk Permissions with Disk Utility in OS X

This will repair any discrepancies in permissions found with various files and folders on the target disk connected to the Mac. You can do this with a boot volume or external drive, or both, it doesn’t matter which.

  1. Open the Disk Utility application in OS X (located in /Applications/Utilities/)
  2. Select the disk from the left side menu to repair permissions for
  3. Go to the “First Aid” tab and click the “Repair Disk Permissions” button and let the process run from start to finish – this may take a while depending on the size and speed of the hard drive

Repair Disk Permissions in Mac OS X

You will likely see multiple messages stating that various files and directories have been “Repaired” after finding differing permissions, which will look something like this:

Permissions differ on “Applications/.DS_Store”; should be -rw-rw-r– ; they are -rw-r–r–

Repaired “Applications/.DS_Store”

Group differs on “Library/Printers/PPDs/Contents/Resources”; should be 80; group is 0.

Repaired “Library/Printers/PPDs”

When finished, you will see a “Permissions repair complete” message appear in the Disk Utility console. If you have multiple hard drives or volumes attached to the Mac, you may as well run the process again on the other drive while you’re in here.

Verifying Disk Permissions on a Mac with Disk Utility

The verification process can usually be skipped, all it does is check to see if there are any improper permissions issues that can be resolved with the repair function. Nonetheless, it can be good practice to run the verify procedure anyway, but since in the repair process things will be verified anyway, we’ll cover it second:

  1. If you haven’t already, open the Disk Utility app, found in the /Applications/Utilities/ folder (or accessible through Spotlight by hitting Command+Spacebar)
  2. Select the disk in question that you wish to verify permissions for
  3. Under the “First Aid” tab, click the “Verify Disk Permissions” button and let the process run

Repairing Disk Permissions on a Mac with Disk Utility in OS X

Nearly all Mac users who run verify (or repair) will discover that some permissions are off, usually with obscure files in the temporary or Library folders, thus don’t be alarmed if you see things pop up with messages like:

“Group differs on “Library/Printers/PPDs/Contents/Resources”; should be 80; group is 0.”

“Permissions differ on “Applications/.DS_Store”; should be -rw-rw-r– ; they are -rw-r–r– “

If you do see any differing permissions, go ahead and run the Repair function next. Or you can jump straight to repair without verifying, there is no harm in doing so.

Why Repair Disk Permissions on a Mac?

Permissions for some files and folders will inevitably change, whether because a user modified the permissions of a file or folder that they shouldn’t have, or because of the installation or removal of an application or utility. Taking the latter example, sometimes installing and uninstalling an application can result in some files with specific permissions being changed from, say, only being writable by the active user to being universally writable (or not writable at all), or vice versa, thus leading to some permissions errors when that file is being accessed in the future. In most cases, these inconsistencies with specific file permissions won’t impact applications, performance, or anything else notable on the Mac, but in some relatively rare circumstances they can cause trouble, leading to either erroneous behavior in OS X. In an extreme example of a problem generated by improper permissions, the completely broken display of system fonts showing up as wild characters rather than the text you’d expect to see can be result of the system fonts folder having improper permissions and being attributed to the wrong user or group.

Because differing permissions on files or folders, either with or without consequences, is nearly guaranteed to happen over time when using a Mac and installing and uninstalling a variety of applications, repairing permissions is worthwhile on an occasional basis. Feel free to add it to the list of maintenance to perform on some semi-regular basis for a Mac, just don’t expect it to perform any miracles or speed up your Mac, that’s just not how it works.

And yes, the permissions repair process is identical in all versions of OS X with the Disk Utility app, regardless of whether the Mac is running Yosemite, Mavericks, Mountain Lion, Tiger, Leopard, or whatever else. Similarly, the process works whether you’re booted normally, in single user mode, or from a repair drive.

