How do I Verify/ Repair Disk Permissions in Mac/ OS X?
What does Verify/ Repair Disk Permissions do?
Where can I learn more about Verify/ Repair Disk Permissions (and Unix file permissions) in Mac/ OS X?
Repairing disk permissions on your Mac can resolve issues with specific programs and files. Repairing Disk Permissions may seem like a routine, mundane troubleshooting step, but it can provide valuable information on an issue--or even resolve the issue altogether, and it is a good preventive maintenance tool for your Mac.
How do I verify/ repair disk permissions?
To verify/ repair disk permissions, follow these steps:
Launch Disk Utility. By default, Disk Utility is stored in the Utilities folder (within your Mac’s Applications folder). You should also be able to launch it by searching for Disk Utility in Spotlight.
In the source list (in the pane that appears on the left-hand side of the Disk Utility window), select your Mac’s startup disk.
Click the Repair Disk Permissions button. The button should appear underneath the large white text box in the middle of the Disk Utility window (on the left-hand side of the box). Verify Disk Permissions could take a few minutes.
It is recommend that you quit all apps but Disk Utility before repairing permissions.
Frequently Asked Questions
How does verify/ repair disk permissions work?
For every program installed on your Mac that installed with a .PKG installer program, a specific type of log file (called a bill of materials) is kept, to keep track of which file access permissions specific files related to the program should have. Verify/ Repair Disk Permissions checks values listed in bill of material files and changes file permissions for files in your library based on information it finds in bill of materials files.
Programs purchased through the Mac App Store are also installed via .PKG installer.
What are file permissions, and why are they important?
Every file on a Unix filesystem has specific file access permissions. Unix file permissions are a set of rules that specify which users are allowed to view, write, and execute the contents of a file or folder. Permissions are set for a file’s owner, owner group, and for all users on the computer. Mac/ OS X also uses a set of extended file permission attributes, which specifies additional access privileges.
If a program does not have the correct permission to access to a file it normally uses, the program might not function as expected. Depending on which program is not functioning as expected (and which other programs depend on it), unpredictable behavior in one program can cause unexpected behavior in others.
What about the Verify Disk/ Repair Disk buttons (on the right-hand side of the Disk Utility window): should I use them, too?
Verify Disk/ Repair Disk perform a different set of operations than Verify/ Repair Disk Permissions. They are not needed to verify and repair disk permissions, and we do not recommend them to verify/ repair disk permissions. Use these options at your own discretion.
Does verify/ repair permissions check the permissions of every file on my Mac?
No. Verify/ repair permissions only verifies permissions on files that:
Were placed on your Mac when installing an application with a .PKG installer program.
Appear in bill of material files on your Mac.
If a file was not created when installing a program and it does not appear in a bill of material file, it will not be checked with Verify/ Repair Disk Permissions.
Where can I find more information on Verify/ Repair Disk Permissions?
For more information on Verify/ Repair Disk Permissions, we recommend this Apple knowledge base article:
For more information on Unix file permissions in Mac/ OS X, we recommend this Apple knowledge base article: