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[GEMPAK #FYS-891494]: odd problem with gdcross

> Hi Steve,
> 
> I'm having a problem running a GEMPAK script under a cron job.
> Everything seems to run ok, but at the end I'm getting this error:
> 
> [GEMPLT -83]  NDISP - DISPLAY not set or invalid
> 
> I've set the DEVICE parameter to "gf", so I don't quite understand
> why DISPLAY needs to be set.  Granted, cron runs with minimal
> environment variable settings, so it's not surprising that nothing's
> set for DISPLAY.  I've tried setting DISPLAY to :0.0 within the
> script, but GEMPAK doesn't seem to like that, either.  Is there
> something I can set DISPLAY to in order to get it to create the
> gif files?
> 
> Thanks for any help you can provide,
> 
> 
> Brian
> 
> 
> 


Brian,

There are 2 different GIF output drivers:

GF uses the X display to render the image, generally has better looking fonts 
since it is using the X fonts.

GIF does not use the X display, uses software fonts.

When you run a cron, you typically don't have access to the console display, 
even if you set the DISPLAY variable
since the console user has a magick cookie, and unless you allow other access 
(using xhost + localhost),
the cron's won't be able to connect to the display. Moreover, if you log off 
the console, there is no access.
You can use the GIF driver, or, set up a virtual X server (using the Xvfb 
program) which creates a display in 
memory that crons can draw to, typically using DISPLAY :1, such as:
Xvfb :1 -screen 0 1600x1200x24 &

See the Xvfb man page for further information.

Steve Chiswell
Unidata User Support

Ticket Details
===================
Ticket ID: FYS-891494
Department: Support GEMPAK
Priority: Normal
Status: Closed