Lost my root password in a VM

JeremyBoden · 12-16-2017, 03:29 PM

I have a Ubuntu VM and I destroyed the password on the admin user (I was foolishly renaming the user).

Do I just get a fresh DVD to reset the user password?
I'm loath to re-configure a completely fresh version of the VM.

frankbell · 12-16-2017, 07:34 PM

I think this thread from Ubuntu will be helpful: https://askubuntu.com/questions/2400...ative-password

!!! · 12-16-2017, 10:33 PM

Yes (dvd) but this gives me a chance to post a 'burning Story share' here:
Yesterday, my fav trick, grub e init=/bin/sh rw, failed (I think it just rebooted!!!)
Further inspection (as user; root inaccessible) found: sh -> dash; static-sh -> busybox!!!
On that circa-6/14 FrankenMint(?) init=/static-sh got me a uid 0 #, so I could 'attack' shadow.
Strange? Normal? p.s. hdd 'rescue' didn't (seem to) work &isn't primitive enuf for this mll user

AwesomeMachine · 12-16-2017, 11:12 PM

You boot the install DVD into rescue mode, open a root shell, and change the PW with passwd.

JeremyBoden · 12-17-2017, 08:10 AM

Normal methods don't work in a VM.

I suppose I could create a second VM, create appropriate users & copy appropriate bits of
/etc/passwd & /etc/shadow into the first VM (which I spent some time on configuration)?

allend · 12-17-2017, 09:02 AM

Have you tried mounting the VM image, so that you can edit it directly?
I recently used the procedure here for a raw image containing logical volumes and it worked for me. I have also used qemu-nbd with success in the past.

JeremyBoden · 12-17-2017, 10:21 AM

!!!!!Yuck!!!!! That

Code:

https://somepalli.wordpress.com/2015/10/01/how-to-mount-virtualbox-vdi-with-lvm-partition-on-ubuntu/

I wouldn't try that procedure - it sounds so very risky with regard to the non-VM components on my PC.

I've been trying to edit the VM and destroyed it; but it wasn't of value beyond a considerable time configuring it.
So the question is now moot for me.

Mill J · 12-18-2017, 05:56 PM

Doesn't it work to change the virtual optical drive for the VM to a live iso and booting?

JeremyBoden · 12-18-2017, 07:22 PM

Normally I would have been able to edit GRUB to get into single-user mode & fix it that way.

However, starting a VM hides all this and whilst I tried booting with a live DVD, this doesn't contain a relevant password entry.
Actually, I'm pretty certain that renaming a user in the /etc/passwd file was a stupid thing to do.

Anyway, the VM has now been replaced.
Thanks for your interest.

!!! · 12-19-2017, 03:04 AM

Oh, ooops, you're probably not using VirtualBox

qemu? kvm? (time to 'bump' these up, on my to-learn list

)

business_kid · 12-19-2017, 03:25 AM

There's a line about HIDDENMENU in /etc/default/grub, and if you comment that out, you can at least see what's going on.

_roman_ · 12-19-2017, 07:26 AM

Just setup the user again.
I assume you are aware of

Quote:

ASUS-G75VW /home/roman # man useradd
ASUS-G75VW /home/roman # man userdel

You should never use an editor on those files respectively

JeremyBoden · 12-19-2017, 07:32 AM

No - I am using VirtualBox - it seems to be rather inefficient, but easy to set up.
Must try to see if kvm runs on a spare ancient laptop to see what happens.

Quote:

qemu? kvm? (time to 'bump' these up, on my to-learn list

)

joe_2000 · 12-19-2017, 07:53 AM

You could boot a live image and chroot into the system to change the root and/or user password...

JeremyBoden · 12-19-2017, 08:43 AM

I don't usually use Ubuntu.
As a VirtualBox VM there's no way to drop into a CLI.

I'm coming to realise that I'd already messed up the VM (by editing /etc/passwd) and anyway Ubuntu isn't keen on letting you use root in the GUI.