trouble running program in terminal after using 'su -l username'

[Phil Schaffner]

On Wed, 2004-01-14 at 14:34, David Jackson wrote:
> > (gnome-terminal:31609): Gtk-WARNING **: cannot open display:
> >
> > By default in Fedora X server is set to "-nolisten tcp". You can change
> > that in /etc/X11/gdm/gdm.conf by setting DisallowTCP=true -> false.
> > After X restart and trying what you want to achieve you have to also set
> > "xhost +localhost". You can set that line for automatically be executed
> > in /etc/X11/xinit/xinitrc.
> 
> Is that like doing a export DISPLAY=localhost:0.0
> Could John use VNC?

The "DISPLAY" environment tells the current process what display to use
by default and in this case should not be necessary.  Not sure how VNC
would help here.

"xhost +localhost" when executed by the owner of the X session allows
other users on the local machine to access the display.  (OT, or at
least more than asked for: "xhost +hostname.domain" allows users from
hostname.domain, "xhost +" leaves it wide-open - not advisable.  The
user on hostname.domain would have to do export
DISPLAY=yourhost.yourdomain:0.0 to bring up a window on your display.)

In this instance, executing the "xhost +localhost" either before the
"su" or in another terminal owned by the user who started the X session
seems to be sufficient, but then I'm not running a graphical login. I'm
an old command-line guy and prefer to do "startx" from the console in
runlevel 3.  Perhaps the gdm.conf magic is necessary for runlevel 5.

Phil