GNUPlot: Terminal set unknown

Question

    G N U P L O T
    Version 4.6 patchlevel 4    last modified 2013-10-02 
    Build System: Linux x86_64

    Copyright (C) 1986-1993, 1998, 2004, 2007-2013
    Thomas Williams, Colin Kelley and many others

    gnuplot home:     http://www.gnuplot.info
    faq, bugs, etc:   type "help FAQ"
    immediate help:   type "help"  (plot window: hit 'h')
    Terminal type set to 'unknown'
    gnuplot>

Hi, gnuplot displays me Terminal type set to 'unknown'.
And if I enter the following command.

gnuplot> plot "./MergePlot.dat" with linespoint

Nothing happens.

Did you install gnuplot or gnuplot-x11 (or something else)? — steeldriver, Dec 18 '15 at 12:45
Which is installed now? AFAIK Terminal type set to 'unknown' is normal for gnuplot-nox (which is what gets installed by default if you just specify gnuplot). Last time I checked, the default for gnuplot-x11 should be wxt. — steeldriver, Dec 18 '15 at 14:32

score 3 · Answer 1 · edited Jun 12 '20 at 14:37

Setting the correct terminal

The error you find means that gnuplot is not recognizing a valid terminal. You have to set a valid one. To know the list of the available ones you can ask from the command line of gnuplot

gnuplot> set terminal

And it will answer with something like

Available terminal types:
       cairolatex  LaTeX picture environment using graphicx package 
                   and Cairo backend
           canvas  HTML Canvas object
              cgm  Computer Graphics Metafile
          context  ConTeXt with MetaFun (for PDF documents)
            corel  EPS format for CorelDRAW
             dumb  ascii art for anything that prints text
          ...  Many linees  ...

          gif  GIF images using libgd and TrueType fonts
         gpic  GPIC -- Produce graphs in groff using the 

          ...  Other linees  ...

For each of them you can ask to gnuplot itself for more information, for example with help terminal gif.

Then you can simply set the terminal, if you have try the dumb one it's lovely.

gnuplot> set terminal dumb
gnuplot> plot 0.5*sin(x/2)  lt 0, cos(x/2)
1 ++---------------+---------------####---------------+---------------++
  +                +             ##  + ##          0.5*sin(x/2) +....+ +

0.8 ++                            #        #             cos(x/2) ######++
      |                            #          #                            |
  0.6 ++                          #            #                          ++
      |++++++                    #              #+++++++                   |
  0.4 ++    +++                 #             ++ #     +++                ++
      #       +++               #           ++   #        ++               #
  0.2 +#        ++            ##          ++      ##        +             #+
    0 +#          ++          #          ++        #         ++           #+
      | #          ++        #         ++           #         ++         # |
 -0.2 ++ #           +      #         ++             #          ++      # ++
      |  ##           ++    #       ++               #           +++   ##  |
 -0.4 ++   #            +++#      ++                  #            +++#   ++
      |     #             #+++++++                     #             #+++++|
 -0.6 ++    #             #                            #             #    ++
      |      ##         ##                              ##         ##      |
 -0.8 ++      #        #                                  #        #      ++
      +        ##    ###                 +                ###    ##        +
   -1 ++---------#####-+-----------------+----------------+-#####---------++
     -10              -5                 0                5                10

If you have not the possibility to use a terminal from which "you can see" (wxt,qt,x11,aqua...), use a graphic format and save the output on an external file. In this way you will create a file in the directory from which you run gnuplot.

set terminal png enhanced truecolor    # ... whatever ...
  set output 'tempfile.png'            # you need to redirect to a file the output 
    plot 0.5*sin(x/2)  lt 0, cos(x/2)  # your plot commands     
    # replot # it should be cosy if you are not doing multiplot 
  set out                              # restore the output redirection
set terminal GNUTERM                   # restore the default terminal

Note:
You may need to install the different packages -qt,-nox,-x11 to have different features (the OP just did it) or to compile by yourself to add other ones.

Gamecompiler · Answer 2 · 2015-12-29T20:25:41.483

You definitely missunderstood how to use gnuplot.
You did not tell gnuplot what it has to plot.

And what the output should look like.

Please read the manual. Otherwise nobody will help you if you did not read the manual. http://people.duke.edu/~hpgavin/gnuplot.html

Otherwise, here is a example how a working plot would look like as commands.

#SET TERMINAL
set term svg
set output 'temp-verlauf.svg'
set title "Temperaturverlauf"

#Axes label
set xlabel "Messzeitpunkt"
set ylabel "Luftfeuchte/Temperatur"
set y2label "Luftdruck"

#Axis setup
set xdata time # x-Achse wird im Datums/Zeitformat skaliert
set timefmt "%d.%m.%Y\t%H:%M:%S" # Format Zeitangaben yyyy.mm.dd_hh:mm:ss
set format x "%H:%M" # Format für die Achsenbeschriftung


#Axis ranges
set yrange [0:60] # die y-Achse geht von:bis

#Tics
set ytics nomirror
set y2tics nomirror

#OTHER
set datafile separator "\t"
set xrange ["06.11.2014 14:00:00":"07.11.2014   21:00:00"]

plot \
"file.dat" every 10 using 1:5 title "Luftfeuchte" with lines, \
"file.dat" every 10 using 1:6 title "Temperatur" with lines, \
"file.dat" every 10 using 1:7 title "Luftdruck" with lines axes x1y2, \
"file.dat" every 10 using 1:17 title "Niederschlagsintensitaet Synop (4677)" with lines

Stranger things have happened. :D – muru Dec 29 '15 at 20:29 — muru, Dec 29 '15 at 20:29

score 0 · Answer 3 · answered Jul 19 '22 at 06:57

I guess you don't have the repositories and latest packages in your system, thats why the problem arise. Therefore, run this command in your terminal,

sudo apt-get install gnuplot-x11
or
sudo apt-get install gnuplot-qt

That's should fix your issue.(see enter link description here)

GNUPlot: Terminal set unknown

3 Answers3

Setting the correct terminal