Enjoy this tip? Subscribe to the OSXDaily newsletter to get more of our great Apple tips, tricks, and important news delivered to your inbox! Enter your email address below:

Related articles:

Posted by: Paul Horowitz in Mac OS X, Tips & Tricks

30 Comments

» Comments RSS Feed

  1. Peter Ogden says:

    Great article, this is so misappropriated in OS X it’s hard to believe. Working in IT I heard this all the time, as if it was the defrag for Mac, oh do it on everything, why not? Repairing permissions has long been the “gargle salt water and take vitamin C” of every symptom that happens to a Mac, total rubbish that is wrongly prescribed. I’ve even seen supposedly reputable and popular sites tell you that it speeds up a Mac, LOL!!! Yea, unless your kernel has the wrong permissions, there’s no amount of chowning that is going to speed up anything.

    The Great Gruber called it “Voodoo” which is another way of putting it, it’s kind of amazing that up until this piece, nobody has pointed out all it does is change the permissions of some files back to their original state, things you would never notice and that typically cause zero issue. But research takes effort, something few want to do.

    This is why I love OSXDaily, you won’t find a more thorough Apple site.

    • mirel says:

      Since I updated to Yosemite, the bluetooth has disappeared .
      Someone told me that Repair Disck Permission will help me!
      I did it! but just like you said: Nada! Nothing! Useless!
      don’t even know what else to do…

      • Zekester says:

        Try running the Onyx utility (http://www.titanium.free.fr/onyx.html). I’ve had things disappear or the mail or wifi stop working and Onyx has fixed them. It won’t fix everything, but for the price (FREE!) it’s worth a shot. There are specific versions for each OSX release, so be sure to get the appropriate one.

        • Robert D. says:

          Some problems can be solved by clearing the caches as well. Onyx is useful for doing this. Maybe we could see an article on what the caches do (user & system cache) and how problems crop up?

  2. Robert D. says:

    Related to disc permissions, recently I was unable to update GarageBand to the latest version. When I tried to update, I got a error message that the original user was not logged into the App Store. After banging my head against the wall for a long time I finally decided to repair permissions. To my surprise, this actually fixed the problem and I was then able to update GarageBand.

  3. Shirley Allan says:

    I too had a problem with a software update to Pages. First it said it was an error and to go to the app store and try there. I did and nothing would download, it said waiting for a full day. I Repaired Permissions and the software update to Pages worked as it should.

  4. Zed says:

    I like that “gargle water and take vitamin C” analogy. It’s quick and simple, doesn’t harm anything if it isn’t the cure, and every once in awhile solves the problem well enough.

  5. Peter says:

    My permissions never seem to get repaired. I run Repair Permissions and see the list of permissions that are claimed to be repaired. Then I clear the list and run Repair Permissions again and there is the same list again. What to do next?

  6. Osc says:

    Little know fact: Disk Utility does not touch anything in your home folder when repairing permissions.

    If the issue with permissions is within your home folder, then this article has the method to do the equivalent procedure for items in your home folder: http://support.apple.com/en-us/HT203538 .

  7. Osc says:

    Peter:
    Mac OS X: Disk Utility’s Repair Disk Permissions messages that you can safely ignore
    http://support.apple.com/en-us/HT203172

    Unless something isn’t working correctly, there is no point in repairing permissions.

  8. Rosyna says:

    Repairing permissions is always useless on Mac OS X. Especially now that not a single Mac can use classic or boot Mac OS 9 or run any PowerPC programs.

    http://paradisefacade.com/blog/2013/8/7/exercises-in-futility-part-repairing-permissions-is-useless

    • nope says:

      Repairing permissions in Mac OS X is not always useless, there are situations where it is warranted as discussed in this article (and the article you link)

  9. SixnaHalfFeet says:

    Yes, rarely has repair permissions helped solve any issues, except the the occasional one like the examples of Pages and Garageband posted above.

    I wish Apple would include some really useful Disk Utility software like DiskWarrior’s abilities in the “Disk Utility” app/program. DiskWarrior can truly fix some ugly disk problems. It has saved my bacon several times resurrecting dead disks from the grave (as long as they are still spinning).

