root password from su account

Hy does anyone know how to recover the root password if i change to m su account and try to log back in as root i get authentification failure. I dont recall setting up a root password but i have to power down my bone each time im loggged in a su. which defeats the purpose being there.

On Sun, 27 Nov 2016 07:25:48 -0800 (PST), Ivor Meade
<ivormeade@gmail.com> declaimed the
following:

Hy does anyone know how to recover the root password if i change to m su
account and try to log back in as root i get authentification failure. I
dont recall setting up a root password but i have to power down my bone
each time im loggged in a su. which defeats the purpose being there.

  In my experience, standard images do not have a password on root.

  However, I don't understand your operating practices. For example, what
do you mean by an "su account"? The normal (pre-configured) user account is
"debian" with a password of "temppwd" (which it blasts to you on the screen
once you give it a valid username).

  The common/recommended practice is to use the "debian" (or other /user/
privilege) account to do most work, and use the "sudo" command when needing
to access root privileges (the "debian" account is preset so that sudo
doesn't even prompt you for its password -- unlike the Raspberry PI where
no default accounts can use sudo, one has to open a privileged console in
the GUI <G>).

  Getting to root (though still in the debian home directory) is simply:

login as: debian
Debian GNU/Linux 7

BeagleBoard.org Debian Image 2016-06-15

Support/FAQ: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian

default username:password is [debian:temppwd]

debian@192.168.2.105's password:
Last login: Fri Nov 25 17:57:44 2016 from 192.168.2.109
debian@beaglebone:~$ sudo su root
root@beaglebone:/home/debian# ls
bin HINT_BBB_SDcard.tar.gz home.tar.gz serial_hint.tar.gz
Desktop HINTn pthread threads.tar.gz
hint HINT_swap.tar.gz pthreads_hint.tar.gz

and returning to the user account is merely

root@beaglebone:/home/debian# exit
exit
debian@beaglebone:~$ ls
Desktop HINTn home.tar.gz serial_hint.tar.gz
HINT_BBB_SDcard.tar.gz bin pthread threads.tar.gz
HINT_swap.tar.gz hint pthreads_hint.tar.gz

  Granted, for one or two commands, one would not do the full "sudo su",
but just enter "sudo command".

  It almost sounds like you are logging in as "root", then use "su" to
change to a non-privileged account, and later are trying to use "su" to get
back to root. Since there is no password for root, su's request for a
password will subsequently fail.

debian@beaglebone:~$ su root
Password:
su: Authentication failure
debian@beaglebone:~$ sudo su -
root@beaglebone:~# ls
root@beaglebone:~# exit
logout
debian@beaglebone:~$ sudo su
root@beaglebone:/home/debian# exit
exit
debian@beaglebone:~$

  Ah... "su -" (still under sudo) puts one into the root directory (and
apparently a different PATH as "exit" echoes a different line).