problem regarding setting DISPLAY env variable and hostname

Giorgos Keramidas keramida at
Thu Feb 23 09:09:42 PST 2006

On 2006-02-23 08:38, Rob <rob at> wrote:
> > On 2006-02-22 13:07, Rob <rob at> wrote:
> > > So now Xorg does not give errors on startup or shutdown like the
> > >
> > > > > bad display name "xenon:0" in "remove" command    or
> > > > > bad display name "xenon:0  in "list" command
> > >
> > > But when not setting the DISPLAY variable explicitely anywhere I still
> > > get the error: "out of display lists" upon starting the program I want
> > > from xterm
> > >
> > > But then setting DISPLAY=xenon:0.0 export DISPLAY and then executing
> > > the program then gives the error:
> > >
> > > "Can't open display: xenon:0.0"   so I guess I am back to square one.
> > >
> > > Maybe I should call it a day and rest, haha.
> >
> > Just a wild guess, since I don't see why you should have problems
> > running programs like:
> >
> >     Can't open display: xenon:0.0
> >
> > Are you running X11 as a plain user and having problems to run programs
> > *after* using su(1) to become root or does this happen for all users in
> > all terminals?
> Hi Giorgos,
> I am trying to run a program from xterm as a normal user.  However,
> when su'ing in xterm, I am unable to run any programs.  Then I get the
> error:
> "Xlib: connection to ":0.0" refused by server
> Xlib: No protocol specified
> Error: Can't open display: :0.0

That's ok.  When you use su(1) to become root, you no longer have
permission to open programs on the display of the X server opened
by the plain user.

> setting for csh as root:  setenv DISPLAY xenon:0.0 then gives the error message:
> _XTransSocketINETConnect() can't get address for xenon:6000: hostname nor server name provided, or not known
> Error: Can't open display xenon:0.0

Open another xterm, from the X11 session of the plain user, and run:

    $ xhost +localhost

Then you'll be able to `connect' by running as root:

    xenon# setenv DISPLAY localhost:0

> I seem to remember never being able to su in xterm and be able
> to run any programs no matter what combination of settings I
> have used.

That may be true, depending on the version of X11 that you are
running, the current operating system and the setup of the X11
sessions.  I can't tell what you had done, since I wasn't there...

> I also think that the error messages might have been different
> but I am starting to lose track of the error messages for
> combinations of settings for hostname, DISPLAY, etc.  I
> probably need to start putting all of this down on paper so I
> can find any patterns.

Sure.  Keeping notes is always a good idea :)

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