Hi Emiliano, As Bruce pointed out, gifeffit is sort of old. To be honest, I thought I was the only one who used it. But it should work as a simple "enhanced command-line interface", and I'm sure it can work (it works for me on linux). I'll bet the problem you're having is with ifeffit / pgplot. You say that plain ifeffit and horae both work... I'll assume that means "including plotting", and that Python is incorrectly using the pgplot library from the debian package instead of the one built for Ifeffit with PGPLOT_Install. Here's something to try: ~> ldd /usr/local/bin/ifeffit ~> ldd /usr/lib/python2.5/site-packages/Ifeffit/_ifeffit.so Neither of these files should point to a 'libpgplot.so' If they do, I'd recommend (temporarily if necessary) removing the PGPLOT package (or at least the libpgplot.so file) and rebuilding Ifeffit and the python wrapper. Hope that helps, and let me know how it goes. Cheers, --Matt