gnuplot is a 24-year old program that is maintained via patches (the original copyright and license requires that - http://gnuplot.cvs.s...right?view=markup ).
A newer package that uses similar script syntax as gnuplot but is much more friendly to extension is pyxplot (and it includes pie charts) - http://pyxplot.org.u...bution/index.html [Thanks for giving me the incentive to look into this - pyxplot looks like a very nice package, though it uses LATeX and would have a learning curve for me.]
gnuplot fits with the way I work, but has a learning curve.
I see there's a CPAN module for doing gnuplot charts with perl, and a pie chart module for that - http://kobesearch.cp.../Gnuplot/Pie.html That seems like a nice package, but I haven't used it myself, and I can't find an example.
Another package that might fit your needs better than gnuplot is matplotlib for python. It does pie charts out of the box.
Since it does more out of the box, it's a bigger package with more dependencies, but prebuilt binaries are available. http://matplotlib.so...s/installing.html
Whether it's a good fit for you, I can't say. But it does plotting very very well.
HTH a little.