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I want to set up automated backups that are kept safe from myself (in case a virus pwns me). The problem is the "create" and "delete" permissions are the same thing: write permission. So what can I do about it? Is it possible to decouple the create/delete permissions?

Another option could be to let the user "root" make the backups. The problem is my home directory is encrypted, and I don't want to backup everything.

Any ideas?

For the backups I'm using Deja Dup, which is installed by default in Fedora and Ubuntu.

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Have you heard of extended attributes on ext filesystems? man chattr maybe shows you some hints for a solution, i. e. there's the so called immuteable bit (+i) which denys the deletion of files. – noggerl Oct 17 '13 at 21:59
Backup to write-once media (cd-r,dvd-r). Take a strong look at write-once filesystems. – Zoredache Oct 17 '13 at 22:05
up vote 1 down vote accepted

Create another user account on your machine (or use root like you mention?). Then your backup does something like this:

  • Copies your files to a location where both of you have read/write access
  • The other users account has some kind of automated process (cron?) that then moves these files to a location where it has read/write access but you only have read access
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