The "allow keychain access" feature is great, but creates a problem with multi-user computers. Is there a way to require a re-login without the keychain if the user name equals something that I can add to the opening script?
why not just disallow the keychain from being used for your file?
Anything you add as part of the opening script will run with a user already logged in, which is known as 'ersatz security' and more often than not, that is not secure at all. I would stay away from doing that.
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