use strict;

open( my $fout, ">myplot.gpt" )
  or die( "Problem: $!" );

print( $fout <<'EOF' );
  reset

  set terminal png size 320,160 medium
  set output 'myplot.png'

  set title "Test Plot"
  set xrange [0:5]
  set yrange [0:100]
  plot [0:5] "-" using 1:2 title "Distance" with lines
    1.0   20
    2.0   40
    3.0   40
    4.0   80
  end
EOF

close( $fout );

my $result = `gnuplot myplot.gpt`;
print( $result ) if ( $result );