[arch-general] No login after update

[brent s.]

On 8/19/20 15:02, Manuel Reimer wrote:
> Hello,
> 
> I know that Arch is not for the "average user" and some background
> knowledge is expected, but this was the first time I needed a boot stick
> since I think at least one year.
> 
> Some minutes ago I did a regular system update and after that decided to
> reboot. After reboot I was unable to log into my system. After fiddling
> a bit I rebooted to an Arch boot stick to find the following message in
> pacman.log:
> 
> [2020-08-19T20:42:55+0200] [ALPM] warning: /etc/pam.d/system-login
> installed as
> /etc/pam.d/system-login.pacnew
> 
> As this seemed to be a candidate that may cause login problems, I
> deleted "system-login" and moved the ".pacnew" into place.
> 
> After reboot I'm now able to log in again...
> 
> IMHO something like this should not happen...
> 
> Maybe it's worth a note on the Arch homepage that it is important to
> move this pacnew into place before reboot?
> 
> Manuel

I'm just going to reiterate some things, and offer a solution that would
have saved you this headache, and then I'm ignoring this thread as it's
tiresome.

1.) .pacnew files shouldn't be ignored. They are only created if *you*
(or a mispackaged software) have modified files provided by a package
from their default state.

2.) True of anything, really, but don't modify PAM files unless you have
a significant understanding to a complete grok of what you're doing.

3.) This isn't a news item, as it's isolated to your particular install
and customizations.

As for the solution,

https://aur.archlinux.org/packages/etc-update/

Ta-da. There are other packages that do similar things.

You could even have it run automatically after certain packages update
with a hook[0].

By running that after your -Sy and before the reboot, you'd see that the
line present in your configuration is not part of the default managed by
pacman/the package, with the option to:

- remove it (effectively reverting to the default file as provided by
the package)
- merge it with the new one
- interactively edit

etc. It even cleans up .pacnew files for you after you've made your
decisions. You now have no excuse to have .pacnew files all over nor to
have changes that are incompatible with new software (provided you read
the software's release notes to see if the deprecated, renamed, etc. a
configuration in the new version).


[0] https://jlk.fjfi.cvut.cz/arch/manpages/man/alpm-hooks.5

-- 
brent saner
https://square-r00t.net/
GPG info: https://square-r00t.net/gpg-info

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