If you feed gnuplot its commands from the unix command line, you can also pipe data to it from another program, like
zcat which reads in a gzipped file and prints it out, e.g.:
zcat datafile.gz | gnuplot -p -e 'plot "-" u 1:2'
Apparently, in place of a filename, you can give gnuplot's
plot command a shell command to run and use the output of. Just put a
< in front:
plot "< zcat datafile.gz" u 1:2
You should be able to use that multiple times to do what you want.
(Answer courtesy of
philipp.janert on the 'Gnuplot in Action' forum http://www.manning-sandbox.com/message.jspa?messageID=77092)