su and rejected session manager rejection.

AngryLlama · 02-01-2007, 02:34 AM

Hello -

I recently performed a massive update on my Gentoo system. I do not believe that this problem is Gentoo-specific, so I am posting in this forum. All the software and components of my system seem to be running fine. However, I am having a problem with X applications when su'ing in as root (perhaps other users too).

Code:

llama@llamatron ~ $ xclock
llama@llamatron ~ $ su
Password: 
llamatron llama # xclock
Warning: Tried to connect to session manager, Authentication Rejected, reason : None of the authentication protocols specified are supported and host-based authentication failed

xlock runs in both cases. However, I get that warning when under su. The problem is solved when I use su - root:

Code:

llama@llamatron ~ $ su - root
Password: 
llamatron ~ # xclock

Strange... I've never used the hyphen before with su, but it works. I would like to return to my normal method of su if possible.

Thanks

nx5000 · 02-01-2007, 02:39 AM

su - will invoke a login shell
if root uses bash for example, look at the difference between bash login shells and non-login shells.
Better read YOUR man page of bash because behaviour are different among versions.

Quote:

When bash is invoked as an interactive login shell, or as a non-interactive shell
with the --login option, it first reads and executes commands from the file
/etc/profile, if that file exists. After reading that file, it looks for
~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and exe*
cutes commands from the first one that exists and is readable. The --noprofile
option may be used when the shell is started to inhibit this behavior.

When a login shell exits, bash reads and executes commands from the file
~/.bash_logout, if it exists.

When an interactive shell that is not a login shell is started, bash reads and exe*
cutes commands from ~/.bashrc, if that file exists. This may be inhibited by using
the --norc option. The --rcfile file option will force bash to read and execute
commands from file instead of ~/.bashrc.

So login shells will execute /etc/profile then the first in ~/.bash_profile, ~/.bash_login, ~/.profile. That's it.
For non login shells (su without -), it only executes ~/.bashrc

So check these files.
Never seen this warning.

AngryLlama · 02-01-2007, 02:56 AM

Quote:

Originally Posted by nx5000

su - will invoke a login shell
if root uses bash for example, look at the difference between bash login shells and non-login shells.
Better read YOUR man page of bash because behaviour are different among versions.

So login shells will execute /etc/profile then the first in ~/.bash_profile, ~/.bash_login, ~/.profile. That's it.
For non login shells (su without -), it only executes ~/.bashrc

So check these files.
Never seen this warning.

I'll get to the man pages tomorrow. My user and root's ~/.bash_profile just calls ~/.bashrc. The user and root's .bashrc only have some simple aliases and xterm title cases.

Now - I created a new user when I did my massive upgrade because I didn't want obsolete 2+ year old dot-files polluting my home directory. Investigating my original .bashrc reveals:

Code:

alias su="su -"

Perhaps I have always been prone to this warning. Oh well, it isn't fatal and I can just use this alias to fit my habit of only typing 'su'.

BTW, I just re-read my thread title.. Sort of redundant, huh?

nx5000 · 02-01-2007, 03:54 AM

Quote:

Originally Posted by AngryLlama

BTW, I just re-read my thread title.. Sort of redundant, huh?

Didn't see it the first time

alias su="su -" hummmmm this is not so clever

su - leads to
su - -
?
I wonder whats the result..

yes bash profile calls bashrc, its a shortcut that bash takes.
But if the user has a different shell then probably .profile is called only.

AngryLlama · 02-01-2007, 06:52 PM

Quote:

Originally Posted by nx5000

Didn't see it the first time

alias su="su -" hummmmm this is not so clever

su - leads to
su - -
?
I wonder whats the result..

yes bash profile calls bashrc, its a shortcut that bash takes.
But if the user has a different shell then probably .profile is called only.

Sigh.. I will just switch to using 'su -', although it would be nice to know what the underlying issue is.