Subject: plot2d in Lisp CGI (was: plot2d output "")
From: Rupert Swarbrick
Date: Tue, 18 Sep 2007 10:45:06 +0100
On Mon, 17 Sep 2007 13:17:21 -0700 (PDT)
Yigal Asnis <yigalasnis at yahoo.com> wrote:
> It turns out that return value of plot2d ("") wasn't
> problem. I suppressed it by (progn #$plot2d(...)$
> (princ "something I need to print")) but CGI program
> still stuck.
> If I execute the CGI file from terminal, it works -
> plot2d generates plot file and all other output work
> as expected.
> But if I point to CGI file with browser, the plot file
> isn't generated and all commands after plot2d aren't
> executed.
> I think the problem is calling external function
> (gnuplot) from CGI.
> I use Apache with mod_cgi on Debian.
>
> Yigal Asnis
Are you on *nix?
I don't know much at all about cgi programming in general or with
gnuplot in particular, but maybe there's a problem because gnuplot is
an X11 program?
In particular, try running some random X11 program (gnuplot,xeyes ?)
from a console (Ctrl-Alt-F1) on Linux and you'll get a 5 sec. or so
wait followed by an error message complaining that it was unable to
communicate with the X server (because the DISPLAY variable was not set
and it doesn't know who to ask).
Running from Apache as a CGI script, your program might have a similar
problem. Have you tried running your CGI script via a proper console? I
think that would show whether this is the problem.
(As to the solution, I have no idea!)
Rupert
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