Please explaiin disk permissions

Can someone please explain to me what repairing disk permissions actually does. I have seen (and followed) this advice on quite a few occasions - normally before and after updating/installing new software. No real clue why though!

On a separate - though possibly related point - I run Cubase SX3, and after installing it found that if I clicked on help there were no help files there. I have since found them through HD/library/documents/steinberg, but when I click on them I get a info window telling me that I don't have permission to view them. I'm the administrator - surely I should have permission to see everything on my computer.

Any thoughts gratefully received

Zim

 

Every Mac file has a set of permissions that sets limits on who can open it, edit it, and possibly execute it. When you install new software, a receipt is stored in /Macintosh HD/Library/Receipts. This receipt includes the proper permissions settings for the new software. When you repair permissions, the OS restores the permissions of each file to the setting listed in its receipt file.