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I wanted to change my username, and tried out this explanation here: https://askubuntu.com/a/205470/112035.

First, I changed the username in /etc/passwd to the new one. Then I wanted to change it at /etc/group too, but since changing it at the first file I can't login as root anymore.

Is there a way to solve this? Thanks in advance!

Community
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Dominik Berger
  • 148

4 Answers4

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You will need to get root privileges at boot time. Then you can revert the change you made and reset the password on the primary account.

How do I reset a lost administrative password?

Be very careful changing usernames. /etc/passwd associates each username with a user ID (number). In some places in the system the number is used, in others the name. To change a username without breaking things you therefore have to change the name everywhere it occurs. I would recommend that you not try to change your username unless you are an expert. If you are an expert then I don't have to tell you about usermod(8). ;-)

Community
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jdthood
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I'we lost my root acsess, but can login in ubuntu...

Solved with this metod:

Reboot in to recovery mode and to get Read/Write enabled done this

mount -o rw,remount /
chmod 0440 /etc/sudoers
chown root /etc/sudoers

Than added me to root user with this

sudo adduser <my username> sudo

When you replace my username with yours (without the <>)

To check username do this

ls /home

To change your password do this 

passwd <your password>

When you replace my password with yours (without the <>)

When done youst typereboot and you are done...

p.s. sorry for my bad English?!

user195385
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Reboot the computer into recovery mode (esc to grub and enter root prompt) and do

chmod 0440 /etc/sudoers
chown root /etc/sudoers

Reboot back to desktop and run in terminal:

sudo dpkg-reconfigure -a

This will bring you through a series of menus to allow you to reconfigure all your packages and should fix any permissions issues.

Cloudmeteor
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0

Could someone verify this?

In UNIX systems you also have an important file called /etc/shadow. Inside that file, you have encrypted password for each user. I think that you changed the files /etc/group and /etc/passwd but forgot to change the /etc/shadow. So now, you have changed a username, but you don't have actually a password for it. I am just theorizing here.

For example I created a dummy account, with dummy password. My contents of files are:

/etc/shadow
dummy:$6$ddvrCSTQ$4cAt8U.3sd6TQZ8Xi4VzOQv/GR7LA/bi72di9RE5v77y2U7os60DKbb0VLS.JPslf3g9GBBBzbNqW0y5ynkc11:15687:0:99999:7:::

/etc/group
dummy:x:1001:

/etc/passwd
dummy:x:1001:1001::/home/dummy:/bin/sh

Now I will remove the entry from /etc/shadow file. This is what I get:

su dummy
Password: <I type dummy here>
su: Authentication failure

So there you have it. You should generate a proper hash for your new user and it to /etc/shadow. Hope that helps.

Melon
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