How does snapper work - does it revert to pre or post?

Had cause to use snapper just now to take the laptop back in time to a previius upgrade.

Haven’t upgraded in a good while, so was still on 5.9.11 from november 2020.

Selected the following:
191 & 192 / Pre & Post / 2020-11-29
Clicked modify, accepted, ticked all three chunks of system to modify and started the processs.

Snapper spooled away for a good long while, with the log making repeated references to kernel 5.7.11.
Fair enough i thought, it’s a long way back to the pre novemeber state, but once i get there i can always update again.

Process finished, so i restart and when back in check sysinfo… Only to find to my surprise that it still shows the system as 5.9.11!

What exactly did i do?
By using pretty much default options did i somehow revert to the ‘Post’ state?
i.e. Back to how the system was in Novemeber 2020 - after the upgrade.

And if that is the case, why did snapper spend all that time spooling information about 5.7.11 past my eyeballs.

It feels like i’m not really understanding what snapper is doing…


It looks like you used Yast to restore items from a snapshot, rather than roll back to a snapshot.

To roll back:
1 - From the boot menu select read only snapshots option, select the one you want to roll back to, and boot from it.
2 - After you have booted, if everything looks good, open a terminal and type “sudo snapper rollback” and reboot. If things don’t look ok, reboot and try another snapshot.

Note: even though the term used is “rollback”, after you have rolled back you can also select a “later” (timewise) snapshot than the one you rolled back to.

i did all this from within the snapper application, using the “modify” function…

snapper is a CLI application. I don’t think there is any GUI for snapper rollbacks. So, I assume you mean the YaST module for snapper?
“modify” doesn’t modify your system, it just modifies the snapshot. I don’t exactly know what the function does, it seams to do some cleaning up.
However, it’s just as doscott said. You have to type it as root in a terminal.
You can use

snapper list

to list the available snapshots. Since you have already opted for 191 & 192: 191 is the one “before” and 192 is the one “after” the event that triggered the snapshots.
So, you can directly go for a

snapper rollback 191

And of course:

man snapper