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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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ELI5: What is an immutable OS, in practical terms? (feddit.de)

submitted 2 years ago* (last edited 2 years ago) by [email protected] to c/[email protected]

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I've heard of immutable OS's like Fedora Silverblue. As far as I understand it, this means that "system files" are read-only, and that this is more secure.

What I struggle to understand is, what does that mean in practical terms? How does installing packages or configuring software work, if system files can't be changed?

Another thing I don't really understand is what the benefits as an end user? What kinds of things can I do (or can be done by malware or someone else) to my Arch system that couldn't be done on an immutable system? I get that there's a security benefit just in that malware can't change system files -- but that is achieved by proper permission management on traditional systems too.

And I understand the benefit of something declarative like NixOS or Guix, which are also immutable. But a lot of OS's seem to be immutable but not purely declarative. I'm struggling to understand why that's useful.

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[–] [email protected] 3 points 2 years ago (1 children)

The most basic benefit of immutable OSes like Fedora Silverblue is that you are prevented from messing up your system enough that you are unable to boot into it and fix it. This isn't strictly true, you can always go out of your way to screw things up (say deleting required partitions), but in normal usage you will always have a backup to boot and fix whatever you messed up. It also makes it extremely easy to undo things even if they aren't errors.

It's possible to do this without immutable OSes using btrfs snapshots before you change anything system-wide, in fact I believe MicroOS uses btrfs snapshots for their immutable system, but that adds cognitive load as it requires you to remember to create a snapshot. OpenSUSE Tumbleweed provides snapshotting automatically and adds entries to the bootloader for previous iterations, but it isn't immutable because you can still go and modify your root partition without taking a snapshot. MicroOS, however, has a read-only root partition so it becomes a lot more difficult to make a change without a snapshot. You can still do it, but you have to go out of your way to do it.

[–] [email protected] 1 points 2 years ago

Adding to this, Snapper (snapshotting utility for btrfs) has a way to enable snapshots after each install of an app, and I'm pretty sure there's a package somewhere that adds btrfs snapshots to grub entries, so you could theoretically boot back into a stable version of your system pretty easily