[Matplotlib-users] Saving a figure to StringIO or similar

I am writing a web server app that creates charts among

    > other things. I am trying to get rid of the temporary file
    > that I use to transmit the figures created with matplotlib
    > to the actual web server. Although print_figure says "If
    > filename is a fileobject, write png to file object (thus
    > you can, for example, write the png to stdout)" I can't
    > successfully write anything to stdout. Anyone knows an
    > example or can give me some hint what I can do to get rid
    > of the tempfile?
    >> Short answer: no known way to do this currently, though we'd
    >> like to figure it out. As far as I know (and could very well
    >> be wrong) libpng requires a FILE*, which StringIO and cStringIO
    >> do not provide.

    > StringIO isn't the issue here; being able to write to
    > sys.stdout, which ought to have a valid FILE* underneath,
    > is the issue.

Thanks for reminding me about this. I thought it was possible to do
this, but had managed to forget

    import sys
    from pylab import plot, savefig, show

which I run with

  > python test.py -dAgg > test.png

produces the expected figure.