Re: X display not working anymore (193 Views)
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Regular Advisor
Danesh Qureshi
Posts: 173
Registered: ‎11-07-2005
Message 1 of 16 (193 Views)

X display not working anymore

I have a server running TRU64 Unix V5.1B. From my Laptop computer I am logged into the server using ssh (secure shell). I have set the X11 tunnelling with my ssh session.

When I type xclock at the shell prompt there no xclock display
In fact any X application does not display on my screen. I have Exceed server running on my laptop from I login via ssh to my TRU64 Unix server.

All X applications use to work 7 months ago but recently they do not display anything.

Any help would appreciated.
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Honored Contributor
Steven Schweda
Posts: 9,084
Registered: ‎02-23-2005
Message 2 of 16 (193 Views)

Re: X display not working anymore

> All X applications use to work [...]

Perhaps something has changed.

"echo $DISPLAY"?
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Regular Advisor
Danesh Qureshi
Posts: 173
Registered: ‎11-07-2005
Message 3 of 16 (193 Views)

Re: X display not working anymore

This is what $DISPLAY reports within my ssh session

lysithea$ echo $DISPLAY
lysithea.mdx.ac.uk:0.0
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Honored Contributor
Steven Schweda
Posts: 9,084
Registered: ‎02-23-2005
Message 4 of 16 (193 Views)

Re: X display not working anymore

> This is what $DISPLAY reports within my
> ssh session

Great. Now if I knew the names of any of the
computers involved here, ...

Or were you hoping for help from some psychic
who already knows everything about your
environment?
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Honored Contributor
Vladimir Fabecic
Posts: 1,128
Registered: ‎03-03-2005
Message 5 of 16 (193 Views)

Re: X display not working anymore

Did something get changed with ssh server settings?
Is there a firewall between laptop and TRU64 server?
Please send more details.
In vino veritas, in VMS cluster
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Honored Contributor
Pieter 't Hart
Posts: 1,984
Registered: ‎09-04-2002
Message 6 of 16 (193 Views)

Re: X display not working anymore

>This is what $DISPLAY reports within my >ssh session
>
>lysithea$ echo $DISPLAY
>lysithea.mdx.ac.uk:0.0

So when logged in into lysithea, your $DISPLAY pointt to lysithea as outputdevice.
On the lysithea console the clock may appear and not on your laptop!
=> correct setting $DISPLAY in $HOME/.profile or $HOME/.dtprofile
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Regular Advisor
Danesh Qureshi
Posts: 173
Registered: ‎11-07-2005
Message 7 of 16 (193 Views)

Re: X display not working anymore

Sorry guys I understand you need more information about my environment in order to help me.

So on the main Lysithea console the xclock appears fine but not on my laptop.

There is a firewall between my laptop and Lysithea and I can login to Lysithea with ssh after authenticating to the firewall. We have 3 other servers running the same version of the Tru64 Unix 5.1b and all 3 servers are behind the firewall and xclock appears on my laptop for each of the 3 systems using ssh.

I have not changed any settings on ssh apart from enabelling X tunnelling in ssh for Lysithea.

I have noticed if I type xclock & on my laptop the xclock application seems to be "killed" immediately without any errors.

There are no xclock processes after I type xclock & running in the backgroundd.

I have tried using Exceed and Xming on my laptop as the X server but xclock still does not appear on my laptop. The last time xclock worked on my laptop was 8 or 9 months ago. We need to install Oracle which uses a GUI but we cannot proceed as it uses X server for the installation from a laptop.

I've looked at the sshd settings all looks fine to me.

I understand its a difficult to help me without giving you full details of the current environment.

I dont know where else to look.
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Honored Contributor
Steven Schweda
Posts: 9,084
Registered: ‎02-23-2005
Message 8 of 16 (193 Views)

Re: X display not working anymore

> lysithea$ echo $DISPLAY
> lysithea.mdx.ac.uk:0.0

> I have set the X11 tunnelling with my ssh
> session.

Apparently you haven't. Or perhaps your
shell start-up script ("~/.profile"?) sets
DISPLAY to this value after the SSH stuff
sets it to what it should be.
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Honored Contributor
Pieter 't Hart
Posts: 1,984
Registered: ‎09-04-2002
Message 9 of 16 (193 Views)

Re: X display not working anymore

try if "$HOME/.dt/errorlog" provides any clueues.

