Random script that I hacked together to enable removal of packages from the (currently) little documented file /Library/Receipts/db/a.receiptdb in Mac OS X 10.5 Leopard. From my brief exploration, a.receiptdb seems to be new to Leopard and is used in addition to /Library/Receipts to keep metadata on what programs have been installed via pkg/mpkg.

This script will be useful for anyone (like me) who is trying to reinstall "Optional Installs" (such as drivers) from a Leopard DVD that is newer than the original DVD they used. If you try doing this, components that were previously installed will be greyed out.

A random person by the name of Emil emailed to point out the following. 'I haven't tried it myself, but I think what you are trying to do can also be accomplished using the "--forget" and/or "--unlink" flags of the command pkgutil.' I have not tried this either (since my script did what I needed to do), but I hope this helps someone! Thanks Emil!