The first thing you need is a datafile, lets call ours 'a1':
remus> more a1
1 1
2 4
3 9
4 16
5 2
Now run gnuplot
remus> gnuplot
G N U P L O T
unix version 3.5
patchlevel 3.50.1.17, 27 Aug 93
last modified Fri Aug 27 05:21:33 GMT 1993
Copyright(C) 1986 - 1993 Colin Kelley, Thomas Williams
Send comments and requests for help to info-gnuplot@dartmouth.edu
Send bugs, suggestions and mods to bug-gnuplot@dartmouth.edu
Terminal type set to 'x11'
To see the graph issue the command:
gnuplot> plot 'a1'
Once the graph is as you want it to be issue the following commands to print it.
gnuplot> set terminal postscript landscape
Terminal type set to 'postscript'
Options are 'landscape monochrome dashed "Helvetica" 14'
gnuplot> set out "a1.ps"
gnuplot> plot 'a1'
gnuplot> quit
Make sure you have a postscript file:
remus> head a1.ps
%!PS-Adobe-2.0
%%Creator: gnuplot
%%DocumentFonts: Helvetica
%%BoundingBox: 50 50 554 770
%%Pages: (atend)
%%EndComments
/gnudict 40 dict def
gnudict begin
/Color false def
/Solid false def
remus>
You can now use the lpr command to print the file a1.ps.
remus> lpr -Pprintername a1.ps