where are my temporary internet files located for mac os x lion

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If you are using Safari, the cache is stored on ~/Library/Caches/com.apple.Safari, so you can go here to see the Internet temporary files. To access to that folder, open Finder, select Go menu > Go to Folder and type ~/Library/Caches/com.apple.Safari

If you want to open Cache.db, you can't, because there aren't any applications that can open that extension. However, that cache contains all the webpages information you have on Safari, so you don't need to open it in order to see what's there.

If you want to delete the cache, open Safari > Preferences > Advanced, and tick "Show Develop menu in menu bar". Then, close that window and go to Develop > Empty caches