Recovering ubuntu 18.04 system password

Ubuntu
1

A mystery has caused the login passwords for my (two) users to fail to work. There is no error or notification of bad password match. The system just returns to the login screen after I enter the password I’ve used for many years. There are a couple of suggested processes on the internet: one involves using the recovery mode, the other edits the GRUB menu. I’ve tried both of these but no help.
Any ideas?

2

@castlesbob …
You might try this https://linuxconfig.org/recover-reset-forgotten-linux-root-password, I have used this before.
John the Ripper password cracker This one is not free, and I have never used it.
If you have a backup you might just restore.
You might just consider updating 18.04 with an updated install.

1 Like
3

It may not be a corrupted password but X failing to start. Which desktop are you using?
Have you done any updates recently? Which Graphics card?

4

The machine is an old ASUS e403. The graphics card is whatever ASUS put in. Sorry I don’t know which one. The desktop is just the standard 18.04 version. I have done no updates although the Ubuntu “Software Updater” runs automatically.

Here’s the weird thing: I can get to the root shell, can examine the hard disk, execute commands. The screen looks pretty much like an ordinary terminal screen but when I reboot, it goes to the login screen, accepts the passwords I give it and returns to the login screen.

5

What happens in the termial if you type lightdm or startx? what error messages do you get?

6

Here’s another bit of info. I changed the root password and my own and when in terminal mode, both are recognized. So kc1di may be right.
So, to kc1di: I tried “startx” and “lightdm” both from the root shell and my own and I get the same response in each case. The response is “command not found”.
Hmm…

7

are you connected to the internet from the terminal? If so try this command
sudo apt update && sudo apt upgrade
report any error messages you get.

8

Well, it looks like the problem isn’t the password. I got to the root terminal and changed password. The problem persists. I believe the problem is something I’ve seen referred to elsewhere: that is, a “login loop”. In other words the system keeps regenerating the login screen regardless of the password input. This has be baffled too.

9

@castlesbob
May be time to bite the bullet and replace Ubuntu 18.04.

10

The login screen is controlled by elogind . Have a look at its config file in /etc and see if you can fiddle some settings. I dont know which setting. I have seen this login loop behaviour, and also seen falling into suspend during a boot. It seems elogind is unstable in some hardware, especially laptops.

Regards
Neville

11

[quote=“nevj, post:10, topic:8363, full:true”]

The login screen is controlled by elogind . Have a look at its config file in /etc and see if you can fiddle some settings. I dont know which setting. I have seen this login loop behaviour, and also seen falling into suspend during a boot. It seems elogind is unstable in some hardware, especially laptops.

Regards
Neville
[/quote],
Thanks for the response, Neville, but I can find no traces of elogind. I’m running Ubuntu 18.04.
Bob

12

It must be called something else in Ubuntu. Commonly referred to as the login daemon, it may be logind or something else. Try
ps ax | grep login
it may come up
Or search in /etc for something to do with logins.
In my Debian it is /etc/elogind/logind.conf that I edited to fix my problem laptop

Sorry I have never used Ubuntu.
Can someone answer this?

Neville

PS You may be able to access it with systemd if you are prepared to wade thru that

13

@castlesbob
Try /etc/systemd/logind.conf

Neville

14

Found it. Thanks Neville.
Bob

15

Hi @castlesbob ,Here is my logind.conf file from my old laptop

  This file is part of elogind.
#
#  elogind is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.
#
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See logind.conf(5) for details.

[Login]
#KillUserProcesses=no
#KillOnlyUsers=
#KillExcludeUsers=root
#InhibitDelayMaxSec=5
HandlePowerKey=ignore
HandleSuspendKey=ignore
HandleHibernateKey=ignore
HandleLidSwitch=ignore
HandleLidSwitchExtern=ignore
HandleLidSwitchDocked=ignore
#PowerKeyIgnoreInhibited=no
#SuspendKeyIgnoreInhibited=no
#HibernateKeyIgnoreInhibited=no
#LidSwitchIgnoreInhibited=yes
#HoldoffTimeoutSec=30s
#IdleAction=ignore
#IdleActionSec=30min
#RuntimeDirectorySize=10%
#RuntimeDirectoryInodes=400k
#RemoveIPC=yes
#InhibitorsMax=8192
#SessionsMax=8192

[Sleep]
#AllowSuspend=yes
#AllowHibernation=yes
#AllowSuspendThenHibernate=yes
#AllowHybridSleep=yes
#AllowPowerOffInterrupts=no
#BroadcastPowerOffInterrupts=yes
#AllowSuspendInterrupts=no
#BroadcastSuspendInterrupts=yes
#HandleNvidiaSleep=no
#SuspendState=mem standby freeze
#SuspendMode=
#HibernateState=disk
#HibernateMode=platform shutdown
#HybridSleepState=disk
#HybridSleepMode=suspend platform shutdown
#HibernateDelaySec=1080
<\pre>
You can see I have removed the '#' from all those lines that start with 'Handle'
That may not fix your issue, but worth a try.
If you edit it, make a backup copy first ... one slip in the editor can ruin system fiies!
Cheers
Neville