How to call gnuplot from CLI and save the output graph to the image file?

Question

I'm writing a batch file which will also generate a gnuplot graph from a dat file.

I wish to call gnuplot from the command line, using the gnuplot "gnu" script I have written, and save the output graph to an image.

Something like:

gnuplot.exe script.gnu > image.png

Any ideas?

Answer 1

You don't have to redirect the output from gnuplot into an image file; you can set that inside the gnuplot script itself:

set terminal png
set output 'image.png'

If you want to have a variable output name, one simple way to do that in bash is to wrap the gnuplot commands thus:

#!/bin/bash

echo "set terminal png
set output '$1'
plot 'data.dat'" | gnuplot

This way you can run the bash script with an argument for the output file name:

./plotscript.sh image.png

Answer 2

Simply putting the following line will make gnuplot to return png-format bytecode. Thus, you can redirect the output to a png-file.

set terminal png