Unable to use Su

[rayblasdel]

I just finished setting up my new installation. Installed all the programs I wanted. Finally was starting to try and configure some of the files. Only to run into the age old problems with permissions. I've killed Linux installations with the chmod. I once made the root unreadable. What fun that was.

But getting to my current problem. I was trying to modify a lot of files under the usr/ directory and I came up with the brilliant idea of adding myself to the 'root' group and chmod -R 775 usr/. At least I though it was brilliant, I finished making a few modifications, and needed to download a library. When I tried to load synaptic I got an ugly error.

Error - KDE su
Su returned with an error.

I'm not sure what to do now. I tried to use su from the command line and it says "Authentication failure". Any suggestions would be great thanks.

Mike

[Rog131]

Re: Unable to use Su

From sudo vs. su (http://www.tuxmagazine.com/node/1000148)

Both the Knoppix and Ubuntu/Kubuntu distributions don't include the su command nor do the have root logins. The only way to get administrator privileges at the command-line level is to use sudo. With Knoppix running from a live CD there are no user logins so sudo happens with no questions asked.

With Kubuntu, it works a bit different. When you enter the sudo command for the first time, you will be prompted for a password. What password? Yours. That is, the password you normally use to log in. This is to prevent someone walking over to an unattended system from getting root access. In order to make it more convenient to do a series of commands as root, Kubuntu remembers that you have run as root recently and doesn't require the password. But, after a short idle period, you will be asked for it again.

Use sudo and/or kdesu.
(To run the graphical configuration utilities use kdesu)

Editing Files that Belong to Root
http://www.psychocats.net/ubuntu/permissions

RootSudo
https://help.ubuntu.com/community/RootSudo

More:
Unofficial Ubuntu 6.06 (Dapper Drake) Linux Starter Guide
http://ubuntuguide.org/wiki/Dapper

-> How to set/change/enable root user password

[rayblasdel]

Re: Unable to use Su

^.^;; Not exactly what I was going for.

My problem isn't so much what to do under normal circumstances.

The whole authentication structure of KDE seems to be falling apart. Where it used to ask me for the root password to continue, errors are being displayed. Even sudo under the command prompt errors. Put simply I have to way to run any command under root.

[hungrybeast]

Re: Unable to use Su

Just in case you didn't know, the root account is disabled in Ubuntu. If you want to mess with privileges, just do a clean install, since yours is broken beyond repair and then go to menu>system settings>users&groups.

[Gezzer]

Re: Unable to use Su

try in a konsole

sudo passwd root
enter your password

then re-enter this pass word
and enter it again

this makes the root password the same as your password
and will enable su system wide ...

[kubicle]

Re: Unable to use Su

But getting to my current problem. I was trying to modify a lot of files under the usr/ directory and I came up with the brilliant idea of adding myself to the 'root' group and chmod -R 775 usr/. At least I though it was brilliant, I finished making a few modifications, and needed to download a library. When I tried to load synaptic I got an ugly error.

chmod/chowning system folders if you're not absolutely sure about what the effects will be is the fastest way to hose an installation. Even if you know what you doing, using the recursive '-R' option is very dangerous.

There are many files/directories in system folders that have different permissions and ownerships, and they won't work properly (or not at all) if the permissions/ownerships are changed. If you use the -R option it will change the ownerships/permissions uniformally, and it's very hard (if not impossible) to get back where you started since there is no undo option (changing back with -R option won't work since the files had different permissions/ownerships to begin with).

To the problem:
Is your user still part of the admin group (after you edited groups)?
Only admin's can use sudo/kdesu