I am using gnuplot 5.9 patchlevel 3 and I wanted to use different lt thus I wanted to reproduce the following this tutorial from gnuplot 5.0 patchlevel 1.
In particular if I copy it and launch it both from term and as .eps I couldn't see dashed lines, here the output 
In particular I do not understand the following line:
You will only see dashed lines if your current terminal setting permits it
What does it mean? How I can 'force' gnuplot to print the different dashed lines in .eps, .png or via screen?
I found this guide but its refer to a 4.2.5 version of gnuplot, even if I use:
set termoption dashed
or
set terminal x11 dashed
I can't see the dashed lines...Those are the terminals I can use in gnuplot 5.0 patchlevel 3 from help term:
canvas cgm context corel dumb dxf eepic emf emtex epslatex fig hpgl latex mf mp pcl5 pop postscript pslatex pstex pstricks push qms svg tek40xx tek410x texdraw tgif tkcanvas tpic vttek x11 xlib xterm
I red also this answer but gnuplot 5.0 doesn't support pngcairo (???) as a test, in fact, I just try:
set term pngcairo dashed
And I receive the answer:
Terminal type set to 'unknown'
^
unknown or ambiguous terminal type; type just 'set terminal' for a list
Thus I tried to install pngciaro following this page using homebrew which I found not so useful unfortunately due to the fact that the question about gnuplot 5.0 does not have an answer and because I receive some warning that could be connected with the installation of the pngcairo.