gnuplot example

sensors.plot

# Remove quotes from the input file if needed:
#   $ sed -i "s/'//g" 20170623.csv

# How to use this script:
#   $ gnuplot -e "filename='20170623.csv'" sensors.plot

set terminal pngcairo size 640,480 enhanced font 'Verdana,10'
set output system('basename '.filename.' .csv').'.png'

set multiplot layout 2,1 rowsfirst title filename font ",14"

set datafile separator ','
set xdata time
set timefmt '%H:%M'
set format x "%H:%M"
#set xlabel "time (%H:%M)"
set xtics rotate
set grid
set key outside

set y2tics
set ylabel "temperature (°C)"
set y2label "humidity (%)"
set rmargin at screen 403.0/640
set bmargin at screen 230.0/480
plot filename using 1:3 with lines title 'temperature' axes x1y1, '' using 0:4 with lines title 'humidity' axes x2y2

set lmargin at screen 75.0/640
set tmargin at screen 180.0/480
unset bmargin
unset ylabel
set format x ""
set xlabel ""
set y2label "pressure (mbar)"
plot filename using 0:2 with lines title 'pressure' axes x2y2 ls 3

unset multiplot