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From: The Natural Philosopher <tnp@invalid.invalid>
Newsgroups: comp.os.linux.misc
Subject: Re: Not a request for help, but an explanation?
Date: Sat, 11 May 2024 08:58:09 +0100
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On 11/05/2024 05:55, Borax Man wrote:
> On Thu, 9 May 2024 12:59:57 +0100
> The Natural Philosopher <tnp@invalid.invalid> wrote:
> 
>> On 09/05/2024 11:40, Borax Man wrote:
>>> On 2024-05-08, The Natural Philosopher <tnp@invalid.invalid> wrote:
>>>> Yesterday, I installed the latest kernel in my mint MATE 20.3 desktop
>>>> here. It advised me to reboot, so I selected the reboot option after
>>>> closing all programs, and away we went. It rebooted fine and I got a
>>>> login prompt, that looked oddly different. I think it had my full name
>>>> instead of nothing above the login prompt.
>>>>
>>>> And no matter what I typed in as password, it wouldn't accept it.
>>>>
>>>> Thinking I might have to repair something from a live installation disk,
>>>> I decided that at least a hard reboot might be worth trying, and with a
>>>> proper power off it rebooted as normal.
>>>>
>>>> Anyone have a clue as to what that might have been?
>>>>
>>>> I am the only user on the system. It's mine, all mine, and one else ever
>>>> uses it.
>>>>
>>>>   
>>>
>>> We should first establish whether the problem is authentication, or
>>> something else.
>>>
>>> Are we talking about a graphical login prompt, or the console, text
>>> mode login prompt?  Do you get an error message?  What does it say?
>>> How does it fail?
>>>    
>> It was  a normal GUI login screen except that instead of a normal input
>> box, it had my full name over it, possibly as if I was not the default user.
>>
>> But I am the ONLY user!
>>
> 
> I think Mint uses Light DM, which is the one I use.  I see that
> behaviour myself, where it displays the username.  If you press up and
> down, you can choose between the users.  I'm not sure how that would
> act if there is only the one user, but maybe try the up and down
> cursor keys to see if it selects or unselects something.
> 
>>> Try switching to a text based virtual console, pressing CTRL-ALT-F2
>>> should do it.  Then try logging in with your username then password.
>>> If that logs in, then at least your credentials still work.  Type
>>> 'logout' then enter to logout of the text prompt and press CTRL-ALT-F7
>>> to go back to the graphical prompt.
>>>    
>> Cant reproduce it. As I said it only happened when I rebooted rather
>> than shut down the system
>>
>>> At the graphical prompt, is it asking specifically for your password,
>>> or for a username?  Is there a way to change the username, or type it
>>> in?
>>>    
>> As I said, it only prompted for the password.  And failed to accept it.
>>
>> This is a mint login screen:
>>
>> https://fostips.com/login-background-linux-mint-21/
>>
>> As you can see normally it has the default login name above the password
>> entry on the left.
>>
>> In the odd case it had my FULL name ABOVE the whole box on the RIGHT.
>> I am wondering if it had defaulted to an unknown user on soft restart
>>
>>
>>> Let us know how you go.
>>
>> As I said, hard reset restored normal behaviour. It was only a curiosity
>> as to why a soft restart might have been different....
>>
> 
> I'm guessing by what you mean by "can't reproduce it", is that the
> text based login worked.
> 

No. Powering the machine off, worked

That is the curiousity.

What information was retained across a soft reboot that was not retained 
in a power off situation

I have on many occasions had a machine hang after a soft reboot, and yet 
behave perfectly normally once powered down and restarted. Fine, the 
hardware would always be in a different state on soft restart, but this 
is more like some software values neing preserved across a restart.




> My initial thought was some temporary file, which saved state, but
> that should have been cleared on reboot, regardless of whether soft or
> hard.
> 
That's one I hadn't thought of. Mmm.

> LightDM keeps logs, these can be helpful.  They should be located at
> /var/log/lightdm
> 
> lightdm.log will list the results of authentication, and whether it
> was successfull or not.  During failure, check this log (log in at
> text console if necessary) and see what it says about the
> authentication failure.
> 
I might try that if I have time.

TBH I am only vaguely interested in what *might* have caused it, rather 
than pinning it down exactly. Life is too short



-- 
“The ultimate result of shielding men from the effects of folly is to 
fill the world with fools.”

Herbert Spencer