Re: using gnuplot as a filter

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Pádraig Brady wrote:

> I want to read data on stdin and write png to stdout.

You're missing the fact that you also want to read input to gnuplot from 
a second place: the script file.  It's this script file that gets in the 
way of what you're trying to do, as shown by the fact that

	(cat script ; gen_data) | gnuplot

works.  As does

	gnuplot script <(gen_data)

gnuplot is designed to take commands, not data, from its standard input. 
  It's an extension for it to accept data from the command input stream.

> I.E. behave like a standard unix filter which has lots of advantages.

Standard unix filters aren't in the habit of taking commands from their 
standard input.  gnuplot is.