You may remove read "r" attributes to avoid reading your file so that...

You may remove read "r" attributes to avoid reading your file so that particular user cannot read it, you've U-G-O (User - Group - Other) attributes on major Linux filesystems, or you can use ACL for fine tuning on certain file systems.
Is this what you'd like to do or you need to do something else, let me know what you want to do with a practical example and we may discuss available solutions (if any..)

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