Pieter
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Honored Contributor
Pieter 't Hart
Posts: 1,984
Registered: ‎09-04-2002
Message 10 of 16 (193 Views)

Re: X display not working anymore

Also try to enable logging within the Xserver on your laptop, it may not accept the tunnel.

also try setting $DISPLAY to "hostname:0.1" instead of ":0.0"
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Honored Contributor
Vladimir Fabecic
Posts: 1,128
Registered: ‎03-03-2005
Message 11 of 16 (193 Views)

Re: X display not working anymore

What happens when you do:
# xclock (not "xclock &")
Is there an error message?
In vino veritas, in VMS cluster
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Honored Contributor
Steven Schweda
Posts: 9,084
Registered: ‎02-23-2005
Message 12 of 16 (193 Views)

Re: X display not working anymore

> What happens when you do:

If DISPLAY points to the wrong
host:server.screen, who cares what the error
message might be?
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Honored Contributor
Vladimir Fabecic
Posts: 1,128
Registered: ‎03-03-2005
Message 13 of 16 (193 Views)

Re: X display not working anymore

And what if DISPLAY does not point to the wrong host:server.screen?
Anyway, it can also be a permission problem (OK, I do not think so, but ...) or env problem (PATH).
Error message may help.
In vino veritas, in VMS cluster
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Regular Advisor
Danesh Qureshi
Posts: 173
Registered: ‎11-07-2005
Message 14 of 16 (193 Views)

Re: X display not working anymore

I tried to change the DISPLAY to 0.1 but I still cannot get any X application to work.

If I type xclock only, nothing happens. I get returned to the shell prompt straight away without any error message. It is very odd there is no error message after I type xclock. If I run "xclock &" I did not see any xclock process when I use "ps -eaf | grep -i xclock" to check for it. Normally, you would see background process of xclock.

See output below of xclock command.

lysithea$ xclock
lysithea$
lysithea$ xclock &
[1] 16470
lysithea$
[1] + Done xclock &
lysithea$


As I mentioned if I run xclock from the main Tru64 Unix console I see it appear on the screen.

I will reboot the server which been running for 448 days. May be rebooting may fix it.

The server was fully patched to patch kit 6 almost two years ago.
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Honored Contributor
Steven Schweda
Posts: 9,084
Registered: ‎02-23-2005
Message 15 of 16 (193 Views)

Re: X display not working anymore

> And what if DISPLAY does not point to the
> wrong host:server.screen?

Good point. Perhaps black really is white,
and up really is down. But I doubt it.

The info from the questioner is vague and
incomplete, but, as I understand / assume /
conjecture what's happening here, lysithea =
lysithea.mdx.ac.uk, and that's the Tru64
system, not the laptop with the X server.
So, I conclude that any DISPLAY which uses
lysithea:0 for its host:server part must be
wrong.

I don't have a laptop running Exceed, but I
do have a Sun Solaris workstation, and when
I use "ssh -X" to connect from it to another
system, I get results like the following.

To a Tru64 system:

sol> ssh -X urtx
[...]
HP Tru64 UNIX V5.1B (Rev. 2650); Mon Feb 19 11:57:07 CST 2007
No mail.
urtx> echo $DISPLAY
urtx.antinode.info:10.0

To an HP-UX (11.11) system:

sol> ssh -X dy
[...]
Value of TERM has been set to "xterm".
dy $ echo $DISPLAY
10.0.0.39:10.0

where 10.0.0.39 is the IP address of "dy",
the HP-UX system.

So, I conclude that a typical sshd sets up
a virtual X server at server_host:10.0 (and
it even seems to work around here).

The questioner reported that his DISPLAY was
"lysithea.mdx.ac.uk:0.0". To me, this does
not appear to be consistent with his claim
that he had "set the X11 tunnelling with
[his] ssh session". Based on the results of
my tests, I'd expect it to be something like
"lysithea.mdx.ac.uk:10.0".

I've tried to guess who set DISPLAY to the
reported value, but so far I've learned
nothing about it. My guess is still that
it's something in the user's shell start-up
script(s), but my psychic powers are too weak
to tell me more.

I have code in my own "~/.profile" which
looks at the output of "who am i", and uses
it to set DISPLAY, but it's inside a test
like this:

if [ -z "$DISPLAY" ]; then
[...]
fi

so, if someone else (like, say, sshd) sets
DISPLAY for me, I don't whack its (good)
DISPLAY definition with my (bad) DISPLAY
definition.


> May be rebooting may fix it.

The X Window System is not Microsoft Windows,
so I doubt it.
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Regular Advisor
Danesh Qureshi
Posts: 173
Registered: ‎11-07-2005
Message 16 of 16 (193 Views)

Re: X display not working anymore

The xclock problem has been solved.

The xclock file in the /usr/bin/X11 directory was empty i.e. zero blocks and the creation date of the xclock file was 31st Jan 2008.

I dont know how xclock file got to be in
this state.

I've copied xclock file from another Tru64 unix system to this one.

Now xclock appears on my laptop fine.

Thank you to everyone for their help.
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