I have 6 files which need to be plotted as line graphs with error margins and output them to different png files. The file format is as follows.

seconds mean-average min max

How would I go about plotting these graphs automatically? So I run a file called bash.sh and it will get the 6 files and output the graphs to different .png files. Titles and axis labels are also required.

3 Answers 3


If I understand correctly, this is what you want:

for FILE in *; do
    gnuplot <<- EOF
        set xlabel "Label"
        set ylabel "Label2"
        set title "Graph title"   
        set term png
        set output "${FILE}.png"
        plot "${FILE}" using 1:2:3:4 with errorbars

This assumes your files are all in the current directory. The above is a bash script that will generate your graphs. Personally, I usually write a gnuplot command file (call it, say, gnuplot_in), using a script of some form, with the above commands for each file and plot it using gnuplot < gnuplot_in.

To give you an example, in python:

#!/usr/bin/env python3
import glob
commands=open("gnuplot_in", 'w')
print("""set xlabel "Label"
set ylabel "Label2"
set term png""", file=commands)

for datafile in glob.iglob("Your_file_glob_pattern"):
    # Here, you can tweak the output png file name.
    print('set output "{output}.png"'.format( output=datafile ), file=commands )
    print('plot "{file_name}" using 1:2:3:4 with errorbars title "Graph title"'.format( file_name = datafile ), file=commands)


where Your_file_glob_pattern is something that describes the naming of your datafiles, be it * or *dat. Instead of the glob module, you can use os as well of course. Whatever generates a list of file names, really.

  • 1
    Your comment in your answer is a cleaner solution, why not expand the answer to show an example. +1
    – bsd
    Mar 18, 2012 at 13:32
  • Thanks for the comment. I was just doing that as you commented on the post.
    – Wojtek
    Mar 18, 2012 at 13:45

Bash solution, using a temporary command file:

echo > gnuplot.in 
for FILE in *; do
    echo "set xlabel \"Label\"" >> gnuplot.in
    echo "set ylabel \"Label2\"" >> gnuplot.in
    echo "set term png" >> gnuplot.in
    echo "set output \"${FILE}.png\" >> gnuplot.in
    echo "plot \"${FILE}\" using 1:2:3:4 with errorbars title \"Graph title\"" >> gnuplot.in
gnuplot gnuplot.in

This might help.

#set terminal postfile       (These commented lines would be used to )
#set output  "d1_plot.ps"    (generate a postscript file.            )
set title "Energy vs. Time for Sample Data"
set xlabel "Time"
set ylabel "Energy"
plot "d1.dat" with lines
pause -1 "Hit any key to continue"

Execute the script file as gnuplot filename.

Click here for more details.

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