How to gain single user access due to a lost root password

[mauricio]

Hello

I've an SD card with Debian image on it (Bullseye).

I was developing on an A20, during last year.

I've forgotten the root password (also my common user password), so I can't do login.

I've tryed to login (through serial screen) in single user mode, after modifiying /boot/uEnv.txt, adding :

Code Select Expand

optargs=single
But login prompt is still asking me for a password:

Code Select Expand

Give root password for maintenance
(or press Control-D to continue):
If I press Control-D, I receive:

Code Select Expand

Reloading system manager configuration
Starting default target
And login prompt

Please, there is something I can do to gain access so I can reset password ?

Thanks

[LubOlimex]

Aside from what Google says about "reset forgotten root and user password" -maybe try to access the board via SHH over the Ethernet, the username and password should still be the original ones user olimex and password olimex

[mauricio]

Thank you LubOlimex

I did change root and olimex password at the begining, last year, both forgoten

I did search for "reset forgotten root and user password", but since there's no GRUB but U-Boot

I stopped autoboot hitting any key at begining. But here on I don't know how to proceed to add "single" to boot options

Also found you can pass boot parameters using uEnv.txt file

# optargs - Optional arguments passed to the kernel

so I add

Code Select Expand

optargs=single
This last one seems to be wrong

Any help on how to pass "single" to boot options, so no login requiered ?

Or any other method. Some where in time (probably other linux image) I remenber twiking some option some where to enable/disable login requirement when connected through
serial cable, maybe?

Thanks

[JohnS]

Mount the SD card on another computer (laptop etc) and change the vital files involved in what you want e.g. edit /etc/passwd (& others) to make a root with no password.

John

[mauricio]

Thank you JohnS

I've done as you said. Following this post https://unix.stackexchange.com/questions/76313/change-password-of-a-user-in-etc-shadow I was able to login as root and reset all my passwords

Thanks !