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Verify and repair permissions

OS X incorporates a subsystem based on a UNIX–style operating system. In this kind of system, every file and folder on your hard disk has an associated set of permissions that determines who can read, write to, or execute it.

Many things you install in OS X are installed from package files (.pkg ). Each time something is installed from a package, a file (.bom) is stored in a folder of the system or in a receipt file (.pkg). Each of those .bom files contains a list of the files installed by that package, and the correct permissions for every file. When you use OnyX to verify and repair disk permissions, it reviews every .bom file and compares its list to the actual permissions of each listed file. If the permissions differ, OnyX corrects the difference. If you remove receipts or .bom files from /Library/Receipts/, the files installed by the packages can neither be verified nor repaired. This is why you should not delete things from /Library/Receipts/.

Repairing permissions is the first thing to do as soon as you notice any issues with apps opening, file access issues, or your computer seems to be running unusually slow.

The ACLs (Access Control Lists) are an additional method to grant specific permissions to certain users. The conventional rules for access rights still apply, but some optional new rules can be added. It is a list of individual rights which can be attached to a file or a folder, and apply only to your home folder and its contents.

Repairing ACLs can solve conflicts inherited from an earlier Mac OS X 10.5 or 10.6 installation, such as the Finder always asking for your password when you try to delete, move, or copy a file.

To reset the ACL of other users experiencing an issue, go to the OnyX Preferences, select the Behavior tab, and select the "All Users" option.

To repair the permissions:

1

Open OnyX. It will ask for your administrator password.

2

Open the Maintenance pane, and click the Permissions tab.

3

If you want to reset the ACLs and permissions of your home folder, select the appropriate box.

4

Click the Execute button.

After the repair is completed, the result will appear in the text field present for this purpose. Generally, alerts that appear are only informational messages. Incorrect permissions that were not repaired will have no consequence on the functioning of your computer.

• Messages that you can safely ignore

You can use the Automation pane to repair permissions, but the result will not appear.