plot_time

set terminal pngcairo size 1200,600 enhanced font 'Verdana'
set output sprintf('%s.png', filename)
set timefmt '%d/%m/%Y %H:%M:%S'
set xdata time
set format x '%H:%M:%S'
set grid ytics lc rgb "#bbbbbb" lw 2 lt 1
set yr [1000:4500]
set title "Processzor terhelés"
set xlabel "Time (Hour:Minute:Second) "
set ylabel "MHz "
plot "t_log.txt" using 5:2 with lines title "core:1" linewidth 3,\
     "t_log.txt" using 5:3 with lines title "core:2" linewidth 3,\
     "t_log.txt" using 5:4 with lines title "core:3" linewidth 3,\
     "t_log.txt" using 5:5 with lines title "core:4" linewidth 1
replot