The rights and wrongs of installing
We recommend that you should learn the safe way of installing and you should always make sure that you can back out of an installation, but how exactly do you do that? There are seven stages to a successful update, or indeed for installing a new product.
1. Take an image of your system as it is now
Apple’s Disk Utility enables you to make an exact copy of your hard drive as either a bootable copy on another hard drive or as an image file that can be saved on any volume such as a drive or a server.
Taking an image of your system before you start to work on it means that you can always go back to a known working state if things go wrong with the update. Restoring an image is far faster than wiping the hard drive and installing everything from scratch or trying to undo whatever the update just did.
2. Repair privileges
Disk Utility can also check that things on your drive are as they should be, making sure that file privileges for certain items are correct. It is important to make sure that things are as they should be before you start to make changes.
3. Clean caches and run maintenance routines
Delete the folders ~/Library/Caches and /Library/Caches. Run the periodic routines which usually run every night. These give your system a minor “tune-up” before you start the installation. To force them to run when you want them to open Terminal and issue the following commands:
sudo periodic dailysudo periodic weekly
sudo periodic monthly
Repairing privileges, clearing caches and running maintenance routines will fix any minor problems that you may not have been aware or and will ensure that the caches will be created afresh taking the update into account rather than risk using any old data.
4. Disconnect all FireWire devices
This is particularly important when installing OS updates and has been known to cause problems if not done.
5. Install the update or program
6. Repair privileges again
7. Leave things where the installer put them
Some programs, particularly Apple ones, will not update properly if they are not in the same place that they were installed, or you may have problems with the application not being able to find required support files. e.g. if you put iTunes into a sub-folder of your Applications folder called Music then there have been reports that Apple installer will not be able to update it. If you want to have your applications in another folder then create an alias of the application and then put that into the folder concerned.
Isn’t there an easier way?
Yes there is, you can do all of the above without having to go into the command line or remember which cache folders to delete.
Carbon Copy Cloner is a great way of making images of your system and is a lot friendlier than using Disk Utility.
http://www.bombich.com/software/ccc.html
Two utilities, Xupport and Cocktail, enable you to clean out your caches, run maintenance routines, optimise your system and repair privileges without you having to go anywhere near the command line.