topic Re: Error Message - DDopen: No usable visual class in Operating System - HP-UX

Error Message - DDopen: No usable visual class

Andrew Kaplan — Fri, 21 Sep 2007 15:57:33 GMT

Hi there --

I am trying to run remotely an X application that resides on an HP-UX 10.20 system on a Fedora Core 2 workstation. The script that I am running runs a tcsh shell and executes the setenv DISPLAY command to the workstations ip address. The executable is a perl script. When I try to run the application, I get the following error message:

DDopen: No usable visual class

Can someone tell me what that means, and how can I correct it? Thanks.

Re: Error Message - DDopen: No usable visual class

Steven Schweda — Fri, 21 Sep 2007 16:25:07 GMT

To what, exactly, is DISPLAY being set?

> [...] setenv DISPLAY command to the
> workstations ip address.

An IP address (alone) is not an appropriate
value. The general form is:

hostname:displaynumber.screennumber

"man X" may supply the details.

Re: Error Message - DDopen: No usable visual class

Andrew Kaplan — Tue, 25 Sep 2007 13:15:26 GMT

Hi there --

I checked to see what the setenv DISPLAY synatx was, and it is :0.0

Any other ideas? Thanks.

Re: Error Message - DDopen: No usable visual class

Steven Schweda — Tue, 25 Sep 2007 14:03:47 GMT

Knowing nothing about "the application", I
don't know which visual classes it will find
usable. "xdpyinfo" should tell you which
visual classes the X server offers.

Re: Error Message - DDopen: No usable visual class

Andrew Kaplan — Tue, 25 Sep 2007 14:44:02 GMT

Hi there --

I ran the xpdyinfo command on several machines: two where the application worked, and two where it did not work. I outputted the results to several files.

I then ran the diff command to see if there were any noticeable differences. The results were the following: The workstations where the application did not work showed a difference in the name of the display line from that on one where the application did work. However, even on one of the workstations where the application worked, there was also a difference in the name of the display line.

Re: Error Message - DDopen: No usable visual class

Steven Schweda — Tue, 25 Sep 2007 15:20:00 GMT

If "the application" (whatever it is) works
from some Linux workstations but not from
others, then I'd look for the problem on the
Linux workstations, not on the HP-UX system.

When you ran your tests:

Were you logged in as the same user each
time?

Were you connected to the HP-UX system in the
same way as when "the application" is run?
(I don't know about your Linux systems, but
on HP-UX (11i v1), SSH with X forwarding can
affect the apparent properties of the X
server.)

> The script that I am running [...]

Does anything change if you de-automate
things, and do more stuff manually?

Obviously, something is different between the
workstations where the thing works and those
where it doesn't. Or am I delusional
(again)?

Re: Error Message - DDopen: No usable visual class

Andrew Kaplan — Tue, 25 Sep 2007 15:36:11 GMT

Hi there --

Here are the answers to your questions:

>When you ran your tests:
>Were you logged in as the same user each
>time?

>>Yes, I was logged in as the same user >>each time.

>Were you connected to the HP-UX system in >the same way as when "the application" is >run?

>>I was connected the same way as when the >>application was run.

>Does anything change if you de-automate
>things, and do more stuff manually?

>>The error messages that appear onscreen >>indicate missing Vector fonts.