#!/usr/local/bin/perl
#Filename: sin.pl

# These path names must be adjusted for your system
$GNUPLOT = '/usr/bin/gnuplot';
$CONVERT = '/usr/local/bin/convert -transparency white ppm:- gif:-';

$|=1;  # to prevent buffering problems
print "Content-type: image/gif\n\n";  # required header

open (GRAPH,"| $GNUPLOT | $CONVERT") || die;
print GRAPH <<END;
set term pbm color
set size 0.5,0.5
plot sin(x)
END

close GRAPH;