Ubuntu Linux Restore admin / root level permissions

by on November 1, 2007 · 2 comments· LAST UPDATED November 1, 2007

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I was writing and testing few python scripts (yes I'm moving lot of stuff from shell / perl to python these days) and accidentally I renamed my own user account from vivek to test. However, I did not noticed change until I rebooted my box. Now I cannot run sudo (or become a root user) and cannot access special devices such as sound or video.

By default your first account has all power via sudo under Ubuntu Linux. There is a special group called adm and admin which grants unlimited power via sudo.

The only solution was to boot computer in emergency mode (reboot computer and at grub menu select recovery mode kernel), open /etc/group file and add user vivek to admin and adm group:
# vi /etc/group
Add user vivek to admin and adm group:
admin:x:117:vivek
adm:x:4:vivek

Save and close the file.

Now I'm able to run sudo and do other stuff. Luckily, my scripts always backup critical files before modification. So I was able to restore permission instantly. Here is my group membership with all power and glory ;)
$ id
$ groups

Output:

vivek adm dialout cdrom floppy audio dip video plugdev scanner netdev lpadmin powerdev admin
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{ 2 comments… read them below or add one }

1 mikey June 27, 2011 at 12:45 am

Thank god you pasted this article – I had previously followed your usermod article and it destroyed all my permissions. Thanks! Needed to use the -a option.

So uh, please update that article so that other people do not destroy their permissions too ;)

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2 Layolayo April 20, 2012 at 1:39 pm

Nice one! Similar scenario for me last night – panicked then remembered there was a work around. I used :
useradd USERNAME admin
useradd USERNAME adm

with same result – also used /var/backup/group.bak for previous group membership

Now I have created another Administrator account (called Saviour) just in case I mess up again – I should really stop fiddling about!

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