Last week, with the help of perlmonks, I got the following code to work outputting an image to the browser (another cgi page references this code as the source of the image).
#!/usr/bin/perl -w

# test.pl for testing real-time graph capabilities
# November 9, 2004
use CGI qw( :standard );
use CGI::Carp 'fatalsToBrowser';    
my $q = new CGI;
my $station = $q->param('sta');
my $constituent = $q->param('const');
my $combined = "$station" . "$constituent";

my $img = `/usr/local/bin/gnuplot $station $constituent $combined`;
print $q->header("image/png"), $img;

[download]
Now I want to do the process differently to more easily adjust the gnuplot set commands based on user input. I've been trying variations of the following code, but I'm getting either strange characters printed to the browser or currently the error "The server encountered an internal error and was unable to complete your request. Error message: Premature end of script headers: test6.pl" 
#!/usr/bin/perl -w

# test6.pl for testing real-time graph capabilities
# November 17, 2004
use CGI qw( :standard );
use CGI::Carp 'fatalsToBrowser';    #will print error message to user
my $q = new CGI;
open $station => "| /usr/local/bin/gnuplot" or die "$!\n";
print $station <<"--";
set terminal png color
set output
set xdata time
set timefmt "%Y%m%d"
set key left top title "Legend" box
set grid xtics ytics
set yrange [700:]
set format x "%Y"
set xlabel "Year"
set ylabel "Sodium, water, filtered, milligrams per liter"
set title "05056670 Western Stump Lake Major Ions"
plot "05056670.txt" using 2:3 title "P00930 Sodium dissolved"
--
print $q->header("image/png"),$station;

[download]

Any suggestions as to what I am doing wrong?

Thanks

In reply to gnuplot output to browser by kryberg

Title:
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