I have one linux box (box1) which provides the X server.
On another linux box (box2), I have my perl scripts to debug.
On box1, I can do "ssh -X box2" and the DISPLAY variable is set to "localhost:10.0" and if I run my perl script manually (perl -d:ptkdb dbs.pl), the ptkdb window comes up on box1. I can click RUN and all goes well.
The perl code for dbs.pl is

#!/usr/bin/perl
print "Hello World\n";
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Now, when I want to run a CGI program, things don't go so well: The code is just as simple for dbs.cgi:

#!/usr/bin/perl -d:ptkdb
use CGI (':standard');
print header;
print start_html;
print "Hello";
print end_html;
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The problem now is that I get the message:

couldn't connect to display ":0" at
 /perl_modules/lib/site_perl/5.12.0/s390x-linux/Tk/MainWindow.pm
 line 55.
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Doing ssh -X sets the DISPLAY variable for me, but the web server does not know what to do. I tried adding a line like

$ENV{DISPLAY} = "localhost:0.0";
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But that didn't work. I have also used xhost to try and set things up, but to no avail. If I don't invoke with -d:ptkdb, then the cgi script properly displays "Hello" on the browser screen.
So, what other steps might I try, so that my cgi scripts can connect to the X server display? I guess the problem is that apache doesn't know how to redirect the X11 output to the host running my browser.