How to pass command line argument to gnuplot

Question

I want to use gnuplot to draw figure from data file  say foo data  Currently  I hardcoded the data file name in the command file  say foo plt  and run command gnuplot foo plg to plot data  However  I want to pass the data file name as a command argument  e g  running command gnuplot foo plg foo data  How to parse the command line arguments in gnuplot script file  Thanks

User · Answer

This question is well answered but I think I can find a niche to fill here regardless, if only to reduce the workload on somebody googling this like I did. The answer from vagoberto gave me what I needed to solve my version of this problem and so I'll share my solution here.

I developed a plot script in an up-to-date environment which allowed me to do:

#!/usr/bin/gnuplot -c 
set terminal png truecolor transparent crop
set output ARG1
set size 1, 0.2
rrLower = ARG2
rrUpper = ARG3
rrSD = ARG4
resultx = ARG5+0 # Type coercion required for data series
resulty = 0.02 # fixed
# etc.

This executes perfectly well from command-line in an environment with a recent gnuplot (5.0.3 in my case).

$ ./plotStuff.gp 'output.png' 2.3 6.7 4.3 7

When uploaded to my server and executed, it failed because the server version was 4.6.4 (current on Ubuntu 14.04 LTS). The below shim solved this problem without requiring any change to the original script.

#!/bin/bash
# GPlot v<4.6.6 doesn't support direct command line arguments.
#This script backfills the functionality transparently.
SCRIPT="plotStuff.gp"
ARG1=$1
ARG2=$2
ARG3=$3
ARG4=$4
ARG5=$5
ARG6=$6

gnuplot -e "ARG1='${ARG1}'; ARG2='${ARG2}'; ARG3='${ARG3}'; ARG4='${ARG4}'; ARG5='${ARG5}'; ARG6='${ARG6}'" $SCRIPT

The combination of these two scripts allows parameters to be passed from bash to gnuplot scripts without regard to the gnuplot version and in basically any *nix.

User · Answer

You could even do some shell magic  e g  like this      bin bash inputfile    1    you could even do some getopt magic here                                                                                         generate a gnuplotscript  strip off bash header gnuplotscript   mktemp  tmp gnuplot cmd   basename    0    XXXXXX gnuplot   firstline   grep -m 1 -n      usr bin gnuplot     0    firstline   firstline       remove everything after the colon sed -e  1   firstline d   lt     0    gt     gnuplotscript                                                                                         run gnuplot  usr bin gnuplot -e  inputfile     inputfile        gnuplotscript   status    if      status  -ne 0      then   echo  ERROR  gnuplot returned with exit status     fi                                                                                      cleanup and exit rm -f    gnuplotscript   exit   status      usr bin gnuplot plot inputfile using 1 4 with linespoints      or whatever you want   My implementation is a bit more complex  e g  replacing some magic tokens in the sed call  while I am already at it      but I simplified this example for better understanding  You could also make it even simpler     YMMV

User · Answer

You can also pass information in through the environment as is suggested here  The example by Ismail Amin is repeated here   In the shell   export name plot data file   In a Gnuplot script       usr bin gnuplot  name system  echo  name   set title name plot name using   16   8  20 with linespoints notitle pause -1

User · Answer

In the shell write  gnuplot -persist -e  plot filename1 dat filename2 dat    and consecutively the files you want  -persist is used to make the gnuplot screen stay as long as the user doesn t exit it manually

User · Answer

The answer of Jari Laamanen is the best solution  I want just explain how to use more than 1 input parameter with shell variables   output test1 png data foo data gnuplot -e  datafile    data    outputname    output    foo plg   and foo plg   set terminal png set outputname  f x    sin x  plot datafile   As you can see more parameters are passed with semi colons  like in bash scripts   but string variables NEED to be encapsuled with      gnuplot syntax  NOT Bash syntax

User · Answer

You can pass arguments to a gnuplot script since version 5 0  with the flag -c  These arguments are accessed through the variables ARG0 to ARG9  ARG0 being the script  and ARG1 to ARG9 string variables  The number of arguments is given by ARGC    For example  the following script   script gp       usr local bin gnuplot --persist  THIRD ARG3 print  script name             ARG0 print  first argument          ARG1 print  third argument          THIRD  print  number of arguments     ARGC    can be called as     gnuplot -c script gp one two three four five script name          script gp first argument       one third argument       three number of arguments  5   or within gnuplot as  gnuplot gt  call  script gp  one two three four five script name          script gp first argument       one third argument       three number of arguments  5     In gnuplot 4 6 6 and earlier  there exists a call mechanism with a different  now deprecated  syntax  The arguments are accessed through      0      9  For example  the same script above looks like      usr bin gnuplot --persist  THIRD   2  print  first argument            0  print  second argument           1  print  third argument          THIRD print  number of arguments            and it is called within gnuplot as  remember  version  lt 4 6 6   gnuplot gt  call  script4 gp  one two three four five first argument       one second argument      two third argument       three number of arguments  5   Notice there is no variable for the script name  so  0 is the first argument  and the variables are called within quotes  There is no way to use this directly from the command line  only through tricks as the one suggested by  con-fu-se

User · Answer

vagoberto s answer seems the best IMHO if you need positional arguments  and I have a small improvement to add   vagoberto s suggestion      usr local bin gnuplot --persist  THIRD ARG3 print  script name             ARG0 print  first argument          ARG1 print  third argument          THIRD  print  number of arguments     ARGC    which gets called by     gnuplot -c script gp one two three four five script name          script gp first argument       one third argument       three number of arguments  5   for those lazy typers like myself  one could make the script executable  chmod 755 script gp   then use the following      usr bin env gnuplot -c  THIRD ARG3 print  script name             ARG0 print  first argument          ARG1 print  third argument          THIRD print  number of arguments     ARGC   and execute it as       imb plot a b c d script name            imb plot first argument       a third argument       c number of arguments  4

User · Answer

Yet another way is this   You have a gnuplot script named scriptname gp      usr bin gnuplot -p   This code is in the file  scriptname gp  EPATH    0 FILENAME    1   plot FILENAME   Now you can call the gnuplot script scriptname gp by this convoluted peace of syntax   echo  call   scriptname gp              data dat       gnuplot

User · Answer

You may use trick in unix linux environment    in gnuplot program  plot   dev stdin      In command line  gnuplot program plot  lt  data dat

User · Answer

You can input variables via switch -e    gnuplot -e  filename  foo data   foo plg   In foo plg you can then use that variable    cat foo plg  plot filename pause -1   To make  foo plg  a bit more generic  use a conditional   if   exists  filename    filename  default dat  plot filename pause -1   Note that -e has to precede the filename otherwise the file runs before the -e statements  In particular  running a shebang gnuplot    usr bin env gnuplot with   foo plg -e     CLI arguments will ignore use the arguments provided

[command-line] How to pass command line argument to gnuplot?

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