Gnuplot 5.0 'set output filename' in a gnuplot script does not work

Question

I am newbie to Gnuplot, and starting with gnuplot 5.0.0. Here is my problem: Consider very simple example of a gnuplot script named save.gpl:

set terminal dumb  
plot sin(x) with linespoints pointtype 5, cos(x) w boxes lt 4  
set term png   
set output “graph.png”   
replot  
set term dumb

When I try run this script from the shell terminal my mac (OX 10.0):
$ gnuplot save.gpl
it throw a error in line 4 (set output “graph.png”) saying:

"save.gpl", line 4: internal error : STRING operator applied to non-STRING type.

Same thing happens when I try to load my script from the gnuplot: gnuplot > load save.gpl

But if I execute each command in my script one at a time in the "gunplot >" mode, everything goes fine.

However, I need to use set output “filename.png" statements in a lot bigger script several times to save several plots. So, have to use this statement in the script.

Thanks in advance.

Answer 1

You are using the wrong quotes. In your script you have the LEFT DOUBLE QUOTATION MARK (U+201C) and the RIGHT DOUBLE QUOTATION MARK (U+201D), which is wrong.

You must single ' (ASCII 0x27) or double quotes " (ASCII 0x22) as string delimiters, like you do in any scripting language.

set terminal pngcairo
set output "graph.png"
plot sin(x)