gnuplot how to give column number to plot dynamically?

Question

I am automating a task to create small graphs using gnuplot. And I need to pass the column number from the datafile that is to be plotted

pfile=system(\"echo         


        

Answer 1

it seems that one has to do colnum=int(system("echo $colnum")) so that the variable colnum is interpreted as an integer and not a string