> On 23. Jun 2020, at 21:25, Andrew C Aitchison <[log in to unmask]> wrote:
> 
> On Tue, 23 Jun 2020, Konstantin Olchanski wrote:
> 
>> On Tue, Jun 23, 2020 at 10:49:48AM +0200, Elio Fabri wrote:
>>> Hi all,
>>> I need help (at lest a link) as to how to recover my root password.
>>> I'm using SL6.2. The password I remember by heart is no longer
>>> accepted, neither for the su command nor for sudo.
>>> Thx
>> 
>> While you cannot "recover" the root password, if you have physical access
>> to the machine, you can bypass it, login as root and reset the password:
>> remove the boot disk from problem machine, attach it to a 2nd computer,
>> mount the root partition, go to root/.ssh and install your ssh key. unmount,
>> reassemble problem computer, boot, ssh into root, done. While the boot disk
>> is mounted on the 2nd computer, in addition to installing the ssh key,
>> you can also reset the password (edit /etc/shadow) or setup "sudo" for
>> password-less "sudo root" (recent Ubuntu are setup this way, you never actually
>> use the root password to login into root).
> 
> If you remember the BIOS password, or never set one,
> you can boot from an install or rescue disk/memory stick,
> and do that "second computer" stuff without moving the
> disk to another machine.

It seems surprisingly little known that there's a *much* simpler and faster way.

1) In the boot loader, hit 'e' and add "init=/bin/sh" to the kernel commandline. If you set a boot loader password (and these instructions should make clear why you should), you'll obviously have to remember that. After boot, you'll get a root prompt but a r/o mounted /
2) remount -oremount,rw /
3) set the root passowrd with the passwd command
4) sync; remount -oremount,ro /
5) hit ctrl-alt-del to reboot

And if you don't have the SL_password_for_singleuser installed, which isn't the default I think, it's even easier: just add "1" to the kernel command line.

HTH,
- Stephan