How do I prevent OS X from automatically installing app files on my drive

Question

I have just reinstalled my Air with Lion. I didn't want to do a Time Machine restore, as I really didn't want any of the old apps, and I'd like to manually sort through my home folder and discard old crud.

After copying back my previous hard drive contents to ~/PREV, I noticed that Spotlight would suggest to launch apps that existed there, even though I hadn't "installed" them, like copied them to the /Applications folder or run their installers (for those that have them).

I quickly updated the Spotlight preferences to not index the ~/PREV folder (no need to, anyway, as it was only a temporary folder). That fixed that.

Now, I just discovered that Finder has context menu items stemming from BetterZip, which is now in my Downloads folder, having been copied over from my PREV folder. I did not install BetterZip.

What the ....? Somehow OS X is automagically installing .app files whereever it finds them? How on earth is this a good idea? What is OS X doing behind my back? And most importantly, how do I stop this crazy behavior?

Thanks :)

Answer 1

Okay, so so far I have no idea how to prevent .app bundles from being automatically "registered", but I now know how to repair the system.

It seems that it's lsregister which is responsible for scanning the system for .app bundles with launch services defined, and then automatically registering them in the launch services database. Seems insane, but apparently this is intended. Possibly to help with restoring from Time Machine backups.

AFAICT, no other configuration is being done, and no configuration files or other app-specific files are being copied from the bundles, so the damage is pretty mild and easily fixable. Also, it would appear that simply deleting the .app folders, zipping them up, or moving them way outside the reach of lsregister (like on a network drive or an external disk, perhaps, though I've read one guy complaining that even different partitions will be scanned) will eventually clear up those launch services. Though it should happen on logout/login, I wasn't able to get rid of them by doing this.

Zipping up my .app bundle and then issuing (in a terminal) —

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user

— cleaned up my launch services database without having to log out and back in (which didn't work in the first place) or restarting (haven't tried it).

I've noticed that placing .app bundles in a hidden folder, i.e. one with a dot as the first character, e.g. ".my-downloads", will stop Spotlight from indexing them and presenting them as launchable apps. I'm wondering if the same applies to the lsregister scanning. If so, putting my downloads in ~/.downloads and then simply creating a symlink to this folder as "Downloads" should keep me safe. Gonna try that out.

Answer 2

The Apps that the Finder shows in the context menu "Open with..." are not determined by Spotlight. Independently of Spotlight the System scans for all .app files on your disk and builds a database of Apps and the file types they can open. As long as you have an App on your disk, the Finder will offer to open files with it.

AFAIK, you can only prevent this behavior by either moving your apps to another disk, deleting them entirely or (what I often do) zipping them.

(By the way, OS X is not installing the Apps. Usually an App is 'installed' when it just is on your disk. Installing like on Windows is hardly ever necessary for an App to run on OS X)