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I have installed ubuntu and now I want to install flex. It asks for password but when I type my password, it asks me the password for root.

When I enter the password which I had specified during installation, it says, "Your authentication attempt was unsuccessful. Please try again."

Whether the password for root is locked or is it something else? The passwords I entered were correct.

I have also tried sudo su but it says, "Unable to change to sudoers gid :operation not permitted."

I have tried su also but when I enter the password it says, "Authentication failure".

Please help me out. I thought that maybe this is because the root user is locked by default. If so, how to recover from it? And if something else is the issue then what to do?

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  • In a terminal, sudo su is not working either?
    – grimpitch
    May 10, 2013 at 2:26
  • What command are you trying to run? Did you try running the command with sudo instead of becoming root with su then running the command?
    – notkevin
    May 10, 2013 at 2:34
  • sudo was also giving problem. i have re installed with diff. wubi.i thought problem was with wubi of 13.04 .now every thing works fine. thanks.i got solution on askubuntu.com/questions/283950/mountcant-read-proc-mounts
    – usmangani
    May 10, 2013 at 14:57
  • For voters: see OP's comment on 1st answer.
    – guntbert
    Nov 29, 2013 at 20:48

3 Answers 3

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The command you're looking for is sudo -s. You can also accomplish the same thing with sudo bash

su and sudo su doesn't work on Ubuntu for security reasons. It fails because the root user does not have a password, and those operations are you attempting to "log in" as user root

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  • 2
    sudo su sure does work, it's just a bit silly to run sudo to run su, when you can just run sudo -s if you want a shell as root.
    – psusi
    May 10, 2013 at 3:48
  • 1
    I found the answer. the problem was with wubi.i have re installed with wubi12.04. and working fine.
    – usmangani
    May 10, 2013 at 14:54
  • @usmangani just a tip, don't use wubi. It is not supported any more and causes more problems than it solves. Just install Ubuntu the regular way for the best experience (and more speed).
    – mniess
    Nov 29, 2013 at 15:49
2

Press Ctrl+Alt+F1, then log in and run the following command:

sudo chown -R user:user /home/user/.*

Where user is your user name, for example qasim:qasim.

Find further help here:

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0

You can add a "#" before

/usr/bin/sudo Ux, 

in

/etc/apparmor.d/abstractions/launchpad-integration

and i also removed the "#" from

#include <tunables/global>
#include <abstractions/lightdm>
#include <abstractions/lightdm_chromium-browser>

in /etc/apparmor.d/lightdm-guest-session

but i don't know if all of this is necessary

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