Kill the Cache

March 12, 2004

In Mac OS X, one of the best things you can do when having strange problems with apps quitting and generally behaving badly is trashing the cache. This is easy in Panther, but because of the way privileges work, more difficult in Jaguar or earlier.

Cache affects just about everything, from preview icons in Finder, to cached web pages in Safari, from iChat pictures to Mac Help indexes. Oh, and fonts can be dramatically affected too— which can affect everything.

One thing I'm still trying to wrap my brain around is how Font Book (Panther) handles fonts. What I've seen is that it easily gets confused when you are adding fonts— immediately seeing some, but not showing others until it has been quit and reopened (or stranger, only after you have clicked around a bit in its lists). I've seen this behavior on a variety of Macs from my own PowerBook 17" to G4 and G5 workstations.

But clearing the cache files seems to be the magic bullet when dealing with font issues. So, in a nutshell, here's what you do. Caches can be found in three places:

YourHD/Library/Caches
YourHD/System/Library/Caches
YourHD/Users/yourhome/Library/Caches

In Panther, you can go to these three places, do a Select All (inside the Caches folder) and trash everything; Panther will prompt you for your administrator password to do this.

In Jaguar or earlier, you won't be able to trash everything in these folders— you will get a warning that you don't have enough privileges to do it. Just hit continue and let it trash what it can; typically the caches owned by the system aren't your problem (and if they are, you'll be best served by taking a trip to the terminal, which I won't cover here).

Make sure you don't have any apps open when you do this, as they might be using one or more of these files. When you are done, immediately log-out and back in (or restart). It will probably take a bit longer to reboot or login than normal, as some of the cache you trashed affect this. Once up, see if your problem is gone.

This cures a lot of ailments for me— particularly after long sessions of new installations and updates such as you would do with a new system.