set grid nopolar
set size 0.8,0.6
set grid xtics nomxtics ytics nomytics noztics nomztics \
 nox2tics nomx2tics noy2tics nomy2tics nocbtics nomcbtics
set grid layerdefault   linetype 0 linewidth 1.000,  linetype 0 linewidth 1.000
unset logscale
set autoscale y
set xlabel "Time(sec)" font "Arial,12"
set ylabel "verlust in %" font "Arial, 12" 
set ytics    ( 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0)
set title "Packet Loss" font "Arial,12" 
set yrange [ 0.000 : 4.000 ] #noreverse nowriteback	

plot 'plot.dat' with impulses lt 3 lw 2 ti "Packet Loss"
set terminal png
set output "| cat -"
#set output "Packetloss2.png"
#set terminal png
#replot