    • Tharin says:

      Hi could you please let me know how to fix copying data using diskwarrior; need to fix permissions. At the moment disk warrior preview comes with “diskwarrior the operation cannot be completed because you don’t have sufficient privileges”

  10. Ruben says:

    Peter,

    To solve this problem with repairing permissions, it is best to repair your permissions by restarting your mac’s built in repair utility (assuming you have the latest OS) by holding down the control key (or apple key) and the letter “R” (repair) simultaneously while it is booting up, this is more effective than running the disk utility while your already logged into your account. Hold these keys down for approximately 4-5 seconds, then let go. You will see a selection of options, select “disk utility and/or disk repair”. When this is selected, you will see the “disk utility ” come up at this point. Follow the same instructions as it mentioned before to repair permissions (NOTE: You might want to select in that same location, “verify disk” just to confirm the disk is ok, if it finds issues with the disk, repair it first, then repair permissions. I am an Apple Certified tech, have worked on these Macs for over 15 years. Good luck.

  11. Chuck Reti says:

    Ruben says to hold down the “control” or Apple key plus R to boot from the Recovery partition.
    You use the Command ⌘ key, which has not been an “Apple” key for a few generations of Apple keyboards. This terminology persists, but the  Apple on the key has not. Confuses the heck out of those who use newer Apple or non-Apple keyboards.

  12. Doug says:

    Why isn’t repairing disk permissions something the mac automatically does at startup, or shutdown, or just in the background while you’re working? Unless repairing permissions could somehow harm your computer, I don’t know why it’s something we have to do ourselves if it’s such a good idea.

  13. Dillon says:

    @Ruben,

    (control + R) does not get the user into Recovery mode. Huh, the Apple key, lol. It hasn’t been called that in a very long time .. its called the ( Command) key. The proper function is ” command + R “. Sure wouldn’t want u working on Mac, pfffff.

    The shape itself, which has appeared in different forms for thousands of years in Europe, may have its origins in a heraldic symbol called the Bowen knot. As a glyph, it goes by several different names including the Gorgon loop and Saint John’s Arms.

    The symbol has come to symbolize many things over the past 2,600 years or so, but it didn’t become an iconic part of computing culture until 1984.

    The story goes that when Steve Jobs first saw the keyboard command list for MacDraw he was unhappy with the number of Apple logos cluttering up the list, as the Apple symbol was used on the keyboard’s action key. He demanded that his team find a suitable symbol to replace it.
    Apple’s bitmap artist, Susan Kare, immediately began browsing for a new icon and stumbled upon the familiar symbol, which is used on modern roadside signs in Scandinavia to highlight a point of interest or cultural heritage. She presented the symbol to the team, they squealed with delight, and the Command key as we now know it was born.

  14. Dillon says:

    @Doug,

    Pls read the posted article above for your enlightenment. Pls note the following quote from Paul ….

    “Do keep in mind that when you’re updating OS X, the repair permissions procedure is kicked off on it’s own”.

    “May u live long and prosper”.

  15. MichaelG says:

    OH NO! I completed Disc repair as recommended. Now iPhoto can’t read JPG files in my iPhone. 83 of 84 pics could not be imported, were “Unreadable Files,” in “unrecognized format” (ex: IMG_5011.JPG). Only one pic was imported, format was the same for all. Now what?

    • Eerwin says:

      Permissions should have no impact on iPhone or iPhoto. Reboot the Mac into Safe Mode by holding down the Shift Key, repair permissions, and see if you can open JPG on its own. Can you open a JPEG normally from the Finder? What app does it open with? Maybe another app has taken over your JPEGs that you installed, unrelated to permissions.

      Or, it’s possible but maybe you found another new bug in OS X Yosemite, if so, contact Apple or file a report with Apple.

      • MichaelG says:

        Still using Snow Leopard. Very satisfied with performance, except for Safari/Google search downgrades (unsupported browser).
        I import files from iPhone very often, never a problem until now.
        I restarted computer prior to reading your reply, did not hold shift key. Background pic disappeared. This does not usually happen. I shut down or restart often.
        I re-attempted import of 1 previously unreadable file. it worked. I attempted to import other files again.
        24 previously unreadable files were imported, 24 remained unreadable. There is nothing unusual about these files. I have not changed anything in my routine or on my equipment except for the Disk Repair. I also have not upgraded my iPhone 4s. Have not had any problems except for loss of FaceTime.

