Excluding Virus Definitions from Time Machine

Is it possible to exclude the malware definitions that are updated daily from Time Machine?
I ask this because it doesn’t seem to make much sense to back them up, and since they are updated more than once a day, TM ends up backing up at least 100 MB in malware definitions after each update.
And if I ever need to do a full restore from Time Machine, I don’t mind downloading all definitions necessary afterwards, as long as it works automatically.
My first suggestion is that I would like Avast! to have an option/preference to exclude definitions from backups.
But since that won’t probably be implemented, my second thought would be to exclude them from TM if Avast! can graciously recreate them on its own.

Thru some investigation they are apparently stored in: /Library/Application Support/Avast/files/defs

The /Library/Application Support/Avast folder is a protected folder, so I can’t really see what’s inside easily except via root or as super user in the Terminal.

If Avast! can recreate the definitions (by downloading new ones) automatically, what folders can I safely exclude (without breaking anything) from backing up thru TM?

Thank you.

Hallo, not only defs, but also Setup.filedir will contain daily updated stuff (megabytes of resulting size, after applying diffs).
But, because avast itself does some backups, and can re-create the whole appsupport dir from scratch, it’s quite possible to exclude the whole avast’s application support directory from TM. to minimise any overhead.

Regards,
pc

I can simply exclude the whole /Library/Application Support/Avast/ folder? (I got the impression my registration information was also kept there?). That’s even better, thanks.

Well, it is, but this is only one directory (“config”), which you could backup manually. Or, exclude from TM the “files” subfolder only, to get rid of daily updates overhead.

regards,
pc

If anyone else is interested in doing this, excluding only the definitions part (…/files), it’s not exactly straightforward, there are some peculiar steps that have to be made since this Avast folder is protected.

There are many ways to achieve this, this is the one I used:

  1. Via Time Machine preferences exclude /Library/Application Support/Avast (when you reach here you’ll see you can’t see what’s inside this folder).

  2. Launch an app that can edit plists with super user privileges, I use Property List Editor.app (comes with XCode), the free TextWrangler app can do it to.

In the Terminal/Command Line type:
sudo “/Developer/Applications/Utilities/Property List Editor.app/Contents/MacOS/Property List Editor” &
(you have to use the path to the executable inside the .app package, it’s always in the MacOS folder)
Type password when asked.
Open the file /Library/Preferences/com.apple.TimeMachine.plist
Go to the section ‘SkipPaths’
You’ll see your Avast exclusion there, now just add /files to the path.
Save and quit the app.

Another way would be to temporarily change the permissions of the Avast folder so you can add /files to the exclusion list without editing the file direclty.