Things Repair Permissions Will Fix
Startup issues of various sorts.
Standard folders outside of a home directory that you should be able to write to and cannot.
Network features that fail to work.
General system features that fail to work or give a “permission denied” error or sorts.
Things Repair Permissions Will Help Fix
Restoring a drive from a backup in such a way that permissions were not copied. It will not recreate hard links, symbolic links, or special files. If your backup has any files in /dev at all then it’s a bad backup and will never boot a system.
Restoring a good backup to a usable state. It will not bless it. Use the command-line tool bless for that.
Things Repair Permissions Will Not Fix
Anything involving software that was not installed with the computer or with an installer other than Apple’s Installer.
Things in home directories.
Things in folders made after installation.
Why?
Repair permissions reads the Bill of Materials in the installation receipts in /Library/Receipts that Apple’s Installer leaves after installing something. This is also why this only works on systems where Mac OS X is installed; no other volume will have these files. Since it uses them as a database of permissions settings rather than keeping them inside the program, it needs the receipt files to repair the permissions. Accordingly, if the files in the Receipts directory are removed then those files will not be repaired.
Got it from:
http://www.codepoetry.net/archives/2003/10...op_database.php