I have the root account enabled. I have degraded the user (say kenneth) to a standard account and I have set the Defaults rootpw flag in sudoers.

When I use sudo it correctly prompt for root password, but then it returns

kenneth is not in the sudoers file. This incident will be reported.

I'm asking this question here (AskUbuntu) because I have 3 other Linux systems and the same problem doesn't occur there. Is there any difference(any significant change that apply only on Ubuntu) that I have to know or I'm missing something else ?

sudoers file

# This file MUST be edited with the 'visudo' command as root.
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
# See the man page for details on how to write a sudoers file.
Defaults    rootpw
Defaults    env_reset
Defaults    mail_badpass
Defaults    secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root    ALL=(ALL:ALL) ALL

# Members of the admin group may gain root privileges
#%admin ALL=(ALL) ALL

# Allow members of group sudo to execute any command
%sudo   ALL=(ALL:ALL) ALL

# See sudoers(5) for more information on "#include" directives:

#includedir /etc/sudoers.d

groups kenneth

kenneth : kenneth cdrom dip adm plugdev lpadmin sambashare vboxusers

groups root

root : root sudo
  • Funny thing now is, even when I upgrade kenneth to administrator (add him to sudo group) the same problem persist. I cannot use sudo with kenneth's password (tried of course with Defaults rootpw commented out)
    – NickTux
    Mar 21, 2014 at 10:50

1 Answer 1


My understanding was that rootpw just changes the behaviour of the password prompt. Your users still need to be named (explicitly, or through groups) /etc/sudoers.

In this case kenneth isn't. Fix that and this should work.

On a side note, this seems like a really backwards use of sudo. This is exactly the sort of behaviour sudo was invented to prevent against. You might as well just su.

  • Something wrecked here Oli, but I don't know what. As I have commented at my own question, even when I restore the user (as an admin - by adding him to sudo group) sudo refuses to run properly. I have now added a new user (say john) just to test, and there everything works. (Defaults rootpw and the like).
    – NickTux
    Mar 21, 2014 at 11:29
  • 1
    In the case where you're adding the user to the right group, are you logging out and in again? That's required for a user to pick up group changes.
    – Oli
    Mar 21, 2014 at 11:36
  • I have added and removed 3 comments at the last 10-15 minutes. But I think this is the final. Here is the deal. If the user kenneth don't belong to sudo group, the sudo command doesn't work properly with the rootpw flag on. Additionally you have to logout (completely - login shell also) in order for changes to take effect. That's it.
    – NickTux
    Mar 21, 2014 at 12:26
  • @Oli newgrp(1) should also work though.
    – Pryftan
    Feb 21, 2018 at 19:46

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .