Question about "export DISPLAY"

[Christopher Browne]

On 5/4/06, bassix-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org <bassix-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> Hi,
>
> I'm trying to install IBM DB2 (I got the CD at LinuxWorld), and I'm
> stuck on the following:
>
> "You must have X/Windows software capable of rendering a graphical
> user interface for First Steps to run on your computer. Ensure that
> you have properly exported your display. For example, export
> DISPLAY=9.26.163.144:0"
>
> # export DISPLAY=127.0.0.1:0
>
> # ./db2exc_LNX_26x86/db2setup
>
> DBI1190I db2setup is preparing the DB2 Setup wizard which will
>           guide you through the program setup process. Please
>           wait.
>
> The DISPLAY variable is not set properly.  Ensure that the DISPLAY
> variable is set properly and that permissions are set properly to open
> windows on the display specified, then rerun the command.
>
> ...Is 127.0.0.1:0 correct for me to use? I obviously want it to use
> the same machine. Is there some other things I need to do?
>
> Thanks for any help... I am not familiar with the export DISPLAY command... :-)
>
> -Steve.

Well, if you're running X, you will already have DISPLAY set to something.

For instance, on my laptop, where I'm typing this, I see the following:

cbbrowne at mobile:~/slony1-engine> echo $DISPLAY                        
                                                                      
         Thursday 23:13:29
:0

That value, :0, would be quite suitable.

If I changed it to something else, things would probably not turn out so well.

The case where you might have to "get fiddly" about it is if you log
in as yourself, and then need to have a session running as root have
access to that display.  Mumble, mumble, xauth, mumble, "AAAHHHH!!!!",
thud...

If the installation needs to run as root, it's best if you can run an
X session _as root_ so no fighting with MIT Magic Cookies or xauth or
xhost need get in the way...
--
http://www3.sympatico.ca/cbbrowne/linux.html
Oddly enough, this is completely standard behaviour for shells. This
is a roundabout way of saying `don't use combined chains of `&&'s and
`||'s unless you think Gödel's theorem is for sissies'.
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