Nixpkgs: List-generations empty.

[MrSorcus]

Issue description

With efi & grub2.
Server (In grub menu 3 entries available):

root@server> nix-env --list-generations
root@server>

Laptop (Only 2 entries found, but in efi menu more than 100 entries exists.
nix-store --gc, nix-collect-garbage -d doesn't clean them...):

root@nixos_laptop> nix-env --list-generations
   1   2017-11-05 19:22:24   
   2   2017-11-06 09:07:46   (current)
root@nixos_laptop> ls /boot/loader/entries/
nixos-generation-216.conf  nixos-generation-218.conf  nixos-generation-220.conf  nixos-generation-222.conf
nixos-generation-217.conf  nixos-generation-219.conf  nixos-generation-221.conf  nixos-generation-223.conf

After nix-collect-garbage -d and nix-store --gc (after reboot to new generation) old entries still exist in grub/uefi menu. Why?

Steps to reproduce

Server configuration.nix - https://gist.github.com/MrSorcus/a52ecc23ee126bc847599241f560641b
Laptop configuration.nix - https://gist.github.com/MrSorcus/3aa2f023d580d9a4a54416e917b0e821
nix-install

Technical details

• System: (NixOS: nixos-version, Ubuntu/Fedora: lsb_release -a, ...)
  Laptop: 18.03pre119245.5cfd049a03 (Impala)
  Server: 18.03.git.eece875 (Impala)
• Nix version: (run nix-env --version)
  Laptop & Server: nix-env (Nix) 1.11.15
• Nixpkgs version: (run nix-instantiate --eval '<nixpkgs>' -A lib.nixpkgsVersion)
  Laptop: 18.03pre119245.5cfd049a03
  Server: 18.03.git.eece875
• Sandboxing enabled: (run grep build-use-sandbox /etc/nix/nix.conf)
  Laptop: build-use-sandbox = false
  Server: build-use-sandbox = true

[srhb]

Did you mean to list system generations?

nix-env --list-generations --profile /nix/var/nix/profiles/system

[MrSorcus]

Maybe. If --profile required, why in the manual nothing written about that?
Or i can't find it is...
Without --profile list/rollback/remove generations doesn't work...
But in manual all commands are written without this argument...

[srhb]

People do not tend to manipulate their system profiles with nix-env directly often, I think. Which part of the manual are you referring to?

[MrSorcus]

https://nixos.org/nix/manual/#sec-profiles
https://nixos.org/nix/manual/#operation-list-generations
https://nixos.org/nix/manual/#operation-delete-generations
https://nixos.org/nix/manual/#operation-switch-generation
https://nixos.org/nix/manual/#operation-rollback

[srhb]

The Nix manual doesn't deal with anything related to the system profile, since that's a NixOS-specific thing. Instead, check out the NixOS manual and see if that helps.

[MrSorcus]

Ok. Sorry, but how to delete old generations from uefi|grub?
nix-collect-garbage -d? Or nix-store --gc?
With grub2 after using both commands, entries not deleted from grub menu.

[srhb]

nix-collect-garbage -d or --delete-older-than ... as root is right. :)

[MrSorcus]

Ok, good. Why old entries still exist in grub/uefi menu? Bug or not?

[srhb]

Have you rebooted into your newest generation before garbage collecting? Otherwise I think the current system will be prevented from being gc'ed.

[MrSorcus]

Yes.

[srhb]

Hmm, not sure what's going on then. Perhaps someone else can weigh in.

[srhb]

@MrSorcus Perhaps you want to alter the issue text to refer to the problem at hand. The current one is a bit misleading. :)

[MrSorcus]

@srhb Now good?

[yegortimoshenko]

Are you sure you're running it as root? As in, sudo nix-collect-garbage -d.

[MrSorcus]

root@nixos_laptop> whoami
root

[MrSorcus]

Update.
Looks like that now it's working. But i'm not sure... I will try it later with clean installation.

[MrSorcus]

On a clean installation, everything is just as empty.
nix-env --list-generations does not show records.
Either the hands are curves, or Nix.

[trusktr]

This is a NixOS UX problem.

As a new user to NixOS, Googleing around for "nixos list generations" in order to see what generation I'm currently on leads to results like nix-env --list-generations which, as mentioned above, doesn't show system generations.

I'm a single user on my system, and using nix-env to manage packages doesn't seem like a good fit. I just want my system to have whatever I need, and prevent it from writing anything in my home folder.

I think the expectation that new NixOS users have is that nix-env --list-generations will simply list the system generations, not multi-user generations for the current user.

Maybe the command can be updated to show both, or someting, by default? As an example, the following would actually help new users get an idea of what's going on:

$ nix-env --list-generations
system:
   1   2020-01-06 19:08:56   
   2   2020-01-13 15:46:54   
   3   2020-01-13 16:34:14   
   4   2020-01-13 16:48:07   
   5   2020-01-13 21:19:21   
   6   2020-01-14 01:18:33   (current)

user:
   1   2020-01-07 18:32:25   
   2   2020-01-13 16:42:23   (current)

When people start using NixOS, they'll start with a configuration.nix file, and as a result it is intuitive to expect that nix-env --list-generations shows the system generations because those are what we start with.

I don't think it is likely that people using nix will start without NixOS (thus not care about the system generations), but I could be wrong.

All in all, as _awesome_ as the Nix system is, the CLIs are confusing to use from a UX perspective, especially for new people.

[nh2]

I agree, there should be something that makes it more obvious for users to discover that nix-env --list-generations --profile /nix/var/nix/profiles/system is the right thing to use for NixOS generations.

Perhaps we should have nixos-env that sets the --profile by default?

[ShamrockLee]

It would be helpful if there is a parameter like --list-system-generations.