Not all that long ago, I laid out directions for doing a Permissions Repair of Mac OS X Snow Leopard. With Lion, Apple introduced Full Disk Encryption (FDE), which makes the process slightly more complicated.
Of course, you can still open Disk Utility (in the Utilities folder in Applications), and choose to Repair Disk Permissions that way. It works well, and isn’t a bad way to do routine maintenance once a week or so, but it doesn’t fix every one of the various permissions errors that crop up through normal use.
That’s because running Repair Disk Permissions from *inside* the booted OS will mean that some permissions cannot be altered (the files are in use, locked, etc.). Again, normally, this isn’t an issue, as those permissions won’t cause slowdowns or hiccups under normal circumstances.
But what happens if you notice that your Mac is acting slower than usual, apps are malfunctioning, etc.? First, check the usual suspects. Does the app need to be reinstalled? Will a reboot (first unchecking the window persistence checkbox) fix the problem? If not, then you should do a full permission repair.
First, print out this post, because you’re going to have to boot into Recovery Mode, and that means you won’t be able to get online to read the rest of the instructions.
Next, reboot your Mac, holding down the CMD and R keys from the moment the system starts (you hear the start-up BONG sound) until you see the status spinner on the white-background startup screen. Once you see the spinner, let go of the CMD and R keys.
This will boot you into Recovery Mode. If you have FDE enabled, it will also ask you to unlock the volume with your usual password. You’ll then see the spinner again, and within a few moments the Recovery Options wizard will pop up. Choose Disk Utilities and click Continue.
Once Disk Utilities is open, and if you’re using FDE, go to File in the Menu Bar and select Unlock Disk diskname – where diskname is the name of the hard drive that contains your Mac OS system. You will need to provide your normal Administrator password to unlock the volume.
In the Disk Utilities window, click on the disk/partition where Mac OS is installed (not the physical volume name, just the partition name) and then click Repair File Permissions in the lower portion of the right-hand window. After that, all you need to do is wait.
You will nearly always see several permissions being fixed, this is perfectly normal and does not indicate that anything bad or malicious has been going on. Normal OS operations occasionally cause permissions to get set incorrectly, and this process fixes those errors.
Once the process is done, you can simply restart your machine from the Apple Menu and boot up normally.
You’ll find that a permissions repair can help to correct a lot of strange issues that you might be seeing on your Mac, so doing this once a month or so is not a bad idea at all.
One important note, I have found that using a 3rd-Party keyboard is not a good idea for this process. My keyboard (a Microsoft Natural Keyboard) doesn’t seem to be recognized by Mac OS when a boot is happening, so I can’t hold down CMD and R. Any of the Apple keyboards (bluetooth and wired alike) seem to work just fine, so I keep one handy just in case.