        I did the repair on the first 2 icons in the inventory, the 1T… and the Macintosh HD that appeared below it.

        I did not repair my Time Machine back-up external HD

        Does any of this new info help? Am I to reboot again holding down the shift key? am I to attempt repair permissions again?

        I only open JPEG files from iPhoto. The files I can’t import from my iPhone can’t be opened in my computer because they can’t be imported into my computer. I can view the files in my iPhone and select the files (fingernails) to be imported from my iPhone when it is connected to my computer and iPhoto is open. If i drag a file from iPhoto to the desktop, I can open it with preview. I don’t know about opening from Finder. I have not installed any other apps in recent months or maybe years except for recommended Flash updates etc. I hope this helps.

        • Eerwin says:

          It’s possible your hard drive is failing, in which case you would want to make ample backups. Repair Disk and Repair Permissions are intended to fix problems, not create them, so if the computer drive is experiencing issues it could be indicative of the disk itself having an issue. All drives will fail eventually, if the computer and drive are quite old it is worth considering. Did Repair Disk show you errors that were fixed?

          • MichaelG says:

            Yes, many. They were missing a numeral digit or contained an extra letter or had the wrong one of either.
            The 1T disk repair contained more repairs than the Macintosh HD repair. The repairs took approximately 7 and 6 min respectively.

            The drive was recently replaced as part of a recall.

            I have shut down my computer and then started it.
            15 additional files from the first list of unreadable files were now readable.

            I don’t know if the previously unreadable file names and the (now) readable file names are still attached to the same images. Do the files get renamed? I still have 32 unreadable file names on my first list and no way to search what images they were/are. 3 of the second list of 24 unreadable files were readable after the shut down.

            It seems iPhoto assigns file names to all selected image files selected for import, then lists the files that were unable to be imported. These unreadable file designations then seem to disappear after tapping “OK”. No image remains attached to the file name. The next import attempt may re-us file names but I don’t know if it is assigned to the same image.

          • MichaelG says:

            The operation couldn’t be completed. (com.apple.ImageCaptureCore error -9912.)

            I got the above response when I tried to import an image to my desktop, my pictures and my documents, that I sent to myself in an email from my iPhone and downloaded. I can open the image in Preview.

  16. Ann says:

    Please help! I have a mid-2010 iMac and today decided to upgrade to Yosemite. How I wish I had not!

    I get the error “file system verify or repair failed”. I ran the disk utility and verify permissions. It finds lots of error but the repair button is grayed out.

    When I reboot, it goes back to the install. I am stuck in an endless loop….

    The computer was fine before this….very grateful for any advice!

    Ann

  17. Dan Lindey says:

    I did a complete backup of my macbook, os x 10.6.8. Then I did a complete erase of all data and reinstalled snow leopard. I then attempted to copy GarageBand and various GB folders back onto my macbook. However, even after running the repair and verify in disk utility, I still can’t get every folder to copy without seeing the message of not having permission. Is there a step that I’m missing?

  18. Andii says:

    Questions

    1. Is it better to use the original Install disks or repair from the Application Disk Utility ?

    2. Can we use a different Install disk or should it be the Bundled Disks or the original Install disks ?

    3.If we use the Disks does it not replace the updated permissions ?

    4. What a about File Vault on or off ?

    5. Why have Verfy but use Repair ?

    Compare ;

    A. On MacBook 2007 Partitioned HD original Installed from disks 10.4 ,updated after FileVault ,went into Darwin,said to be related to privileges and permissions~

    B.Installed 10.6 same problem on update (maybe related) ,repaired permissions on both ,10.4 no results but repaired ,but still boots in Darwin!!

Leave a Reply

 

Shop for Apple & Mac Deals on Amazon.com

Subscribe to OSXDaily

Subscribe to RSS Subscribe to Twitter Feed Follow on Facebook Subscribe to eMail Updates

Recent Posts